Smithian ammonoid faunas from Utah: implications for Early Triassic biostratigraphy, correlation and basinal paleogeography

Abstract

Intensive sampling of the lower portion of the Thaynes and Moenkopi Groups (Lower Triassic) at separate localities within the Confusion Range, Pahvant Range, Mineral Mountains, Star Range, Kanarraville, Cedar City, Torrey and San Rafael Swell areas (mainly central and southern Utah, USA) leads to the recognition of a new key regional Smithian ammonoid succession. The new biostratigraphical sequence, which is more precise than the long-recognized Meekoceras gracilitatis and Anasibirites kingianus Zones, comprises twelve subdivisions, thus resulting in a sequence with much higher resolution that can be correlated not only with other western USA sites, but also with major worldwide localities as well. Middle and late Smithian faunas contain many taxa with wide geographic distribution, thus enabling long-distance correlation with faunal successions from other regions (e.g., British Columbia, Canadian Arctic, South China, Spiti and Oman). New assemblages from the lowermost beds are the least diversified and poorest preserved; they represent the earliest early/middle Smithian ammonoid faunas reported from the western North American basin. They highlight (a) the sudden Smithian advancement of the marine transgression within this epicontinental sea, (b) that this event is diachronous, and (c) that the paleotopography of the basin most likely was highly irregular. The newly obtained ammonoid succession also allows us to date and follow the transgression from the northern and central part of the basin to the southwesternmost and southeasternmost parts, which were reached during the late Smithian (Anasibirites kingianus beds). In addition, we briefly discuss the now-limited previous regional biozonation in the light of these new results. One new genus (Minersvillites) and nine new species (Kashmirites utahensis, Kashmirites confusionensis, Kashmirites stepheni, ?Xiaoqiaoceras americanum, Minersvillites farai, Inyoites beaverensis, Meekoceras olivieri, Meekoceras millardense, Vercherites undulatus) are also described.

Introduction

The aftermath of the Permian–Triassic mass extinction is receiving more and more attention from the earth science community. However, biostratigraphically controlled paleontological data are often lacking and insufficient on a global scale to produce realistic models for the Early Triassic recovery. Significant progress at a large temporal and spatial scale is obtained using new databases grounded on primary data from the field and carefully revised taxonomy combined with recently published radiometric ages (e.g., Brayard et al. 2009c; Romano et al. 2013). Parallel to the global-scale approach, the pace of the recovery and underlying evolutionary mechanisms also need to be precisely studied on a more detailed regional scale. However, highly resolved temporal data remain rare for the Early Triassic. For instance, the taxonomic revision and detailed biostratigraphy of new ammonoid faunas from the Northern Indian Margin yield an unprecedented high resolution zonation that demonstrates surprisingly high evolutionary rates and thus confirms the explosive rediversification and high level of diversity attained by these cephalopods during the Smithian (Brayard et al. 2009c; Brühwiler et al. 2010a). Indeed, this time-interval is crucial since it records on a worldwide scale the main rediversification of several marine organisms only 1–2 myr after the mass extinction (e.g., Brayard et al. 2006, 2009c, 2011b; Orchard 2007), the reappearance of many Lazarus taxa among bivalves, gastropods and ammonoids (Brayard et al. 2007a; Kaim et al. 2010; Hautmann and Nützel 2005; Nützel 2005), and the return of some large-size taxa (Brayard et al. 2010, 2011a). Thus, an understanding of the mechanisms underlying the Early Triassic biotic recovery requires an accurate and robust Smithian regional biostratigraphical framework that may have worldwide correlation. Our recent field investigations of the Lower Triassic Thaynes and Moenkopi Groups in western, central and southern Utah have led to the recognition of several new Smithian ammonoid assemblages; they allow the construction of a new detailed biostratigraphical scheme for the low latitudes in eastern Panthalassa. In this paper, we mainly focus on the taxonomy, biostratigraphy and correlation of these new ammonoid assemblages. Paleo(bio)geographical and phylogenetic implications as well as correlation across latitudes and Panthalassa are also discussed.

Geological settings

The Sonoma Foreland Basin of western USA represents a unique key study area located at a near-equatorial position in eastern Panthalassa during the Early Triassic (Fig. 1). Smithian marine deposits are widely distributed within a large area covering Wyoming, Idaho, Utah and Nevada. These deposits generally contain abundant fossils, but a detailed regional biostratigraphical zonation has never been proposed for this substage (Silberling and Tozer 1968).

Fig. 1
figure1

Present-day (a) and Early Triassic (b) locations of the western USA basin and sampled sections in Utah

The alternating limestones and shales of the Lower Triassic Thaynes Group (sensu Lucas et al. 2007b) reflect deposition within the relatively shallow Sonoma Foreland Basin. Outcrops with different lithologies of these rocks can be widely seen from Idaho to Utah. These marine sedimentary deposits thin from the northwest to southeast across Utah, where they interfinger with the terrestrial sediments of the Moenkopi Group (sensu Lucas et al. 2007b). Deposits of the Thaynes Group roughly include both the Smithian and the Spathian substages. They are mostly renowned for mass occurrence or exceptional preservation of ammonoids (e.g., Brayard et al. 2009a; Gardner and Mapes 2000; Guex et al. 2010; Jenks 2007; Jenks et al. 2010, 2013; Kummel and Steele 1962; Silberling and Tozer 1968; Stephen et al. 2010). In this work, we focus on Smithian sedimentary successions from western, central and southern Utah in the Confusion Range, Pahvant Range, Star Range, Mineral Mountains, Kanarraville, Cedar City, Torrey and San Rafael Swell areas (Fig. 1).

Some of these Lower Triassic exposures and their ammonoid faunas such as within the Confusion Range have already been described in a very general sense, but the Smithian and especially its lowermost part have never been detailed (Bacon 1948; Collinson et al. 1976; Guex et al. 2010; Hose and Repenning 1959; Newell 1948; Silberling and Tozer 1968). Accurate Smithian biostratigraphical data regarding the other localities are much scarcer and often diluted or repeated among different studies (Baetcke 1969; Blakey 1973, 1974, 1977, 1979; Crosby 1959; Davis 1983; Dean 1981; Gilluly and Reeside 1928; Hintze and Davis 2003; Lucas et al. 2007a, b; Nielson 1991; Smith et al. 1963; Stewart et al. 1972).

All sections were measured within the lower portion of the Thaynes or Moenkopi Groups and nearly all contain numerous fossiliferous beds (Figs. 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13). These sections are rather similar in their upper parts in terms of lithological succession although deposits are slightly diachronous, thus highlighting the southward transgression of the sea within the basin during the Smithian (e.g., Paull and Paull 1993). All sections are relatively thick, indicating high sedimentation rates, but thickness also varies considerably from section to section. This variation probably represents deposition of sediments on a complex paleo-relief formed during the Late Permian–earliest Triassic transition (Collinson et al. 1976; Dean 1981). Ammonoids were systematically collected bed by bed, and though generally poorly preserved and often not measurable in the lowermost Smithian beds, they are abundant in the upper beds of all measured sections. Not all studied sections are depicted here, but each illustrated section log corresponds to the best biostratigraphical succession of the region.

Fig. 2
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Distribution of ammonoid taxa in the Confusion Range section (CR in Fig. 1). Open dots indicate occurrences based only on fragmentary or poorly preserved material. Perm. Permian, Dien. Dienerian, P.K. Preflorianites–Kashmirites beds, I.b. Inyoites beaverensis sp. nov. beds, O. Owenites beds, A.k. Anasibirites kingianus beds, Co oldest Smithian conodont occurrence within the section

Fig. 3
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Panorama of the main Confusion Range section showing ammonoid bed locations

Fig. 4
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Distribution of ammonoid taxa in the Pahvant Range section (PR in Fig. 1). Open dots indicate occurrence based only on fragmentary or poorly preserved material. Abbreviations as in Fig. 2. Fle. Flemingites sp. indet. bed, M.m. Meekoceras millardense sp. nov. bed, M.o. Meekoceras olivieri sp. nov. beds, R.e. Radioceras aff. evolvens beds

Fig. 5
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Panorama showing the location of part of the lower ammonoid beds within the main Pahvant Range section

Fig. 6
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Distribution of ammonoid taxa in the Mineral Mountain section (MM in Fig. 1). Open dots indicate occurrence based only on fragmentary or poorly preserved material. Abbreviations as in Figs. 2 and 4. Xe Xenoceltitidae gen. indet. A beds, V.u. Vercherites undulatus sp. nov. bed

Fig. 7
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Distribution of ammonoid taxa in the Star Range section (SR in Fig. 1). Abbreviations as in Figs. 2, 4 and 6

Fig. 8
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Distribution of ammonoid taxa in the Cedar City area (CC in Fig. 1). Open dots indicate occurrence based only on fragmentary or poorly preserved material. Abbreviations as in Figs. 2, 4 and 6

Fig. 9
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Distribution of ammonoid taxa in the Kanarraville section (KAN in Fig. 1). Open dots indicate occurrence based only on fragmentary or poorly preserved material. Abbreviations as in Figs. 2, 4 and 6

Fig. 10
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Distribution of ammonoid taxa in the Torrey area (TO in Fig. 1). Open dots indicate occurrence based only on fragmentary or poorly preserved material. Abbreviations as in Figs. 2, 4 and 6

Fig. 11
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Distribution of ammonoid taxa in the San Rafael Swell (SRS in Fig. 1). Abbreviations as in Figs. 2, 4 and 6

Fig. 12
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Biostratigraphical correlation between the studied sections illustrating the diachronism of sedimentary deposits

Fig. 13
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Late Smithian deposits of the Anasibirites kingianus beds at different studied localities. a Confusion Range; b Mineral Mountains; c Torrey area (left A. kingianus is ~10 cm in diameter); d, e Kanarraville section (Wasatchites perrini is illustrated in d); f, g Eumorphotis beds representing the Smithian–Spathian transition in the Mineral Mountains (f) and Kanarraville sections (g)

Classical regional Smithian biostratigraphy

The Meekoceras gracilitatis Zone

The most famous ammonoid beds of the Early Triassic and of the Thaynes Group are probably the Meekoceras gracilitatis Zone. This long-recognized zone, originally described from southeastern Idaho [Peale in White (1879)], is commonly used as a regional Smithian time-marker. It also represents the most diversified Smithian ammonoid fauna within the eastern Panthalassic low-paleolatitudes (Kummel and Steele 1962; Silberling and Tozer 1968; Smith 1932). In the USA, older fossiliferous Lower Triassic outcrops are rare (e.g., Candelaria and Dinwoody Formations) and often not well dated (Ware et al. 2011). Triassic deposits are also often considered to unconformably overlie Permian rocks with a major sedimentary hiatus (e.g., Hose and Repenning 1959). Within this scheme, the M. gracilitatis Zone is essential because it serves as one of the first, easily accessible macrofossil time-markers for the Early Triassic. However, this well-known index species displays a tabulate, relatively involute and compressed geometry that is frequent among Smithian ammonoids. A major problem, therefore, is to correctly identify true occurrences of M. gracilitatis. For instance, reports of several successive beds with Meekoceras sp. or M. gracilitatis throughout a thick outcrop are not rare (e.g., Crosby 1959; Davis 1983; Dean 1981, Hintze and Davis 2003), and these discrepancies must be clarified to obtain precise age calibration of the considered section.

Based on ammonoid faunas from California (e.g., Union Wash), Nevada (Phelan Ranch), SE Idaho and the work of Mathews (1929) in Utah, Smith (1932) proposed subdivisions for this regional biostratigraphical interval as follows in ascending order: the Pseudosageceras subzone, Owenites subzone and Anasibirites subzone. This biostratigraphical terminology was customarily accepted until the work of Kummel and Steele (1962), who suggested the use of the twofold subdivision consisting of the M. gracilitatis and Anasibirites kingianus Zones, in ascending order.

Recent biostratigraphical improvements

Despite a few studies of the M. gracilitatis Zone (Kummel and Steele 1962; Silberling and Tozer 1968), ammonoid workers have only recently suggested that this zone (a) represents only the middle/late Smithian; and (b) can be subdivided into supplementary different subzones and beds that have exact trans-Panthalassic correlatives (Brayard et al. 2009a; Jenks et al. 2010; Stephen et al. 2010). For instance, Jenks et al. (2010) recently highlighted that the M. gracilitatis Zone is essential for reasonably precise correlation between eastern and western Panthalassa (e.g., South China), and between low and high latitudes (British Columbia and the Canadian Arctic). The co-occurrence of several ammonoid genera on opposite sides of Panthalassa at that time indicates significant faunal exchange during the Smithian (Brayard et al. 2007b, 2009b; Jenks et al. 2010).

Brayard et al. (2009a) and Stephen et al. (2010) recently discussed cephalopod occurrences within the uppermost Smithian beds of the Confusion Range. They refined the previous local zonation proposed by Hose and Repenning (1959), and identified within the upper part of the M. gracilitatis Zone in ascending order, the Inyoites oweni beds, and the Anasibirites kingianus beds. In particular, they reported characteristic occurrences of A. kingianus, Wasatchites perrini and Xenoceltites sp. at the top of the section (bed 13), and more diverse assemblages below (beds 9–12) including I. oweni, Wyomingites arnoldi, Churkites noblei, Guodunites hooveri, Owenites koeneni, Pseudosageceras multilobatum, Aspenites acutus, Lanceolites bicarinatus, Juvenites septentrionalis, ?Kashmirites intermontanus, an ussuriid, and an unidentified proptychitid. Based on the occurrence of O. koeneni and I. oweni, Brayard et al. (2009a) and Stephen et al. (2010) defined the late–middle Smithian I. oweni beds in the uppermost part of the Owenites koeneni subzone and also recognized that: (a) the uppermost part of the M. gracilitatis beds and I. oweni beds correlate with the Owenites beds (middle Smithian) of the Tethyan paleoequatorial zonation; and (b) the I. oweni beds correlate with the Inyoites horizon in South China (Brayard and Bucher 2008).

The initial in-depth study of the Confusion Range by Hose and Repenning (1959) did not report ammonoid faunas from the lowermost Smithian levels. Several additional beds with ammonoids are herein described that characterize the early (but not earliest) and middle Smithian. Griesbachian or Dienerian ammonoid faunas have not been discovered. However, marine late Griesbachian?/Dienerian deposits do occur a few meters above Late Permian beds as shown by the occurrence of the bivalve Claraia (Fig. 2, R. Hofmann ongoing work; see McRoberts 2010 for temporal distributions of Early Triassic bivalves). These beds were deposited on an inherited complex Permian topography as suggested by the presence of breccias, conglomerates and normal faults underlying the Lower Triassic deposits. This emersion and erosion phase is overlain by microbialites characterized by small stromatolitic structures. Younger ammonoid faunas of early Spathian age also occur within this area at Cowboy Pass, and were included in a recent revision by Guex et al. (2010).

This work also complements recent reports of the occurrence of the late Smithian Anasibirites fauna at several sites in southwestern and southeastern Utah (e.g., Lucas et al. 2007a, b). For instance, ammonoid assemblages from the Pahvant Range and Mineral Mountains described herein provide a significant geographic link between localities to the east and south and to the west and north. Interestingly, ammonoids typical of the middle Smithian Meekoceras fauna have usually been assumed to be absent in the correlative Timpoweap and Sinbad Limestone localities to the southwest and southeast, respectively. Therefore, the occurrence of the Meekoceras fauna in the Pahvant Range until now has been the farthest southeast that this fauna has been reported in Utah. However, we newly report herein the occurrence of several taxa of the Meekoceras fauna (M. gracilitatis, Juvenites aff. spathi, Guodunites hooveri, Churkites noblei, Xenoceltites sp. indet.) within the lower and middle units of the Sinbad Limestone in the Torrey area, indicating that near-maximum extent of the Smithian sea in the southeastern part of the basin was reached earlier than previously thought (middle Smithian instead of late Smithian).

New biostratigraphical subdivisions

We provide here for the first time a comprehensive distribution of ammonoid faunas throughout the Smithian of the Thaynes and Moenkopi Groups in Utah, thus expanding and refining previous biozonations. No formal zone names are introduced since we currently prefer to use the terms “beds” or “assemblages” to describe the local faunal sequence. Eight new early–middle Smithian ammonoid assemblages are described; the new Smithian succession encompasses 12 subdivisions (Fig. 14). In furtherance of the work of Brayard et al. (2009a) and Stephen et al. (2010), we herein report the occurrence of several new species from the middle and late Smithian. A synthetic range chart of genera is given in Fig. 15.

Fig. 14
figure14

Central and Southern Utah ammonoid zonation and correlation with other Smithian successions. Spa. Spathian, Dien. Dienerian, PR Pahvant Range, MM Mineral Mountains

Fig. 15
figure15

Synthetic range chart of Smithian ammonoid genera from central and southern Utah

Vercherites undulatus sp. nov. bed

This assemblage is found only in the Mineral Mountains. It is probably the oldest known Smithian ammonoid fauna of the Thaynes Group. It is characterized by the unique occurrence of Vercherites undulatus sp. nov., which has not been found elsewhere. An exact correlation with other Panthalassic or Tethyan localities is uncertain (Figs. 12, 14, 15), but our specimens are similar to some late Dienerian/early Smithian proptychitids from the Salt Range (Pakistan) such as Vercherites (Brühwiler et al. 2012c), and thus are provisionally considered to be the oldest assemblage found in the studied area. A diagnostic Smithian conodont species (Furnishius triserratus) was discovered in the same bed confirming the Smithian age of the rocks.

Radioceras aff. evolvens beds

These beds are characterized by the unique occurrence of the rare involute taxon: Radioceras aff. evolvens. This subdivision was observed only within the Pahvant Range. It is probably younger than the Vercherites undulatus sp. nov. bed, when compared with ammonoid successions found in the North Indian Margin (Brühwiler et al. 2010a). It also has no exact worldwide correlative.

Meekoceras olivieri sp. nov. beds

These beds are characterized by the association of the prionitid Meekoceras olivieri sp. nov. with a possible flemingitid. This assemblage, documented only in the Pahvant Range, may be a correlative of early Smithian flemingitid faunas from the Salt Range (Brühwiler et al. 2012c).

Meekoceras millardense sp. nov. bed

This subdivision from the Pahvant Range contains only the rare involute taxon Meekoceras millardense sp. nov. This bed has no exact worldwide correlative.

Preflorianites–Kashmirites beds

This assemblage is relatively well documented and contains a rather diverse Smithian fauna with Kashmirites sp., Preflorianites toulai, Arctoceras tuberculatum, and Pseudosageceras multilobatum. The fauna is also marked by the first occurrence of true Meekoceras gracilitatis. This subdivision is probably located near the early/middle Smithian boundary (Figs. 14, 15). Indeed, it may correlate with

  • the early Smithian Kashmirites kapila beds of South China (Brayard and Bucher 2008) and Kashmirites sp. indet. beds of South Tibet (Brühwiler et al. 2010b), as it corresponds to the first regional appearance of Kashmirites,

  • and possibly also to the lowermost part of the Flemingites rursiradiatus beds of South China (Brayard and Bucher 2008), Oman (Brühwiler et al. 2012a) and the Salt Range (Brühwiler et al. 2012c), because it contains Arctoceras and Preflorianites.

Inyoites beaverensis sp. nov. beds

This assemblage, present in the Pahvant Range, Confusion Range and Mineral Mountains, is characterized by the occurrence of Inyoites beaverensis sp. nov., Kashmirites utahensis sp. nov., Anaflemingites sp. indet., Aspenites acutus and Meekoceras gracilitatis. This fauna may correlate in part with the Flemingites rursiradiatus beds from South China, Oman and the Salt Range (op. cit.). This is the oldest known occurrence of the genus Inyoites in the world.

Flemingites sp. indet. bed

This bed is characterized by the occurrence of an undetermined species of Flemingites. Since it is found just below the first occurrence of Owenites in the Pahvant Range, it may correspond to the uppermost part of the Flemingites rursiradiatus beds from South China, Oman and the Salt Range (op. cit.).

Owenites beds

These beds, characterized by the occurrence of several Owenites species, are documented from all studied sections, except the San Rafael Swell area. These assemblages, previously described by Brayard et al. (2009a) and Stephen et al. (2010), are probably the most diverse within Utah, and our extensive collections allow us to augment previous occurrence lists. These beds commonly contain O. cf. koeneni, O. carpenteri, Meekoceras gracilitatis, Churkites noblei, Guodunites hooveri, Inyoites oweni, Juvenites cf. thermarum, Aspenites acutus, Pseudosageceras multilobatum, Hedenstroemia kossmati, Lanceolites compactus, L. bicarinatus, Dieneroceras dieneri, Xenoceltites cordilleranus, Parussuria compressa and an indeterminate prionitid. Wyomingites arnoldi, a taxon previously reported from these beds (Stephen et al. 2010), is herein newly assigned to Dieneroceras dieneri. A major portion of this fauna consists of widely occurring taxa known from several localities within the paleoequatorial belt: South China (Brayard and Bucher 2008), South Tibet (Brühwiler et al. 2010b), Salt Range (Brühwiler et al. 2012c), and Oman (Brühwiler et al. 2012a). This characteristic middle Smithian assemblage can be subdivided into different successive faunas. The co-occurrence of Inyoites oweni and O. carpenteri distinguishes the uppermost fauna and defines the I. oweni horizons (Brayard et al. 2009a; Stephen et al. 2010), which can be correlated with the Inyoites horizon from South China (Brayard and Bucher 2008) and the Nyalamites angustecostatus beds from Spiti, Salt range, and Oman (Brühwiler et al. 2012a, b, c). In the Pahvant Range, Hanielites (H. sp. indet.) is probably present but restricted to a single bed, thus suggesting the existence of a lower eponymous subdivision. The same applies in the Mineral Mountains where a new arctoceratid, Minersvillites farai gen. nov., sp. nov. co-occurs with Submeekoceras muschbachanum and Churkites noblei at the base of the Owenites beds. If the occurrence of Hanielites is confirmed, this bed can be correlated with the Hanielites horizon of South China and the upper part of the Nammalites pilatoides beds of South Tibet (Brühwiler et al. 2010b). Minersvillites farai gen. nov., sp. nov. is closely related to Brayardites, which is known from the Salt Range, South Tibet and Spiti, and thus could constitute an approximated correlative bed. It should also be noted that ussuriids such as Parussuria, which occur earlier in South China than in Utah, define the first subdivision of the Owenites koeneni beds (Brayard and Bucher 2008).

Anasibirites kingianus beds

These late Smithian beds are characterized by Anasibirites kingianus associated with Wasatchites perrini, and several species of Arctoprionites, Hemiprionites and Xenoceltites. This low-diversity fauna is recognized worldwide and corresponds to a major global ammonoid extinction event (Brayard et al. 2006, 2009c), coinciding with the onset of marked events in the geochemical, sedimentological, palynological and climate records (Galfetti et al. 2007a, b, c; Hermann et al. 2011; Romano et al. 2013). All studied localities display different facies (Fig. 13a–e) for this short time-interval, but they also exhibit significant sedimentological evidence (e.g., shallow and proximal facies such as red beds) indicating an extremely rapid regression spanning the Smithian/Spathian boundary after the deposition of the Anasibirites kingianus beds.

Xenoceltitidae gen. indet. A beds

These beds commonly contain common specimens of Xenoceltitidae gen. indet. A. They represent the latest Smithian and probably correlate with the Glyptophiceras sinuatum beds from South Tibet and the Salt Range (Brühwiler et al. 2010b, 2012c), which generally contain an abundant xenoceltitid fauna with Glyptophiceras and Xenoceltites species. This zone is here reported for the first time from Utah, but it also has previously been reported from Crittenden Springs, Nevada (Jenks et al. 2010). However, the extremely poor preservation of our specimens precludes any definitive assignment to these taxa. Pseudosageceras augustum, another latest Smithian diagnostic taxon, has not been documented from the studied area. However, Hedenstroemiidae gen. indet. A, an ammonoid somewhat similar to P. augustum, also occurs within these beds.

Discussion

Global and basinal biostratigraphical correlations

This work shows that the ammonoid succession in western Utah is quite uniform for the late–middle and late Smithian. The updated biozonation for this interval is to a certain extent also recognized worldwide, thus allowing for more precise correlation than previously achieved. In contrast, many of the sections were found to contain new but different assemblages in the early and early–middle Smithian transition. On the one hand, this sometimes precludes precise correlation within the western USA Basin and with other basins of different paleolatitudes for this time-interval. On the other hand, it supports previous works that suggested early–middle Smithian ammonoids were more endemic and latitudinally restricted than during the late Smithian (Brayard et al. 2006, 2007b, 2009b; Jenks 2007; Jenks et al. 2010). Long-distance correlation across latitudes is only possible during the late Smithian, when genera such as Anasibirites, Wasatchites or Xenoceltites are fully cosmopolitan (Fig. 14), concomitant with a marked extinction probably linked to major oceanographic and/or climate changes (e.g., Brayard et al. 2009c; Galfetti et al. 2007c; Romano et al. 2013).

After extensive fieldwork, it has become apparent to the authors that beds with very abundant bivalves above the Anasibirites kingianus beds usually mark the Smithian–Spathian transition in central and southern Utah. In numerous places, this regional bloom is characterized by large Eumorphotis (e.g., E. virginensis, E. ericius, E. multiformis; Fig. 13f, g). Although they may be marginally diachronous, these deposits (“bivalve transition beds” or “Eumorphotis beds” in Figs. 2, 4, 6, 7, 8, 9, 10, 11) probably reflect a significant faunal event within the basin and may serve as a regional time-marker for the earliest Spathian. A formal link between this regional bivalve bloom and the end-Smithian extinction has not yet been determined, but this study is beyond the scope of the present paper.

On the use of Meekoceras gracilitatis for regional biozonation

M. gracilitatis appears to be a relatively long-ranging species that occurs mainly in the early/middle Smithian and thus, it is not very useful for precise biostratigraphical zonation and correlation. Early Triassic ammonoid workers are well aware that the Smithian contains numerous homeomorph taxa (e.g., Kummel and Steele 1962). We illustrate herein several taxa exhibiting a close resemblance to M. gracilitatis that characterize the regional lowermost Smithian, thus questioning some previous taxonomic assignments and zonations. Also, weathered specimens of such taxa as Anasibirites, Wailiceras, Hedenstroemia or Radioceras may easily be confused with M. gracilitatis. This species is therefore not well suited to characterize the entire time-interval as is usually the case. Thus, whenever possible, it is recommended not to use M. gracilitatis as a time-marker, but instead, we suggest the use of more abundant and short-ranging taxa with specific and easily recognizable morphologies (e.g., Inyoites oweni or Preflorianites toulai) to obtain precise ages for the Smithian in Utah.

On the age and correlation of Smithian formations in Utah

According to the newly obtained ammonoid succession, it appears obvious that sedimentary deposits of established stratigraphic units usually assumed to be time-equivalent within central and southern Utah are diachronous (Fig. 12), which modifies previously suggested correlative schemes such as that by Goodspeed and Lucas (2007). Thus, caution should be taken when using formation names to designate a specific time-interval, especially when it applies to regional and worldwide correlation.

Within Utah, the best known and most widely used Smithian formation is the “Sinbad Limestone”. It was defined in the San Rafael Swell area (Gilluly and Reeside 1928; Fig. 1) and then extrapolated to southwestern Utah. This formation has been often considered as entirely of Smithian age in many recent studies (e.g., Fraiser and Bottjer 2004). However, ammonoid occurrences clearly indicate that only the lower ~1/4 of this thick unit at the type-locality is actually end-Smithian (Anasibirites kingianus beds, Fig. 11), and that the rest of the unit is likely earliest Spathian (see also Goodspeed and Lucas 2007). The “Sinbad Limestone” is also widely found in the Torrey area (Dean 1981; Fig. 1). However, although sedimentary successions are rather similar to those of the San Rafael Swell area, ammonoids indicate a middle-to-late Smithian age for this unit in the Torrey area (Fig. 10). In southwestern Utah (Cedar City, Kanarraville and Virgin areas), the “Timpoweap Member” is usually considered as a time-equivalent and junior synonym of the “Sinbad Limestone” (Lucas et al. 2007b). Nevertheless, ammonoids indicate a middle-to-late Smithian age for this unit. Thus, it can only be correlated with the “Sinbad Limestone” of the Torrey area, and not (or only partly) with its type-locality in the San Rafael Swell area. Depending on the studied area in Utah, authors should therefore clearly specify the age of the section by means of ammonoids or conodonts, if possible, and not refer to just the “Sinbad Limestone” designation, which may either be middle-to-late Smithian or span the end-Smithian/Spathian transition.

Dating and monitoring of the Smithian transgression within Utah

The newly obtained ammonoid succession allows us to closely follow the advancing sea during the Smithian. Our scenario fits well with the global Smithian reconstruction previously proposed by, e.g., Carr and Paull (1983), Collinson et al. (1976), Collinson and Hasenmueller (1978) and Paull and Paull (1993) based on conodont zonation and sedimentological evidence. However, our data provide a scenario with a greater time resolution for the Smithian. We thus define the five following main steps (Fig. 16):

Fig. 16
figure16

Schematic advance of the sea within Utah during the Smithian, based on ammonoid data. a Localities used for the reconstruction (same sites and abbreviations as in Fig. 1, with the addition of other known outcrops where ammonoids were collected; BL Bear Lake area, CS Crittenden Springs, PR Phelan Ranch, WM Wasatch Mountains, HC Hurricane Cliffs; e.g., Hofmann et al. 2013; Hyatt and Smith 1905; Jenks 2007; Jenks et al. 2010; Kummel and Steele 1962; Smith 1932). b Schematic extent of the Smithian open marine depositional facies (based on Carr and Paull 1983; Collinson and Hasenmueller 1978; Paull and Paull 1993). Detailed evolution of the transgression: c from the Vercherites undulatus sp. nov. bed up to the Preflorianites–Kashmirites beds; d during deposition of the Preflorianites–Kashmirites beds and Inyoites beaverensis sp. nov. beds; e during deposition of the Owenites beds; f during deposition of the Anasibirites kingianus beds

  1. 1.

    Earliest Smithian ammonoid faunas are apparently absent from Utah. However, supposedly time-equivalent deposits corresponding to shallow environments and occasional microbial-sponge reefs (Figs. 2, 4, 6, 10; Brayard et al. 2011b) represent the very beginning of the Smithian transgression within the basin. These early Smithian deposits are mainly found in central Utah (Pahvant Range, Mineral Mountains). This area is also the first to record the presence of ammonoid faunas (Vercherites undulatus sp. nov. bed up to the Preflorianites–Kashmirites beds); hence, we interpret it as corresponding to true open marine conditions. Following this hypothesis, the transgression appears to proceed southward along a central corridor within Utah, rather than spreading out from the basin depocenter in all directions. In particular, the transgression seems not to have reached some neighboring localities such as Crittenden Springs in Nevada, the Confusion Range or the Wasatch Mountains in Utah. This indicates that these localities may have been part of a complex basinal paleogeography with an irregular shoreline inherited from the Permian topography. Furthermore, it suggests that the pathway of the early Smithian transgression may have also resulted from a combination of (a) the subsidence of the foreland basin with the deeper parts (down through central Utah) possibly marking the axis of the foreland basin (the location of which is often estimated with great uncertainty; see Dickinson 2006); and (b) paleotopographic highs on each side of the basin;

  2. 2.

    The transgression reached the Confusion Range during the time of deposition of the Preflorianites–Kashmirites beds and Inyoites beaverensis sp. nov. beds. However, during this time, the open sea was restricted to the previous flooded area and did not move further South enough to record ammonoids and true open marine facies in this area. The accommodation space in this part of the basin was already sufficient to sustain thick deposits. Areas in southern Utah may have been partly isolated from the transgression by the existence of a wide epeiric platform that dampened incoming waves, or by being positioned behind a barrier, or within a restricted embayment. Incidentally, such a fragmented paleogeographic setting may well have led to the development of relatively isolated paleobiogeographic areas with island-like features such as the local occurrence of unbalanced benthic faunas with some remarkably small-sized species. This hypothesis, which remains to be further tested, would offer an interesting alternative scenario to the henceforth refuted global Early Triassic “Lilliput effect” (Brayard et al. 2010, 2011a);

  3. 3.

    The Owenites beds probably represent a new advancing phase of the transgression within the basin, reaching previously discussed western and southern areas. Almost all parts of the basin are thus inundated slightly earlier than previously thought (middle Smithian instead of late Smithian);

  4. 4.

    The maximum extent of the transgression was reached during deposition of the Anasibirites kingianus beds (late Smithian) when all localities were characterized by this assemblage, especially the southwesternmost and southeasternmost parts of the basin. All studied localities display sedimentological evidence (e.g., shallow and proximal deposits such as red beds) of an extremely rapid regression spanning the Smithian/Spathian boundary after deposition of the Anasibirites kingianus beds;

  5. 5.

    Following this event, a new early Spathian marine transgression is marked by marine faunas such as Tirolites or nautiloid occurrences within well-known deposits such as the Virgin limestone in southwestern Utah (e.g., Hofmann et al. 2013). However, in Utah this Spathian transgression did not reach the maximum extent of the Smithian sea, since it is not recorded on the eastern side of the basin (Carr and Paull 1983; Collinson and Hasenmueller 1978; Paull and Paull 1993).

Conclusion

Intensive sampling within central and southern Utah has led to the recognition of 10 new Smithian ammonoid taxa (one new genus and nine species) and 12 successive associations. The resulting new biostratigraphical succession is therefore more precise than the previous twofold subdivision suggested by Kummel and Steele (1962). This new faunal sequence can be correlated in detail with several worldwide localities (Fig. 14) thanks to the presence of many trans-Panthalassic (middle Smithian) and cosmopolitan (late Smithian) taxa. However, a detailed correlation for the early–middle Smithian transition remains hampered by poor ammonoid preservation and a high degree of endemism, as well as an insufficient knowledge of ammonoid faunas collected from the western USA basin. Earliest Smithian ammonoid faunas are apparently absent. Meekoceras gracilitatis, the commonly used Smithian ammonoid index, is here shown to be a long-ranging genus and a rather good indication of the middle Smithian interval. However, this species can be easily confused with other taxa such as the prionitid genera Anasibirites or Hemiprionites, especially in the case of poor preservation. Therefore, we call for the use of more abundant, short-ranging taxa with specific and easily recognizable morphologies (e.g., Inyoites oweni or Preflorianites toulai) to precisely characterize ages of the various Smithian sedimentary successions in Utah.

This new biostratigraphical scheme draws attention to the highly irregular nature of the Smithian basinal paleogeography that most probably is due to an inherited complex Permian topography. It also allows us to closely follow the southward Smithian open sea transgression within Utah. The transgression reached its maximum extent during the late Smithian (Anasibirites kingianus beds of the Cedar City, Kanarraville and San Rafael Swell areas), but arrived earlier than previously thought in most studied localities (e.g., Radioceras aff. evolvens beds in the Pahvant Range, and base of the Owenites beds in the Torrey area).

Systematic paleontology (Brayard, Bylund and Jenks)

Systematic descriptions follow the ammonoid classification of Tozer (1981, 1994) and Brayard and Bucher (2008), and then further refined by Brühwiler et al. (2012a, b, c). The quantitative morphological ranges for each species are described (when permitted by preservation) using the four classical geometrical parameters of the ammonoid shell: diameter (D), whorl height (H), whorl width (W) and umbilical diameter (U). H, W and U are plotted in absolute values and ratios (H/D, W/D and U/D). Repository of figured and measured specimens is abbreviated UBGD (Université de Bourgogne, Géologie Dijon). Scale bar on illustrated specimens is 10 mm unless otherwise indicated.

Order Ammonoidea Zittel, 1884

Suborder Ceratitina Hyatt, 1884

Family Xenoceltitidae Spath, 1930

Genus Xenoceltites Spath, 1930

Type species Xenoceltites subevolutus = Xenodiscus cf. comptoni (non Diener) Frebold, 1930

Xenoceltites cordilleranus (Smith, 1932)

Fig. 17a–x

Fig. 17
figure17

Xenoceltites cordilleranus (Smith 1932). All from the Owenites beds, Inyoites oweni horizons, Smithian; a, b UBGD 275000, UBGD 275001, respectively, loc. DV1-9, Pahvant Range; cf UBGD 275002, loc. DH1-12, Confusion Range; g, h UBGD 275003, Loc. DH1-12, Confusion Range; i, j UBGD 275004, loc. DH1-11, Confusion Range; ko UBGD 275005, loc. DH1-12, Confusion Range; o scale bar is 5 mm (H = 7.5 mm); p, q UBGD 275006, loc. DH1-12, Confusion Range; r UBGD 275007, loc. DH1-11, Confusion Range; sv UBGD 275008, loc. DH1-11, Confusion Range; w UBGD 275009, loc. DH1-11, Confusion Range

1932 Xenodiscus cordilleranus; Smith, p. 43, pl. 24, figs. 21-29.

1932 Xenodiscus intermontanus; Smith, p. 44, pl. 24, figs. 10-20.

p 1932 Xenodiscus nivalis; Smith, p. 44, pl. 56, figs. 6-9 [only].

? 1979 Dieneroceras knechti; Nichols and Silberling, pl. 1, figs. 22-26.

2010 ?Kashmirites intermontanus; Stephen et al., figs. 5e, f, h.

Occurrence Common in the Confusion Range [DH1-12, DH1-10/11] and Pahvant Range [DV1-9, DV1-8], Owenites beds, Inyoites oweni horizons. Not documented from the other studied sections.

Description Evolute, compressed platycone with a large intraspecific variation. Venter rounded or broadly arched with rounded shoulders forming rectangular to subquadratic whorl sections. Flanks almost parallel. Umbilicus wide, with moderately deep, perpendicular (inner whorls) to oblique (outer whorls) wall and rounded shoulders. Ornamentation varies from regularly distant, marked and slightly rursiradiate ribs on inner whorls to dense, rursiradiate and more variable strength ribs at maturity. Suture line ceratitic, with broad ventral saddle and a smaller umbilical saddle.

Measurements See Fig. 18. Estimated maximal size: ~5 cm.

Fig. 18
figure18

Scatter diagrams of H, W and U, and H/D, W/D and U/D for Xenoceltites cordilleranus (all specimens from the Confusion Range, Owenites beds, Inyoites oweni horizon)

Discussion See Brayard and Bucher (2008) for a discussion on Xenoceltites species assignments based on main morphological characteristics. X. cordilleranus is one of the older reported xenoceltitids since most of them occur worldwide within the Anasibirites kingianus beds. Xenodiscus hannai Mathews (1929) displays a similar coiling geometry and a similar coarse ornamentation type (Mathews’ specimens were reported as Xenodiscus nivalis in Smith 1932, pl. 79, figs. 1, 2). However, its ribs were described and illustrated as “nearly straight, slightly flexuous, radial” (Mathews 1929, p. 5). This species thus appears rather distinct from X. cordilleranus with its rursiradiate ornamentation. Moreover, an exact temporal occurrence of Xenodiscus hannai was not reported by Mathews.

Xenoceltites sp. indet. A

Fig. 19a–c

Fig. 19
figure19

ac Xenoceltites sp. indet. A., UBGD 275010, loc. DH1-13, Confusion Range, Anasibirites kingianus beds, Smithian; c scale bar is 5 mm (H = 10.6 mm); d Xenoceltitidae gen. indet. A., UBGD 275011, loc. MIA11, Mineral Mountains, Xenoceltitidae gen. indet. A beds, Smithian

? 2010 Xenoceltites sp.; Stephen et al., fig. 7d.

Occurrence Extremely rare in the Confusion Range, Anasibirites kingianus beds [n = 2; DH1-13]. Not documented from the other studied sections.

Description Shell geometry typical of the xenoceltitidae: evolute, compressed platycone with rounded venter, rounded ventral shoulders, and almost parallel flanks, becoming gently convergent on ventral shoulder. Umbilicus wide, with moderately deep, oblique wall and rounded shoulders. No ornamentation visible on our unique specimen at maturity. Very weak folds appear to be present on juvenile stages. Suture line apparently ceratitic, with a broad, deep lateral lobe and very small umbilical saddle.

Measurements See Table 1.

Table 1 Measurements of some Smithian ammonoids from Utah

Discussion The poor preservation of our specimen unfortunately prevents its attribution to a species. However, our specimen does not display distinctive marked ornamentation (ribs, bulges, constrictions) at maturity, thus differing from the other known species from late Smithian correlative beds of Guangxi, Salt Range, Spiti (X. variocostatus; see Brayard and Bucher 2008, Brühwiler et al. 2012b, c) or Spitsbergen (X. spitsbergensis; see Weitschat and Lehmann 1978). Although apparently slightly more evolute, the overall shape of our specimen invites more of a comparison with X. subevolutus from correlative beds of Spitsbergen (see Weitschat and Lehmann 1978) and Siberia (see Dagys and Ermakova 1990).

Xenoceltitidae gen. indet. A

Fig. 19d

Occurrence Common in the Mineral Mountains, Xenoceltitidae gen. indet. beds [n = 12; MIA11]. Not documented from the other studied sections.

Description Sampled specimens are all very poorly preserved, but coiling is moderately evolute with rounded venter and rounded ventral shoulders. Flanks probably parallel. Umbilicus often crushed, but with moderately deep, oblique wall and rounded shoulders. Ornamentation and suture line not preserved.

Measurements Not possible due to poor preservation. Estimated maximum size: ~7 cm.

Discussion The poor preservation of our specimens precludes any taxonomic assignment. However, they roughly resemble latest Smithian Xenoceltites or Glyptophiceras species such as X. variocostatus from South China or G. sinuatum from the Salt Range (e.g., Brayard and Bucher 2008; Brühwiler et al. 2012c). Another indirect indication of affiliation with the xenoceltitid group is its stratigraphic position above the Anasibirites kingianus beds, which elsewhere corresponds to the Glyptophiceras sinuatum beds and its xenoceltitid fauna.

Family Kashmiritidae Spath, 1934

Genus Preflorianites Spath, 1930

Type species Danubites strongi Hyatt and Smith, 1905

Preflorianites toulai (Smith, 1932)

Fig. 20a–h

Fig. 20
figure20

Preflorianites toulai (Smith 1932). All from the Preflorianites–Kashmirites beds, Smithian; a UBGD 275012, loc. DV2-3C, Pahvant Range; b UBGD 275013, loc. DH1-2, Confusion Range; ce UBGD 275014, loc. DH1-2, Confusion Range; fg UBGD 275015, loc. DH1-2, Confusion Range; g scale bar is 5 mm (H = 13.4 mm); h UBGD 275016, loc. DH1-2, Confusion Range; i Kashmirites utahensis sp. nov., UBGD 275017, loc. DV2-3E, Pahvant Range, Preflorianites–Kashmirites beds, Smithian, holotype

? 1922 Xenodiscus bittneri; Welter, p. 106, pl. 4, figs. 7, 8;

1932 Xenodiscus toulai; Smith, p. 45, pl. 25, figs. 1-3; pl. 53, figs. 9–12.

1932 Proteusites rotundus; Smith, p. 103, pl. 53, figs. 5–8.

1959 Preflorianites radians; Chao, p. 196, pl. 3, figs. 6–8.

1962 Preflorianites toulai; Kummel and Steele, p. 669, pl. 100, figs. 18–20; pl. 102, fig. 5.

? 1968 Preflorianites cf. radians; Zakharov, p. 137, pl. 27, figs. 5, 6.

1995 Preflorianites toulai; Shevyrev, p. 26, pl. 2, fig. 4.

2008 Pseudoceltites? angustecostatus; Brayard and Bucher, p. 18; pl. 3, figs. 1–7; text-fig. 19.

2012a Preflorianites radians; Brühwiler and Bucher, p. 15, pl. 1, figs. 8, 9; pl. 2, figs. 1–7.

Occurrence Rather common in the Confusion Range [DH1-0] and rare in the Pahvant Range [DV2-2, DV2-3], Preflorianites–Kashmirites beds. Not documented from the other studied sections.

Description Evolute conch with a compressed whorl section, but showing a wide range of intraspecific variation. Venter broadly to highly arched with rounded shoulders forming near-rectangular to ovoid whorl sections. Flanks slightly convex. Large, shallow umbilicus with an oblique wall and rounded shoulders. Ornamentation consists of regularly spaced, marked and radial ribs fading out towards the venter. Faintly sinuous, fine growth lines are sometimes barely perceptible. Suture line ceratitic, with deep lateral lobes, well-rounded saddles and very small umbilical saddle.

Measurements See Fig. 21. Estimated maximal size: ~9 cm.

Fig. 21
figure21

Scatter diagrams of H, W and U, and H/D, W/D and U/D for Preflorianites toulai (open symbols indicate measurable specimens from the Confusion Range and Pahvant Range, Preflorianites–Kashmirites beds [n = 5]; grey symbols indicate specimens from Nevada [n = 12], Caucausus [n = 2], Primorye [n = 4], South China [n = 21] and Oman [n = 7]; data respectively from Kummel and Steele 1962, Shevyrev 1995, Zakharov 1968, Brayard and Bucher 2008 and Brühwiler et al. 2012a)

Discussion The type species apparently differs from Preflorianites toulai by its angular venter that is seen only on the holotype (see Hyatt and Smith 1905). Its coiling features and ornamentation do not show any other divergence. Although specimens from beds that contain the type specimens of P. strongi at Union Wash are abundant, additional individuals presenting an angular venter were not illustrated or subsequently collected (A.B. personal observation). This therefore suggests that the original illustration of the type specimen entails a false characteristic. In this case, P. toulai should be synonymized with the type species. However, we prefer to retain the two erected species as we have not yet examined the holotype to check its diagnostic angular venter.

It has been commonly assumed that P. strongi and P. toulai differ from P. radians from South China (Chao 1959; see Brayard and Bucher 2008) and Oman (Brühwiler et al. 2012a) only by its slightly more involute coiling and an apparently smaller mature size. However, based on the new specimens from Utah, which exhibit a wide range of intraspecific variation and near identical measurements (Fig. 22), we hypothesize that these taxa are conspecific because we presently do not see any major difference that would justify erection of dissimilar species. P. cf. radians described from South China by Brayard and Bucher (2008) exhibits a weaker and slightly more sinuous ornamentation as well as a venter that may be more tabulate. However, its other shell characteristics fit well with the Preflorianites diagnosis. The wide range of variation of P. toulai in Utah may be partly explained by the Buckman’s first law of covariation, which Westermann (1966) coined to account for the varying degrees of intraspecific variation commonly observed in coiled ammonoids (e.g., Dagys and Weitschat 1993; Kennedy and Cobban 1976; Monnet and Bucher 2005; Monnet et al. 2010; Weitschat 2008).

Fig. 22
figure22

Box plots of H/D, W/D and U/D for Preflorianites toulai from Utah, Nevada and the Caucasus (this work, Kummel and Steele 1962 and Shevyrev 1995, respectively) and P. radians from Primorye, South China and Oman (Zakharov 1968, Brayard and Bucher 2008 and Brühwiler et al. 2012a, respectively)

Genus Kashmirites Diener, 1913

Type species Celtites armatus Waagen, 1895

Kashmirites utahensis sp. nov.

Fig. 20i

Holotype UBGD 275017 (Fig. 20i), loc. DV2-3E, Pahvant Range, Inyoites beaverensis sp. nov. beds, Smithian.

Derivation of name Species name refers to the State of Utah.

Diagnosis Rather thick, evolute and markedly ornamented kashmiritid differing from the type species by a shallower umbilicus and dense ribs on inner whorls becoming distant fold-like ribs on outer whorls.

Occurrence Extremely rare. One incomplete specimen found in the Pahvant Range within the Inyoites beaverensis sp. nov. beds [DV2-3E].

Description Evolute and rather thick shell with an apparent subtabulate or slightly arched venter. Ventral shoulders not well preserved, but flanks appear almost parallel. Umbilicus rather shallow with an inclined wall and rounded margins. Our unique specimen exhibits conspicuous, radial and dense ribs on inner whorls that are transformed on outer whorls into large, regularly spaced folds. Suture line unknown.

Measurements Not possible. Estimated maximum size: ~5 cm.

Discussion The overall shape of this species is close to most Kashmirites species, but mainly differs by its inclined umbilical wall and ornamentation that fades on outer whorls. This type of ornamentation resembles that of Kashmirites guangxiense described from South China (Brayard and Bucher 2008).

Kashmirites confusionensis sp. nov.

Fig. 23a–f

Fig. 23
figure23

af Kashmirites confusionensis sp. nov. All from loc. DH1-2, Confusion Range. Preflorianites–Kashmirites beds, Smithian; ac UBGD 275018, holotype; c scale bar is 5 mm (H = 10 mm); df UBGD 275019, paratype. gj Kashmirites stepheni sp. nov. All from the Preflorianites–Kashmirites beds, Smithian; g, h UBGD 275020, holotype, loc. DV2-2, Pahvant Range; i UBGD 275021, paratype, loc. DV2-2, Pahvant Range; j UBGD 275022, paratype, loc. SR21, Star Range

Holotype UBGD 275018 (Fig. 23a–c), loc. DH1-2, Confusion Range, Preflorianites–Kashmirites beds, Smithian.

Derivation of name Species name refers to the Confusion Range.

Diagnosis Large, evolute kashmiritid with a simplified suture line, an apparent arched venter and dense, regularly spaced ribs that do not fade away on outer whorls.

Occurrence Rather common in the Preflorianites–Kashmirites beds of the Confusion Range, but often only body chambers are preserved.

Description Large, evolute discoidal shell with an apparent arched venter. Venter appears more subtabulate on robust variant. Ventral shoulders rounded, with almost parallel flanks. Umbilicus large and moderately shallow with a vertical wall and rounded margins. Ornamentation consists of conspicuous, radial and regularly spaced ribs that do not fade on outer whorls. Ribs apparently do not cross the venter. Simplified ceratitic suture line with only two large lateral saddles.

Measurements See Table 1. Estimated maximum size: ~7 cm.

Discussion This species can be distinguished from other Kashmirites species by its simplified suture line architecture. It also mainly differs from K. utahensis sp. nov. by its regularly spaced ornamentation that does not fade on outer whorls. K. confusionensis sp. nov. may be easily confused with Preflorianites toulai if specimens are weathered.

Kashmirites stepheni sp. nov.

Fig. 23g–j

Holotype UBGD 275020 (Fig. 23g, h), loc. DV2-2, Pahvant Range, Preflorianites–Kashmirites beds, Smithian.

Derivation of name Species named after Daniel A. Stephen (Utah Valley University).

Diagnosis Rather compressed kashmiritid with an arched venter, an apparent egressively coiled final portion of mature body chambers and variable, conspicuous ribbing.

Occurrences Body chambers are common in the Pahvant Range [DV2-2] and Star Range [SR21] within the Preflorianites–Kashmirites beds.

Description Moderately evolute shell exhibiting apparent egression, that becomes less curved and straighter on body chambers. Whorl section rather rectangular with an apparent arched venter. Flanks almost parallel and gradually converging toward venter, whose ventral shoulders are indistinct. Umbilicus unknown as inner whorls are not preserved on our specimens. Umbilical wall appears high and slightly oblique with rounded shoulders. Ornamentation consists of conspicuous, radial and unevenly spaced ribs and plications fading on ventral margins. Rib strength changes during ontogeny with stronger ribs at maturity. Suture line unknown.

Measurements Not possible. Estimated maximum size: ~6 cm.

Discussion This new species mainly differs from other kashmiritid taxa by its arched venter, its irregular ornamentation and its unique apparent egressively coiled ending on large body chambers.

Genus Hanielites Welter, 1922

Type species Hanielites elegans Welter, 1922.

Hanielites sp. indet.

Fig. 24a–c

Fig. 24
figure24

ac Hanielites sp. indet., UBGD 275023, loc. DV2-6, Pahvant Range, Owenites beds, Smithian; dr Juvenites cf. thermarum (Smith 1927). All from the Owenites beds, Inyoites oweni horizons, Smithian; df UBGD 275024, loc. DH1-11, Confusion Range; gi UBGD 275025, loc. DH1-11, Confusion Range; jl UBGD 275026, loc. DH1-12, Confusion Range; mp UBGD 275027, loc. DH1-11, Confusion Range; p scale bar is 5 mm (H = 5 mm); q, r UBGD 275028, loc. DH1-12, Confusion Range

Occurrence Extremely rare. One incomplete specimen found in the Pahvant Range within the Owenites beds [DV2-6].

Description Moderately involute, compressed shell with an apparent arched venter. Ventral shoulders are rounded and flanks are parallel. Umbilicus shallow with a gently sloping wall and rounded margins. Ornamentation consists of slightly sinuous, radial ribs alternating with rare thin plications. Some ribs are projected forward near the ventral margin and may cross the venter. Other ribs fade before reaching the venter. Suture line unknown.

Measurements Not possible. Estimated maximum size: ~2.5 cm.

Discussion Our specimen exhibits a few characters reminiscent of Hanielites species from South China (see Brayard and Bucher 2008) such as the compressed shell and alternation of ribs and plications. However, it apparently differs from these species by the absence of a keeled or triangular venter, thus preventing a specific taxonomic assignment. The occurrence of Hanielites species is also rare in South China, but they are probably present in Utah within time-correlative horizons of the Owenites beds.

Family Melagathiceratidae Waagen, 1895

Genus Juvenites Smith, 1927

Type species Juvenites kraffti Smith, 1927

Juvenites cf. thermarum (Smith, 1927)

Fig. 24d–r

1927 Thermalites thermarum; Smith, p. 24, pl. 21, figs. 11–20.

1932 Prenkites depressus; Smith, p. 110, pl. 31, figs. 16–18.

1932 Thermalites thermarum; Smith, p. 111, pl. 21, figs. 11–20.

? 1962 Juvenites thermarum; Kummel and Steele, p. 689, pl. 100, figs. 12, 13.

? 1973 Arnautoceltites thermarum; Collignon, p.17, pl. 4, fig. 10.

v 2007 Paranannites sp. indet.; Klug et al., p. 1467, text-fig. 4A–E.

2010 Juvenites septentrionalis; Stephen et al., fig. 5k-, l.

2012a Juvenites cf. thermarum; Brühwiler et al., p. 40, pl. 22, figs. 1–9.

Occurrence Present but not abundant in the Confusion Range [n = 7; DH1-12, DH1-10/11], Pahvant Range [n = 3; DV1-9, DV1-8] and Torrey area [n = 2; FFA1], Owenites beds, Inyoites oweni beds. Not documented from other studied sections.

Description Globose and involute shell with a slightly evolute coiling. Venter rounded. Umbilicus relatively deep with perpendicular wall and broadly rounded shoulders. Ornamentation consists of distant, forward projected constrictions that cross the venter in varying strength. Suture line ceratitic and very simple with two broad, asymmetrical saddles.

Measurements See Figs. 25 and 26. Estimated maximal size: ~4 cm.

Fig. 25
figure25

Scatter diagrams of H, W and U, and H/D, W/D and U/D for Juvenites cf. thermarum (open symbols indicate specimens from the Confusion Range and Pahvant Range, Owenites beds, Inyoites oweni horizons [n = 9]; grey symbols indicate specimens from Oman; data from Brühwiler et al. 2012a [n = 20])

Fig. 26
figure26

Box plots of H/D, W/D and U/D for Juvenites sinuosus from the Caucasus (Shevyrev 1995), J. dieneri from the State of Washington (USA; Kuenzi 1965), J. septentrionalis from Nevada (Kummel and Steele 1962) and J. thermarum from Oman and Utah (Brühwiler et al. 2012a and this work, respectively)

Discussion Species included within Juvenites are often extremely hard to distinguish, especially at small juvenile sizes. Moreover, these taxa also display a wide range of intraspecific variation and consequently, their species diagnoses sometimes overlap. Pending a thorough revision of Juvenites species based on the robust statistics of coiling geometry of a sufficient number of specimens, we follow here the species definition of Smith (1932) and the rare measurements published by, e.g., Kummel and Steele (1962) for American species.

J. cf. thermarum differs from the type species and J. septentrionalis (Smith, 1927) by its more involute coiling and more depressed whorl section (Fig. 26). A comparison with measurements published by Brühwiler et al. (2012a) for J. cf. thermarum yield rather similar results, but the American specimens are probably slightly more depressed. The relatively few measurements of Kummel and Steele (1962) for J. thermarum are more disparate with more extreme variants preventing a strict a comparison of the three collections.

Juvenites spathi (Frebold 1930) and J. procurvus Brayard and Bucher (2008) differ respectively from other species included in the genus by a triangular venter and much stronger, more closely spaced constrictions (see Brayard and Bucher 2008 and Brühwiler et al. 2012a).

J. sinuosus Shevyrev (1995) documented from the Caucasus displays a depressed conch similar to J. thermarum, but its coiling involution is closer to J. septentrionalis (Fig. 26).

Based on their more or less depressed coiling and their involution, J. dieneri (Hyatt and Smith 1905) may be conspecific with J. thermarum (Fig. 26), and J. sanctorum Smith (1932) with J. septentrionalis. This partly agrees with the discussion of Kummel and Steele (1962) regarding the distinction of American Juvenites species. However, without additional measurements from the original material, this hypothesis must remain uncorroborated.

Juvenites aff. spathi (Frebold, 1930)

Fig. 27a–c

Fig. 27
figure27

ac Juvenites aff. spathi (Frebold 1930), UBGD 275029, Loc. FFA1, Torrey area, Owenites beds, below the Inyoites oweni horizons, Smithian. do Vercherites undulatus sp. nov. All from loc. MIA1, Mineral Mountains, Vercherites undulatus sp. nov. beds, Smithian; d UBGD 275030, paratype; eg UBGD 275031, holotype; h scale bar is 5 mm (H = 14.6 mm); i, j UBGD 275032, paratype; km UBGD 275033, paratype; n UBGD 275034, paratype; o suture line of UBGD 275035, paratype, scale bar is 5 mm (H = 13.3 mm)

1930 Prosphingites spathi; Frebold, p. 20, pl. 4, figs. 2, 3, 3a.

1934 Prosphingites spathi; Spath, p. 195, pl. 13, figs. 1, 2.

p? 1959 Prosphingites kwangsianus; Chao, p. 296, pl. 28, figs. 17, 18.

p? 1959 Prosphingites sinensis; Chao, p. 297, pl. 27, figs. 14–17, text-fig. 40a.

? 1961 Prosphingites spathi; Tozer, p. 58, pl. 13, figs. 1, 2.

? 1982 Prosphingites spathi; Korchinskaya, pl. 5, fig. 2.

? 1994 Paranannites spathi; Tozer, p. 77, pl. 36, figs. 1, 2.

v. 2008 Paranannites spathi; Brayard and Bucher, p. 63, pl. 35, figs. 10–19.

v. 2010b Paranannites spathi; Brühwiler et al., p. 426, fig. 16(1, 2).

v. 2012a Juvenites spathi; Brühwiler and Bucher, p. 38, pl. 22, figs. 12–17.

v. 2012b Juvenites cf. spathi; Brühwiler et al., p. 161, figs. 37A–O.

Occurrence Present within the Torrey area [n = 8; only 3 measurable], Owenites beds, below the Inyoites oweni beds. Not documented from other studied sections.

Description Globose and moderately evolute shell with an arched venter. Flanks gradually converge to venter from abruptly rounded umbilical shoulder. Deep, funnel-like umbilicus with high, perpendicular wall and broadly rounded shoulders. Ornamentation barely visible but consists of very weak, dense, forward projected folds (constrictions?) that are more evident on umbilical margins of largest specimens. Suture line ceratitic, with two main, broad saddles, but too poorly preserved to be illustrated.

Measurements See Figs. 28 and 29. Estimated maximal size: ~3 cm (Utah specimens).

Fig. 28
figure28

Scatter diagrams of H, W and U, and H/D, W/D and U/D for Juvenites aff. spathi (open symbols indicate specimens from the Torrey area, base of the Owenites beds, below Churkites and Guodunites occurrences [n = 3]; grey symbols indicate specimens from South China and Oman; data respectively from Brayard and Bucher 2008 and Brühwiler et al. 2012a [n = 82])

Fig. 29
figure29

Box plots of H/D, W/D and U/D for Juvenites aff. spathi from Utah (this work), J. spathi from South China (Brayard and Bucher 2008) and Oman (Brühwiler et al. 2012a) and the morphologically close taxon“Prosphingites” slossi from Nevada (Kummel and Steele 1962)

Discussion Typical large-size specimens of Juvenites (Paranannites) spathi display a triangular whorl section and a marked crateriform umbilicus (see Frebold 1930 and discussion in Brayard and Bucher 2008). However, Korchinskaya (1982), Brühwiler et al. (2010b, 2012b) and Tozer (1994) illustrated more compressed variants with only an arched venter and attribute them to the species. Our specimens from the Torrey area also exhibit a large rounded venter but the coiling is very similar to the species features, especially the funnel-like umbilicus. Although the ornamentation is not well visible compared to other known specimens, which is probably due to their poor preservation, we tentatively assign our specimens to J. spathi. Specimens from Oman (Brühwiler et al. 2012a) also appear slightly more involute than South Chinese specimens (Brayard and Bucher 2008) (Fig. 29).

Kummel and Steele (1962) defined a “Prosphingitesslossi species (Prosphingites is normally considered as a Spathian taxon) displaying at first sight characteristics close to J. spathi, the main difference apparently being a slightly more evolute and compressed coiling (Fig. 29).

Juvenites spathi is found worldwide near the base of the Owenites beds (e.g., Brayardites compressus and Nammalites pilatoides beds in Spiti; Brühwiler et al. 2012b), which is apparently the same for Utah (below occurrence of Churkites and Guodunites).

Family Galfettitidae Brühwiler and Bucher in Brühwiler et al. 2012a

Genus Vercherites Brühwiler et al. 2010c

Type species Koninckites vercherei Waagen, 1895

Vercherites undulatus sp. nov.

Fig. 27d–o

Holotype UBGD 275031 (Fig. 27e–h), loc. MIA1, Mineral Mountains, Vercherites undulatus sp. nov. beds, Smithian.

Derivation of name Species name refers to its folded ornamentation.

Diagnosis Moderately involute Vercherites species, similar to V. pulchrum, but with a simplified auxiliary series in the suture line and exhibiting weak folds on flanks.

Occurrence Abundant in the Mineral Mountains within the Vercherites undulatus sp. nov. beds [MIA1].

Description Moderately involute, compressed shell with an almost triangular whorl section. Inner whorls are tightly coiled and umbilicus gradually opens during ontogeny. Venter tabulate with nearly angular shoulders. Flanks convex with maximum curvature at mid-flank. Umbilicus moderately deep with a high vertical wall and rounded margins. Ornamentation consists of regularly spaced, weak sinuous folds. Surface apparently smoother at small size. Suture line ceratitic with broad second and third lateral saddles and finely indented lobes. A very small auxiliary series is present.

Measurements See Fig. 30. Estimated maximal size: ~7 cm.

Fig. 30
figure30

Scatter diagrams of H, W and U, and H/D, W/D and U/D for Vercherites undulatus sp. nov. (all specimens from Mineral Mountains, Vercherites undulatus bed)

Discussion Our specimens show strong similarities with V. pulchrum from the North Indian Margin (Brühwiler et al. 2010c, 2012c) such as the involute coiling at the juvenile stages. However, they mainly differ by their weak folds on flanks, thus justifying the erection of a new species. Moreover, the auxiliary series of the suture line appears very simplified (rest of suture line is rather similar). It differs from the type species by its more involute coiling. Vercherites vercherei and V. pulchrum also ostensibly reached much larger sizes (>10 cm; e.g., Brühwiler et al. 2012c).

In comparison with ammonoid assemblages from the North Indian Margin (e.g., Brühwiler et al. 2012c), the occurrence of V. undulatus sp. nov. probably represents the oldest Smithian ammonoid fauna found in Utah.

Family Gyronitidae Waagen, 1895

Genus Radioceras Waterhouse, 1996

Type species Meekoceras radiosum Waagen, 1895

Radioceras aff. evolvens (Waagen, 1895)

Fig. 31a–k

Fig. 31
figure31

ak Radioceras aff. evolvens (Waagen 1895). All from loc. DV2-202, Pahvant Range, Radioceras aff. evolvens beds, Smithian. a, b UBGD 275036; ce UBGD 275037; e scale bar is 5 mm (H = 40 mm); fh UBGD 275038; ik UBGD 275039

1895 Aspidites evolvens; Waagen, p. 223, pl. 25, figs. 1.

1895 Aspidites discus; Waagen, p. 228, pl. 25, figs. 2.

1895 Meekoceras radiosum; Waagen, p. 257, pl. 36, fig. 2a–d.

2012c Radioceras evolvens; Brühwiler and Bucher, p. 51, figs. 30A–G, 31A–P.

Occurrence Common in the Pahvant Range, within the Radioceras aff. evolvens beds [DV2-202]. Not found in other studied sections.

Description Involute and compressed shell exhibiting convex, convergent flanks. Venter is tabulate with angular shoulders at small size. Ventral margins and venter become more subtabulate to rounded at large size. Umbilicus rarely preserved and often crushed on our specimens but appears very narrow with rounded shoulders. Surface apparently smooth. Suture line typical with deeply indented lobes and a well-individualized auxiliary series. Second lateral saddle slightly elongated toward the umbilicus.

Measurements Not possible. Estimated maximum size: ~15 cm.

Discussion The overall shape of our specimens and their suture lines closely resemble Radioceras evolvens from the Salt Range (see Brühwiler et al. 2012c). However, since most of our specimens consist of crushed fragments with imperfect preservation, a definitive assignment to R. evolvens is not possible. R. evolvens is very similar to R. kraffti, but apparently differs by its more egressive coiling and a well-individualized auxiliary series (Brühwiler et al. 2012c). R. aff. evolvens represents one of the oldest Smithian ammonoid assemblage found in Utah and by correlation with time-equivalent beds from the North Indian Margin (Brühwiler et al. 2010a, 2012c), it is likely representative of the late early Smithian (Fig. 14).

Family Proptychitidae Waagen, 1895

Genus Guodunites Brayard and Bucher, 2008

Type species Guodunites monneti Brayard and Bucher, 2008

Guodunites hooveri (Hyatt and Smith, 1905)

See Brayard et al. (2009a) for thoroughly illustrated specimens from the Confusion Range

1905 Aspidites hooveri; Hyatt and Smith, p. 153, pl. 17, figs. 1–12.

1932 Clypeoceras hooveri; Smith, p. 63, pl. 17, figs. 1–12.

v 2009a Guodunites hooveri; Brayard et al., p. 476, pl. 2, figs. 1–30.

v 2010 ?Clypeoceras hooveri; Stephen et al., figs. 6e, f, i.

Occurrence Common in Confusion Range [DH1-12, DH1-10/11, DH1-9], Pahvant Range [DV1-9, DV1-8, DV2-7, DV2-6], Mineral Mountains [MIA9, MIA8] and rare in the Torrey area [FF78-83]. Always found within the Owenites beds. Also within the Meekoceras beds, Owenites subzone, Union Wash (Inyo Range, California, USA).

Description For a thorough description with illustrations, reader should refer to Brayard et al. (2009a). Taxon’s main characteristics are (a) involute, platycone shell with a narrowly rounded venter, (b) slightly convex flanks with maximum thickness near mid-flanks, (c) egressive coiling at submature stage, (d) a deep, crateriform umbilicus, (e) projected lirae on outer shell.

On inner whorls, bundled lirae may impart weak folds on flanks. Well-preserved specimens are ornamented with a very delicate strigation (see Brayard et al. 2009a). Suture line subammonitic with delicately crenulated saddles. The architecture of the suture line is similar among species belonging to this genus, especially to that of Guodunites monneti from Guangxi, South China (see Brayard et al. 2009a).

Measurements See Fig. 32. Brayard et al. (2009a) estimated its maximum size to be ~20 cm. However, a maximal size about 15 cm is probably more correct.

Fig. 32
figure32

Scatter diagrams of H, W and U, and H/D, W/D and U/D for Guodunites hooveri (all specimens from the Confusion Range and Pahvant Range, Owenites beds, Inyoites oweni horizon)

Discussion Guodunites hooveri is distinguished from G. monneti from South China by its deeper umbilicus and its more involute coiling. Strong projected lirae are also visible for all ontogenic stages. In contrast with its occurrence at the relatively close Crittenden Springs (Nevada) location, G. monneti appears to not occur in Utah. As previously discussed by Brayard et al. (2009a), this genus is restricted to the late middle Smithian, and to date, its biogeographical distribution comprises only Oman, South China, Nevada, Utah and California thus indicating an essentially low paleolatitudinal distribution. Moreover, its paleobiogeographical distribution further strengthens the existence of significant equatorial faunal exchanges by oceanic currents between both sides of the Panthalassa at that time (Brayard et al. 2006, 2007b, 2009b; Jenks 2007; Jenks et al. 2010).

Genus Wailiceras Brayard and Bucher, 2008

Type species Wailiceras aemulus Brayard and Bucher, 2008.

Wailiceras cf. aemulus

Fig. 33a–e

Fig. 33
figure33

ae Wailiceras cf. aemulus Brayard and Bucher 2008. All from loc. DH1-5, Confusion Range, Inyoites beaverensis sp. nov. beds, Smithian. ac UBGD 275040; c scale bar is 5 mm (H = 23.9 mm); d, e UBGD 275041

Occurrence Very rare. Two specimens found in the Confusion Range within the Inyoites beaverensis sp. nov. beds [DH1-5].

Description Involute and discoidal shell with a tabulate venter and egressive coiling. Ventral shoulders are angular. Flanks are slightly convex with maximum curvature near mid-flank. Umbilical wall rather high and perpendicular with abruptly rounded shoulders. Ornamentation consists of very weak radial plications on outer whorls of one specimen. Suture line with elongated saddles and a small auxiliary series. First lateral saddle rather large.

Measurements See Fig. 34. Estimated maximum size: ~8 cm.

Fig. 34
figure34

Scatter diagrams of H, W and U, and H/D, W/D and U/D for Wailiceras cf. aemulus. Measured specimens from the Confusion Range are indicated by white symbols (Inyoites beaverensis sp. nov. beds). Other data in grey are from South China (“Kashmirites kapila beds” [n = 11]; Brayard and Bucher 2008)

Discussion Brayard and Bucher (2008) thoroughly discussed and illustrated Wailiceras aemulus from South China. This taxon closely resembles poorly preserved specimens of Meekoceras species. W. aemulus mainly differs by its more involute coiling, its vertical umbilical wall and its suture line displaying more elongated saddles and an auxiliary series. Weak plications resembling ornamentation of W. aemulus are visible on one specimen, thus also suggesting strong affinities with specimens from South China. However, due to the poor overall preservation and the restricted number of specimens, a definite assignment to the type species is precluded at this time. The occurrence of W. cf. aemulus in Utah is younger than in South China (“Kashmirites kapila beds”; Brayard and Bucher 2008).

Genus Xiaoqiaoceras Brayard and Bucher, 2008

Type species Xiaoqiaoceras involutus Brayard and Bucher, 2008

?Xiaoqiaoceras americanum sp. nov.

Fig. 35a–c

Fig. 35
figure35

ac ?Xiaoqiaoceras americanum sp. nov., UBGD 275042, holotype, loc. DH1-11, Confusion Range, Owenites beds, Inyoites oweni horizons, Smithian; c scale bar is 5 mm (H = 9.8 mm)

Holotype UBGD 275042 (Fig. 35a–c), loc. DH1-11, Confusion Range, Owenites beds, Inyoites oweni horizons, Smithian.

Derivation of name Species name refers to its American occurrence.

Diagnosis Small moderately involute proptychitid with a characteristic suture line, but differing from the type species by a more compressed whorl section and an almost vertical umbilical wall.

Occurrence Extremely rare. One specimen found in the Confusion Range within the Owenites beds, Inyoites oweni horizons [DH1-11].

Description Moderately involute and relatively laterally compressed shell with a rounded venter. Ventral shoulders are rounded and flanks are almost parallel. Umbilical wall almost vertical with narrowly rounded shoulders. No ornamentation displayed on our unique specimen. Simplified suture line exhibiting a structure similar to Xiaoqiaoceras involutus with a characteristic broad, deep and trifid lateral lobe, and an auxiliary series with numerous small saddles gently bending toward the umbilicus.

Measurements See Table 1. Estimated maximum size: ~3 cm.

Discussion Xiaoqiaoceras is a small peculiar proptychitid distinguished by its unique suture line architecture with a trifid broad and deep lateral lobe. This genus is documented from South China (Brayard and Bucher 2008) and Spiti (Brühwiler et al. 2012b) from older Smithian beds (Flemingites rursiradiatus and Brayardites compressus beds, respectively). Moreover, its attribution to proptychitids is still uncertain (see Brayard and Bucher 2008). Our specimen displays coiling features (also a laterally compressed section and a vertical umbilical wall) that differ greatly from the type species, thus possibly justifying the erection of a new genus and species. However, since our single specimen is only partly preserved and displays a suture line architecture similar to the type species we prefer here to only erect a new species. The genus assignment remains to be confirmed.

Family Dieneroceratidae Kummel, 1952

Genus Dieneroceras Spath, 1934

Type species Ophiceras dieneri Hyatt and Smith, 1905

Dieneroceras dieneri (Hyatt and Smith, 1905)

Fig. 36a–s

Fig. 36
figure36

as Dieneroceras dieneri (Hyatt and Smith 1905). All from the Owenites beds, Inyoites oweni horizons, Smithian; a, b UBGD 275043, loc. DH1-11, Confusion Range; c, d UBGD 275044, loc. DH1-11, Confusion Range; e, f UBGD 275045, loc. DH1-11, Confusion Range; g UBGD 275046, loc. DH1-11, Confusion Range; hk UBGD 275047, loc. DH1-11, Confusion Range; k scale bar is 5 mm (H = 4.9 mm). l, m UBGD 275048, loc. DV1-8, Pahvant Range. np UBGD 275049, loc. DH1-11, Confusion Range; q, r UBGD 275050, loc. DH1-11, Confusion Range; s suture line of UBGD 275051, loc. DV1-9, Pahvant Range, scale bar is 5 mm (H = 4.5 mm). tz Wyomingites cf. aplanatus (White 1879). All from loc. DH1-5, Confusion Range, Inyoites beaverensis sp. nov.beds, Smithian; t, u UBGD 275052; v, w UBGD 275053; xz specimen from the K.G. Bylund personal collection

1905 Ophiceras dieneri; Hyatt and Smith, p. 118, pl. 8, figs. 16–29.

? 1905 Xenaspsis marcoui; Hyatt and Smith, p. 116, pl. 7, figs. 26–33.

1905 Lecanites knechti; Hyatt and Smith, p. 138, pl. 9, figs. 11–16.

1932 Ophiceras dieneri; Smith, p. 48, pl. 8, figs. 16–29.

? 1932 Xenodiscus (Xenaspsis) marcoui; Smith, p. 47, pl. 7, figs. 26–33.

1932 Lecanites (Paralecanites) knechti; Smith, p. 41, pl. 9, figs. 11-16; pl. 28, figs. 1–7.

1955 Ophiceras iwaiense; Sakagami, p. 135, pl. 1, figs. 1–9.

1955 Ophiceras sp.; Sakagami, p. 136, pl. 1, figs. 10–11.

? 1959 Kariceltites indicus; Jeannet, p. XXX, pl. 7, figs. 10–12; pl. 8, fig. 15.

1960 Dieneroceras iwaiense; Kummel and Sakagami, p. 4, pl. 1, figs. 3–5; pl. 2, figs. 7–9.

? 1961 Dieneroceras dieneri; Kiparisova, p.47, pl. 9, fig. 2.

? 1961 Dieneroceras chaoi; Kiparisova, p.48, pl. 9, figs. 3–6.

? 1961 Dieneroceras caucasicum; Popov, p. 41, pl. 6, fig. 1.

? 1965 Dieneroceras cf. dieneri; Kuenzi, p. 369, pl. 53, figs. 13–18, text-figs. 3, 4.

1968 Dieneroceras dieneri; Nakazawa and Bando, p. 93, pl. 4, figs. 1–6.

1968 Dieneroceras aff. chaoi; Nakazawa and Bando, p. 95, pl. 4, figs. 7, 8; pl. 5, fig. 1.

? v 1973 Dieneroceras knechti; Collignon, p. 131, pl. 1, figs. 2, 3.

? v 1973 Dieneroceras chaoi; Collignon, p. 132, pl. 1, figs. 6–8.

? 1995 Dieneroceras caucasicum; Shevyrev, p. 25, pl. 1, figs. 3–5.

? 1995 Dieneroceras magnum; Shevyrev, p. 26, pl. 1, fig. 6.

2010 Wyomingites arnoldi; Stephen et al, fig. 5c, d.

2012a Dieneroceras dieneri; Brühwiler and Bucher, p. 20, pl. 8, figs. 1–4; pl. 9, figs. 1–7; pl. 10, figs. 1–3.

Occurrence Common in all studied sections within the Owenites beds, Inyoites oweni horizons except the Torrey area, where the taxon was not found [DH1-12, DH1-10/11; DV1-8; MIA9].

Description Evolute, laterally compressed shell with a subtabulate to tabulate venter and a large umbilicus. Coiling very weakly embracing preceding whorls. Broadly convex flanks with maximum thickness near umbilicus forming a slightly ovoid whorl section. Inner whorls slightly more rounded than outer whorls. Body chamber length unknown. Umbilical wall steeply inclined with rounded shoulders forming a shallow umbilicus. Ornamentation smooth with only weak folds; the spiral strigation described by Hyatt and Smith (1905) on the type specimen and on certain other species by other workers was not observed on our specimens. Classical simple ceratitic suture line with deep, but very delicately indented lobes and two main large lateral saddles. Suture line at juvenile stages is goniatitic.

Measurements See Figs. 37 and 38. Estimated maximum size: ~3.5 cm for our specimens.

Fig. 37
figure37

Scatter diagrams of H, W and U, and H/D, W/D and U/D for Dieneroceras dieneri (all specimens from the Confusion Range and Pahvant Range, Owenites beds, Inyoites oweni horizon)

Fig. 38
figure38

Box plots of H/D, W/D and U/D for Dieneroceras dieneri from Utah (this work), D. cf. dieneri from Oman (Brühwiler et al. 2012a), D. tientungense from Guangxi and Spiti (Brayard and Bucher 2008 and Brühwiler et al. 2012b, respectively) and D. spathi from Crittenden Springs, Nevada (J. Jenks, ongoing work)

Discussion Some confusion still remains not only between species included in the genus but also at higher taxonomic level. For a preliminary discussion on this issue, the reader should refer to Brayard and Bucher (2008, p. 40). Among taxa from Crittenden Springs (Nevada) attributed by Kummel and Steele (1962) to Dieneroceras, D. knetchi differs from the type species by a rounded venter and a goniatitic suture line. Generally, the erection of a different species based only on a goniatitic suture line is not supported, especially if the goniatitic aspect results from poor preservation of some juvenile specimens. However, observed specimens from Kummel’s collection and additional specimens from this locality (J. Jenks, personal observation) confirm that their suture lines are goniatitic. Our specimens of D. dieneri often show a goniatic suture line at juvenile stages or when poorly preserved. Thus, we regard D. knetchi as a valid species, but this conclusion is based only on its rounded venter. D. spathi erected by Kummel and Steele (1962) shows a more involute coiling and more noticeable ornamentation.

D. woondumense from Queensland (Australia) displays a coarse radial ribbing on its inner whorls, which is a unique characteristic for this genus (Runnegar 1969). D. iwaiense from Japan was erected only on the absence of a strigation as compared to the type species (Kummel and Sakagami 1960, p. 5). However, American specimens of D. dieneri may or may not display strigation that is only seldom preserved. Thus, the absence of strigation is not useful to discriminate Dieneroceras species and we assign the Japanese species to D. dieneri. D. cf. dieneri illustrated by Kuenzi (1965) from the State of Washington (USA) appears very similar to our specimens and probably belongs to the type species. Dieneroceras caucasicum and D. magnum fall within the intraspecific variation of the type species, but their radial folding may be more obvious (e.g., Shevyrev 1995).

D. marcoui (Hyatt and Smith 1905) may also be synonymized with the type species. However, one illustrated specimen (Hyatt and Smith 1905 and Smith 1932, pl. 7, fig. 26) displays distinct radial folds that do not correspond with the diagnosis of the type species.

Dieneroceras knechti and D. chaoi described from Afghanistan by Collignon (1973) are fragmentary specimens and casts that impede a definitive assignment to the type species. However, the geometrical and morphological characteristics of the Afghan samples are extremely similar to D. dieneri.

Note that most Dieneroceras species discussed up till now co-occur with the middle Smithian time-marker Owenites.

D. tientungense from Guangxi (South China; Brayard and Bucher 2008) and D. cf. tientungense from Spiti (Brühwiler et al. 2012b) mainly differ from the type species by exhibiting a high variation in whorl section, a more perpendicular umbilical wall, strigation near the venter and weak constrictions on some large specimens. The H/D, W/D and U/D ratios between these species and D. dieneri are rather similar (Fig. 38) although the maximum size of American specimens is apparently much smaller. D. tientungense apparently also occurs earlier than the type species in Guangxi and Spiti (Flemingites beds; Brayard and Bucher 2008; Brühwiler et al. 2012b).

Genus Wyomingites Hyatt in Zittel, 1900

Type species Meekoceras aplanatum White, 1879

Wyomingites cf. aplanatus (White, 1879)

Fig. 36t–z

1879 Meekoceras aplanatum; White, p. 112.

1880 Meekoceras aplanatus; White, p. 112, pl. 31, fig. 1a, b, d.

1900 Wyomingites aplanatus; Hyatt, p. 556.

1902 Ophiceras aplanatum; Frech, p. 631.

1905 Meekoceras (Gyronites) aplanatum; Hyatt and Smith, p. 146, pl. 11, figs: 1-14; pl. 64, figs. 17–22; pl. 77, figs. 1-2.

1932 Flemingites aplanatus; Smith, p. 51, pl. 11, figs. 1–14; pl. 22, figs. 1–23; pl. 39, figs. 1, 2; pl. 64, figs. 17–32.

? 1959 Wyomingites cf. aplanatus; Kummel, p. 444, figs. 5, 6.

1962 Wyomingites cf. aplanatus; Kummel and Steele, p. 696, pl. 99, figs. 3, 4.

? 1979 Wyomingites aplanatus; Nichols and Silberling, pl. 1, figs. 19–21.

2008 Wyomingites aplanatus; Brayard and Bucher, p.42, pl. 16, figs. 1–3.

2010 Wyomingites aplanatus; Stephen et al., fig. 4c–e.

Occurrence Rare in the Confusion Range [DH1–5, DH1–4], Inyoites beaverensis sp. nov. beds. Not documented from other studied sections.

Description Evolute and laterally compressed shell with a subrectangular whorl section, a tabulate venter, rounded ventral shoulders, and nearly parallel flanks. Umbilicus with low, perpendicular wall and rounded shoulders. Typical strigation not visible on our poorly preserved specimens. Variable and wavy ribs visible. Suture line ceratitic, simple and structurally similar to Dieneroceras.

Measurements See Table 1. Estimated maximum size up to: ~5 cm.

Discussion See Brayard and Bucher (2008) for a discussion of the genus attribution to Dieneroceratidae. Although showing a similar overall morphology to W. aplanatus, our poorly preserved specimens do not display the typical strigation of this species, thus preventing a firm assignment to the type species. The occurrence of W. aplanatus in South China may be older (Flemingites rursiradiatus beds; Brayard and Bucher 2008) than in Utah.

Family Flemingitidae Hyatt in Zittel, 1900

Genus Flemingites Spath, 1934

Type species Ceratites flemingianus de Koninck, 1863

Flemingites sp. indet.

Fig. 39a–d

Fig. 39
figure39

ad Flemingites sp. indet. UBGD 275054, loc. DV2-5, Pahvant Range, Flemingites sp. indet. beds, Smithian; d scale bar is 5 mm (H = 24 mm)

Occurrence Very rare, one specimen was found in the Pahvant Range (Flemingites sp. indet. bed, DV2-5). Not found in other studied sections.

Description Moderately evolute and laterally compressed shell with a narrowly arched venter and rounded ventral shoulders. Flanks parallel near umbilicus, then gradually converge to the venter. Umbilicus wide with a deep, inclined wall and rounded margins. Ornamentation consists of a delicate, barely perceptible strigation and variable weak folds on flanks. Suture line ceratitic with rounded, deep lateral saddles and large indented lobes.

Measurements See Table 1. Estimated maximum size: ~10 cm.

Discussion Our single specimen displays the main diagnostic characters of Flemingites species: strigation, folds and a well-developed suture line with rounded saddle. However, its poor preservation precludes a definite assignment to a Flemingites species. Surprisingly, flemingitids are much rarer in Utah than in some other known Smithian localities in the USA, such as Crittenden Springs and southeast Idaho (Nevada: e.g., Kummel and Steele 1962; Jenks et al. 2010; southeast Idaho: e.g., Smith 1932). Their rarity in Utah remains enigmatic.

Genus Anaflemingites Kummel and Steele, 1962

Type species Anaflemingites silberlingi Kummel and Steele, 1962

Anaflemingites aff. silberlingi

Fig. 40a–c

Fig. 40
figure40

ac Anaflemingites aff. silberlingi Kummel and Steele 1962. UBGD 275055, loc. DV1-7, Pahvant Range, Owenites beds, Smithian; c scale bar is 5 mm (H = 7.2 mm)

2000 Anaflemingites silberlingi; Kummel and Steele, pl. 667, pl. 102, fig. 10.

v 2010 Anaflemingites silberlingi; Jenks et al., p. 23, figs 14, 16–18.

Occurrence Rarely occurs in the Confusion Range at the base of the Owenites beds (DH1-8). Also rare in the Pahvant Range, within the Owenites beds (DV1-7) and possibly within the Inyoites beaverensis sp. nov. beds (DV2-4). Not found in other studied sections.

Description Moderately evolute and laterally compressed, discoidal shell with a well-rounded venter. Flanks slightly convex with maximum curvature near mid-flank, converging to the venter without distinct ventral shoulders. Umbilicus relatively shallow with a gently sloped wall and rounded margins. Our specimens display biconcave ribs, folds and growth lines. Ribs appear more noticeable at small size. Suture line ceratitic with a broad, deep and well-indented first lateral saddle.

Measurements See Fig. 41. Estimated maximal size: ~15 cm.

Fig. 41
figure41

Scatter diagrams of H, W and U, and H/D, W/D and U/D for Anaflemingites aff. silberlingi from Utah (white symbols; two specimens from the Confusion Range, base of the Owenites beds) and Anaflemingites silberlingi from Nevada (grey symbols; data from Jenks et al. 2010 [n = 20, Meekoceras gracilitatis Zone])

Discussion Jenks et al. (2010) provided a thorough revision of the genus, based on numerous specimens from Crittenden Springs, Nevada. Our specimens are somewhat similar to the type species. However, they are small-sized and do not display the characteristic strigation, thus preventing their attribution to A. silberlingi. In addition, the venters of the Crittenden Springs specimens are more narrowly rounded. Moreover, the suture line of our specimens exhibits a first lateral saddle that is broader than specimens from Nevada.

Family Arctoceratidae Arthaber, 1911

Genus Churkites Okuneva, 1990

Type species Churkites egregius Zharnikova and Okuneva in Okuneva 1990

Churkites noblei Jenks, 2007

Figs. 42a–f and 43a–d

Fig. 42
figure42

af Churkites noblei Jenks 2007. All from the Owenites beds, Smithian; ab UBGD 275056, loc. DV1-7, Pahvant Range; cd specimen from the K.G. Bylund personal collection, loc. DH1-12, Confusion Range; ef UBGD 275057, loc. DH1-12, Confusion Range

Fig. 43
figure43

Churkites noblei Jenks 2007. All from the Owenites beds, Smithian; a UBGD 275058, loc. DH1-12, Confusion Range (maximum diameter of this specimen is ~340 mm); bd UBGD 275059, loc. DV1-9, Pahvant Range; b scale bar is 5 mm (H = 13.5 mm)

2000 Arctoceras sp.; Gardner and Mapes, pl. 2, fig. 1.

v 2007 Churkites noblei; Jenks, p. 83, figs. 2, 4, 7–9.

v 2010 Churkites noblei; Stephen et al., figs. 5i, j.

Occurrence Common in the Confusion Range [DH1-12, DH1-10/11, DH1-9; DV1-9, DV1-8, DV2-7; MIA9] and Pahvant Range, occurs in the Mineral Mountains and rare in the Torrey area. Rare within the uppermost portion of the Gracilitatis Zone at Crittenden Springs, Nevada (Jenks 2007; Jenks et al. 2010). Always found within the Owenites beds of the studied sections.

Description Very large sized Arctoceratid with a diagnostic narrowly rounded venter on juveniles that becomes distinctively acute or angular on mature whorls. Coiling moderately evolute with compressed and relatively high whorls. Flanks gently convex forming a somewhat ovoid whorl (see Jenks 2007 for thorough description). Umbilicus wide with moderately high, inclined wall and abruptly rounded shoulders. Umbilical wall quite steep on early whorls, but gradually becoming more inclined throughout ontogeny. Ornamentation consists of weak to strong tuberculations on umbilical shoulders becoming denser and more bullate and ridge-like on adult whorls. Some slightly sinuous fold-like ribs are visible, but vary greatly in strength, width and frequency. Ribs rapidly fade away on ventral shoulders. Well-preserved shells (see specimens from Crittenden Springs; Jenks 2007) exhibit very fine, narrow, and dense radial lirae.

Suture line ceratitic, consisting of well-denticulated ventral, first lateral and second lateral lobes, as well as short auxiliary series. Width of lobes gradually decreases towards umbilicus. First lateral saddle wide and well-rounded, while second lateral saddle is somewhat narrower, but still well-rounded.

Measurements See Fig. 44. Estimated maximum size up to: ~40 cm.

Fig. 44
figure44

Scatter diagrams of H, W and U, and H/D, W/D and U/D for Churkites noblei. Measured specimens from the Confusion Range and Pahvant Range (Owenites beds, Inyoites oweni horizons) and from Crittenden Springs, Nevada (Jenks 2007)

Discussion Two species of Churkites were originally erected from the Anasibirites nevolini Zone of South Primorye: C. egregius (Zharnikova and Okuneva in Okuneva 1990) and C. syaskoi (Zakharov and Shigeta in Markevich and Zakharov 2004). C. noblei is very similar to these Russian species, but it essentially differs by its more ovoid section, more inclined umbilical wall and less dense ribs (Jenks 2007). The suture line of C. syaskoi also appears to be somewhat different with more denticulated lobes and more complex auxiliary series (Jenks 2007). Jenks (2007) suggested that C. noblei, which occurs only in the latest middle Smithian beds just below the Anasibirites kingianus beds, is slightly older than the Russian Churkites species both of which occur in the late Smithian Anasibirites nevolini Zone. However, since the distribution of ammonoid taxa within the A. nevolini Zone (and thus its definition) is still not clear, all Churkites species may have temporally co-existed.

The morphology, ornamentation and suture line of C. noblei are closer to Arctoceras tuberculatum than to the Russian Churkites species (Jenks 2007). Consequently, it can be somewhat difficult to differentiate between juvenile and adolescent specimens of C. noblei and A. tuberculatum, especially if the particular A. tuberculatum specimen happens to be one of the more compressed variants. Fortunately, the whorl section of most A. tuberculatum shells tends to be subquadrate.

The close affinities of Churkites species between opposite sides of Panthalassa again underline the potential long-distance faunal exchange that occurred during the Early Triassic.

Genus Arctoceras Hyatt in Zittel, 1900

Type species Ceratites polaris Mojsisovics, 1896

Arctoceras tuberculatum (Smith, 1932)

Fig. 45a–c

Fig. 45
figure45

ac Arctoceras tuberculatum (Smith 1932). UBGD 275060, loc. DV2-2, Pahvant Range, Preflorianites–Kashmirites beds, Smithian; c scale bar is 5 mm (H = 48.5 mm)

1932 Meekoceras tuberculatum; Smith, p. 62, pl. 50, fig. 1–4.

1962 Arctoceras tuberculatum; Kummel and Steele, p. 697, pl. 104, figs. 1–8.

1979 Arctoceras tuberculatum; Nichols and Silberling, pl. 1, figs. 5–9.

? 1994 Arctoceras gigas; Tozer, p. 65, pl. 26, figs. 4–6.

v. 2010 Arctoceras tuberculatum; Jenks et al., internal frontspiece.

Occurrence Rare. A few large fragmentary specimens found within the Preflorianites–Kashmirites beds of the Confusion Range [DH1-1] and Pahvant Range [DV2-1 to DV2-2]. One large complete specimen found in DV2-2. Not documented from other studied sections. Abundant throughout the Meekoceras gracilitatis Zone, up to the Anasibirites Zone at Crittenden Springs, Nevada (Jenks et al. 2010).

Description Large-sized Arctoceratid with a moderately evolute, compressed shell. Venter varies from narrowly rounded to well-rounded on smaller specimens to well-rounded or broadly rounded on larger specimens. Flanks weakly convex, but whorl section remains subquadrate. Umbilicus rather wide with a high, nearly perpendicular wall and abruptly rounded margins. Characteristic ornamentation consists of conspicuous tubercles on umbilical shoulders often becoming denser on adult whorls. Some large radial, sinuous ribs are also visible, but they vary greatly in strength and width, and become denser at large sizes. Fine strigation is visible on well-preserved specimens from Crittenden Springs (Kummel and Steele 1962; Jenks et al. 2010), but not on our specimens. Suture line ceratitic with broad lobes and an auxiliary series. Width of lobes gradually decreases towards umbilicus.

Measurements See Figs. 46 and 47. Estimated maximum size up to: ~25 cm.

Fig. 46
figure46

Scatter diagrams of H, W and U, and H/D, W/D and U/D for Arctoceras tuberculatum. The single complete measured specimen from the Pahvant Range is indicated by white symbols (Preflorianites–Kashmirites beds). Other data in grey are from Crittenden Springs, Nevada (“Meekoceras gracilitatis zone”; Kummel and Steele 1962)

Fig. 47
figure47

Box plots of H/D, W/D and U/D for Arctoceras tuberculatum from Utah and Nevada (this work and Kummel and Steele 1962, respectively), A. septentrionale from South Primorye (Zakharov 1968) and Churkites noblei from Utah and Nevada (this work and Jenks 2007, respectively)

Discussion Arctoceras blomstrandi (Lindström 1865) from the Canadian Arctic (Tozer 1994) and Spitsbergen (Weitschat and Lehmann 1978) exhibits the same typical umbilical nodes, but appears slightly more involute. A. strigatus from South China (Brayard and Bucher 2008) differs by its conspicuous strigation and its absence of umbilical tuberculation. Arctoceras gigas from the Canadian Arctic (Tozer 1994) probably should be synonymized with A. tuberculatum due to the similar characters they share, but additional specimens of the Canadian taxon are necessary to definitively corroborate this hypothesis. A. schalteggeri from Pakistan (Brühwiler et al. 2011) does not have true umbilical tubercles but only weak ribs thickening at the umbilical margin. A. septentrionale from South Primorye (Zakharov 1968; Shigeta and Zakharov 2009) is rather similar but apparently more involute (Fig. 47). A. subhydapsis, also from South Primorye (e.g., Shigeta and Zakharov 2009), is described as more evolute than A. tuberculatum. Additional specimens and measurements from this Russian taxon are needed to statistically confirm the erection of a different species.

As previously discussed, Churkites noblei and A. tuberculatum are sometimes difficult to differentiate when the studied specimens are juvenile and adolescent. The adult stage of C. noblei can be easily distinguished by its angular venter, and it also appears to be slightly more compressed (Fig. 47). A. tuberculatum has definitively been documented here only from beds underlying the Owenites beds, but it may range up to the Anasibirites kingianus beds in other parts of the basin (e.g., Crittenden Springs; Jenks et al. 2010).

Genus Submeekoceras Spath, 1934

Type species Meekoceras mushbachanum White, 1879

Submeekoceras mushbachanum (White, 1879)

Fig. 48a, b

Fig. 48
figure48

a, b Submeekoceras mushbachanum (White 1879). Specimen from the K.G. Bylund personal collection, loc. DH1-4, Confusion Range, Inyoites beaverensis sp. nov. beds, Smithian. ch Minersvillites farai gen. nov., sp. nov. All from loc. MIA4, Mineral Mountains, base of the Owenites beds, Smithian; c UBGD 275061, paratype; d, e UBGD 275062, paratype; f Group of Minersvillites farai gen. nov., sp. nov., UBGD 275063, paratypes; g, h UBGD 275064, holotype; h scale bar is 5 mm (H = 8.3 mm)

1879 Meekoceras mushbachanum; White, p. 113.

1880 Meekoceras mushbachanum; White, p. 114, pl. 32, fig. 1a–d.

1902 Prionolobus mushbachanum; Frech, p. 631: c.

1904 Meekoceras mushbachanum; Smith, p. 376, pl. 41, figs. 1–3; pl. 43, figs. 1, 2.

1905 Meekoceras (Koninckites) mushbachanum; Hyatt and Smith, p. 149, pl. 15, figs. 1–9; pl. 16, figs. 1–3; pl. 18, figs. 1–7; pl. 70, figs. 8–10.

1914 Meekoceras mushbachanum; Smith, p. 77, pl. 72, figs. 1, 2; pl. 73, figs. 1–6; pl. 74, figs. 1–23.

1915 Meekoceras mushbachanum; Diener, p. 193.

non 1922 Meekoceras mushbachanum; Welter, p. 126.

1932 Meekoceras (Koninckites) mushbachanum; Smith, p. 61, pl. 15, figs. 1–9; pl. 16, figs. 1–3; pl. 18, figs. 1–7; pl. 38, figs. 1; pl. 59, figs. 17–21; pl. 70, figs. 8–10; pl. 74, figs. 1–23; pl. 75, figs. 1–6; pl. 76, figs. 1–3.

1932 Meekoceras (Koninckites) mushbachanum var. corrugatum; Smith, p. 61, pl. 38, fig. 1.

1932 Meekoceras (Koninckites) evansi; Smith, p. 60, pl. 35, figs. 1–3; pl. 36, figs. 1–18.

1934 Submeekoceras mushbachanum; Spath, p. 255, fig. 87.

v 1959 Paranorites ovalis; Chao, p. 217, pl. 9, figs. 16-19, text-fig. 16b.

? 1959 Prionolobus ophionus var. involutus; Chao, p. 201, pl. 9, figs. 11–15, text-fig. 11b.

v 1959 Prionolobus hsuyuchieni; Chao, p. 202, pl. 9, figs. 9-10, text-fig. 11c.

? 1959 Meekoceras (Submeekoceras) tientungense; Chao, p. 317, pl. 14, figs. 6, 7, textfig. 45b.

v 1959 Meekoceras (Submeekoceras) subquadratum; Chao, p. 317, pl. 14, figs. 1–5; pl. 39, figs. 8, 9, text-fig. 45c.

v 1959 Meekoceras densistriatum; Chao, p. 310, pl. 38, figs. 1–3, 19, text-fig. 43b.

v 1959 Meekoceras yukiangense; Chao, p. 311, pl. 39, figs. 1–7, text-fig. 44a.

v 1959 Meekoceras kaohwaiense; Chao, p. 311, pl. 40, figs. 16–18, text-fig. 44b.

v 1959 Meekoceras pulchriforme; Chao, p. 313, pl. 40, figs. 14, 15, text-fig. 44c.

? 1959 Meekoceras jolinkense; Chao, p. 314, pl. 14, figs. 12–15.

v 1959 Meekoceras lativentrosum; Chao, p. 309, pl. 38, figs. 15–18, text-fig. 43a.

v 1959 Proptychites latumbilicutus; Chao, p. 234, pl. 19, figs. 2, 3, text-fig. 22a.

? 1959 Proptychites kaoyunlingensis; Chao, p. 234, pl. 16, figs. 7, 8, text-fig. 22b.

p 1968 Arctoceras mushbachanum; Kummel and Erben, p. 131, pl. 21, fig. 1 only.

v 2008 Submeekoceras mushbachanum; Brayard and Bucher, p. 53, pl. 16, fig. 4; pl. 26, figs. 1–9.

2010 Submeekoceras mushbachanum; Stephen et al., figs. 4a, b.

v 2012a Submeekoceras mushbachanum; Brühwiler and Bucher, p. 30, pl. 17, figs. 1–3.

Occurrence Occurs in the Confusion Range [DH1-5, DH1-4] within the Inyoites beaverensis sp. nov. beds, and rarely occurs in the Mineral Mountains [MIA4] at the base of the Owenites beds.

Description Slightly evolute, somewhat compressed platycone with flat, parallel flanks, a venter that varies from narrowly rounded to well-rounded on smaller specimens to well-rounded on larger specimens, with rounded ventral shoulders. Umbilicus rather deep with high, flat, perpendicular wall and abruptly rounded shoulders. Ornamentation consists of sinuous growth lines and weak, but noticeable fold-like ribs similar to Arctoceras. Suture line unknown on our specimens, but it is usually similar to Arctoceras with less indented lateral lobes.

Measurements See Table 1. Estimated maximum size: ~15 cm (see Brayard and Bucher 2008).

Discussion This taxon clearly belongs to the Arctoceratidae and juvenile specimens are hardly distinguishable from Arctoceras or Churkites. It mainly differs from Arctoceras tuberculatum by the absence of umbilical tuberculation.

Genus Minersvillites gen. nov.

Type species Minersvillites farai gen. nov., sp. nov.

Composition of the genus Type species only.

Derivation of name Named after the small town of Minersville located just southwest of the Mineral Mountains section (Utah).

Diagnosis Evolute and compressed arctoceratid with a slightly inclined umbilical wall and sinuous, radial ribs disappearing on outer whorls.

Discussion This taxon exhibits a discoidal shape with almost parallel flanks, an arched venter, prominent ribs, a high umbilical wall and an apparently well-indented suture line with large saddles. Thus, it likely belongs to Arctoceratidae. It can be distinguished from other arctoceratids by its more evolute coiling and slightly inclined umbilical wall. Moreover, it appears to be more laterally compressed with a more ovoid whorl section. Ornamentation closely resembles that of Submeekoceras muschbachanum with sinuous growth lines and radial ribs fading on outer whorls. However, these ribs are more prominent near the umbilical margin, and tend to generate a small longitudinal fold at this location and thus resemble umbilical tubercles of other arctoceratids.

Minersvillites farai gen. nov., sp. nov.

Fig. 48c–h

Holotype UBGD 275064 (Fig. 48g, h), loc. MIA4, Mineral Mountains, base of the Owenites beds, Smithian.

Derivation of name Named after Emmanuel Fara (Dijon).

Diagnosis As for the genus.

Occurrence Rare in the Mineral Mountains at the base of the Owenites beds [MIA4; n = 4]. Not documented from other studied sections.

Description Evolute, laterally compressed arctoceratid with a rather narrowly arched venter. Flanks appear almost parallel near the umbilicus and become convergent towards the venter at 2/3rd of flanks. Umbilicus wide with a slightly oblique, high wall and markedly rounded shoulders. Ornamentation consists of dense, sinuous, radial growth lines and irregularly spaced ribs. Ribs are quite large and their tops sometimes become acute. Ribs fade at a large diameter and only perceptible growth lines remain. Ceratitic suture line only partly known with a broad third lateral saddle, a deeply indented lateral saddle and a short auxiliary series.

Measurements See Table 1. Estimated maximum size: ~10 cm.

Discussion As for the genus.

Family Inyoitidae Spath, 1934

Genus Inyoites Hyatt and Smith, 1905

Type species Inyoites oweni Hyatt and Smith, 1905

Inyoites oweni Hyatt and Smith, 1905

Fig. 49a–t

Fig. 49
figure49

Inyoites oweni Hyatt and Smith 1905. All from the Owenites beds, Inyoites oweni horizons, Smithian; a, b UBGD 275065, loc. DH1-10, Confusion Range; ce UBGD 275066, loc. DH1-12, Confusion Range. f UBGD 275067, loc. DV1-8, Pahvant Range; gi UBGD 275068, loc. DH1-11, Confusion Range; j UBGD 275069, loc. DH1-11, Confusion Range; km UBGD 275070, loc. DV1-9, Pahvant Range; n, o UBGD 275071, loc. DH1-12, Confusion Range; pr UBGD 275072, loc. DH1-12, Confusion Range; s suture line of UBGD 275073, loc. DH1-11, Confusion Range, scale bar is 5 mm (H = 21.5 mm); t UBGD 275074, loc. DV1-9, Pahvant Range

1905 Inyoites oweni; Hyatt and Smith, p. 134, pl. 6, figs. 1-16, pl. 69, figs. 1–9, pl. 78, figs. 1–8.

1932 Inyoites oweni; Smith, p. 80, pl. 6, figs. 1–16, pl. 40, figs. 1–8, pl. 69, figs. 1–9.

1934 Inyoites oweni; Spath, p. 138, fig. 37.

1968 Inyoites spicini; Zakharov, p. 151, pl. 30, fig. 2.

v 1973 Inyoites oweni; Collignon, p. 12, pl. 1, fig. 9.

? 1995 Inyoites oweni; Shevyrev, p. 12, pl. 1, fig. 9.

v 2010 Inyoites oweni; Stephen et al., figs. 5a, b.

2012a Inyoites oweni; Brühwiler and Bucher, p. 34, pl.21, figs. 1–6.

? 2012a Inyoites sp. indet.; Brühwiler and Bucher, p.35, pl.21, fig. 8.

Occurrence Very abundant in the Confusion Range, Pahvant Range and Mineral Mountains within the upper part of the Owenites beds, Inyoites oweni horizons. Often co-occurs with Guodunites hooveri and Churkites noblei. Not documented from the Star Range and the Torrey area. Also found in the Owenites beds of Afghanistan (Collignon 1973), the Caucasus (Shevyrev 1995) and Oman (Brühwiler et al. 2012a).

Description Moderately involute, compressed shell with slightly convex flanks. Lanceolate venter with a characteristic high, pronounced keel. Ventral shoulders barely perceptible, but very gently rounded. Umbilicus shallow with a relatively high wall, becoming distinctively more and more inclined on mature whorls with abruptly rounded shoulders. Ornamentation consists of very conspicuous slightly sinuous fold-like ribs varying greatly in strength and width. Ribs rapidly fade away on outer half of the flanks where they are gradually transformed into very fine, narrow, dense and sinuous lirae. Ribs almost radial or most often slightly rursiradiate. On rare robust specimens, ribs are distinctively rursiradiate. Well-preserved specimens sometimes exhibit a faint strigation. Suture line ceratitic with rather deep lobes. Saddles elongated and rounded.

Measurements See Figs. 50 and 51. Estimated maximum size: ~8 cm.

Fig. 50
figure50

Scatter diagrams of H, W and U, and H/D, W/D and U/D for Inyoites oweni (all specimens from the Confusion Range and Pahvant Range, Owenites beds, Inyoites oweni horizons)

Fig. 51
figure51

Box plots of H/D, W/D and U/D for Inyoites oweni from Utah (this work), Oman (Brühwiler et al. 2012a) and the Caucasus (Shevyrev 1995), I. krystyni from Guangxi (Brayard and Bucher 2008) and I. beaverensis sp. nov. (this work)

Discussion Inyoites krystyni Brayard and Bucher (2008), erected from the Owenites beds, Inyoites horizon of Guangxi (South China), can be distinguished from the type species by its more evolute coiling, its larger maximum size (up to ~15 cm) and its weaker ornamentation. These two species are diagnostic of the upper part of the middle Smithian in the USA and South China, thus facilitating biostratigraphical correlation between each side of Panthalassa. Inyoites sp. indet. described from Oman (Brühwiler et al. 2012a) is probably conspecific with the type species, the main difference being its strong rursiradiate ribs. However, some rare I. oweni specimens from Utah exhibit the same type of ornamentation, and a wide range of rib variation from almost straight to rursiradiate is found. Moreover, the more slightly evolute coiling noted by Brühwiler et al. (2012a) for Inyoites sp. indet. may simply be due to intraspecific variation.

Inyoites oweni also occurs at Crittenden Springs (Nevada), but it is extremely rare (Jenks, ongoing work). I. stokesi described by Kummel and Steele (1962) probably has to be assigned to the genus Subvishnuites (see Brayard and Bucher 2008) due to the apparent absence of a ventral keel.

Inyoites beaverensis sp. nov.

Fig. 52a–p

Fig. 52
figure52

Inyoites beaverensis sp. nov. All from loc. DH1-5, Confusion Range, Inyoites beaverensis sp. nov. beds, Smithian; ab UBGD 275075, paratype; cf UBGD 275076, holotype; f scale bar is 5 mm (H = 9.2 mm); g, h UBGD 275077, paratype; ik UBGD 275078, paratype; ln UBGD 275079, paratype; o, p UBGD 275080, paratype

Holotype UBGD 275076 (Fig. 52c–f), loc. DH1-5, Confusion Range, Inyoites beaverensis sp. nov. beds, Smithian.

Derivation of name Named after the city of Beaver (Utah).

Diagnosis Rather evolute inyoitidae differing from the type species by a more evolute coiling, weaker ornamentation, a less lanceolate venter and a much smaller keel.

Occurrence Abundant in the Confusion Range within the Inyoites beaverensis sp. nov. beds [DH1-5, DH1-4]. Rare in the Pahvant Range [DV2-4, DV2-3e, DV2-3d] and the Mineral Mountains [MIA3, MIA2]. Not documented from other studied sections.

Description Evolute, laterally compressed shell with an acute venter and a small, delicate, rarely preserved keel. Flanks parallel near the umbilicus, rapidly becoming convergent towards the venter. Umbilicus wide with rounded margins and an oblique wall. Our specimens do not display any marked ornamentation except for weak, radial folds at mid-flank. Suture line ceratitic, similar to Inyoites oweni with elongated saddles and deep, finely indented lateral lobes.

Measurements See Fig. 53. Estimated maximum size: ~7 cm.

Fig. 53
figure53

Scatter diagrams of H, W and U, and H/D, W/D and U/D for Inyoites beaverensis sp. nov. (all specimens from the Confusion Range, Inyoites beaverensis sp. nov. beds)

Discussion Inyoites beaverensis sp. nov. differs from the type species by a near-absence of ornamentation and its more evolute coiling. It can also be distinguished from I. krystyni (see Brayard and Bucher 2008) by its less parallel flanks near the venter and its smaller keel. I. krystyni also appears more evolute (Fig. 51). Subvishnuites stokesi described by Kummel and Steele (1962) from Nevada exhibits a rather similar coiling ratio, but apparently does not have a ventral keel. Moreover, S. stokesi is more ornamented. At first sight, I. beaverensis sp. nov. in terms of morphology may be considered to be an “intermediate” form between Inyoites and Subvishnuites species.

Family Lanceolitidae Spath, 1934

Genus Lanceolites Hyatt and Smith, 1905

Type species Lanceolites compactus Hyatt and Smith, 1905

Discussion Lanceolites is an easily distinguishable genus, especially when its suture lines are apparent. Lucas et al. (2007a) reported a specimen of Lanceolites sp. from the San Rafael Swell that supposedly co-occurs with Anasibirites and Wasatchites. Although its overall shape resembles Lanceolites, the lack of an illustrated suture lines prevents a definite assignment to this taxon. If this attribution is confirmed in the future, it will represent the only known worldwide occurrence of this genus within the Anasibirites kingianus beds. Despite intensive sampling efforts in the San Rafael Swell, we failed to find this genus within these late Smithian beds.

Lanceolites compactus Hyatt and Smith, 1905

Fig. 54a–k

Fig. 54
figure54

Lanceolites compactus Hyatt and Smith 1905. All from the Owenites beds, Inyoites oweni horizons, Smithian; a, b UBGD 275081, loc. DH1-11, Confusion Range; ce UBGD 275082, loc. DH1-11, Confusion Range; f UBGD 275083, loc. DV1-7, Pahvant Range; g, h UBGD 275084, loc. DH1-12, Confusion Range; i, j UBGD 275085, loc. DV1-8, Pahvant Range; k suture line of UBGD 275086, loc. DH1-11, Confusion Range, scale bar is 5 mm (H = 33.4 mm)

1905 Lanceolites compactus; Hyatt and Smith, p. 113, pl. 4, figs. 4-10 ; pl. 5, figs. 7–9; pl. 78, figs. 9–11.

1932 Lanceolites compactus; Smith, p. 90, pl. 4, figs. 4–10; pl. 5, figs. 7–9; pl. 21, figs. 21–23; pl. 28, figs. 17–20; pl. 40, figs. 9–11; pl. 60, fig. 10.

1962 Lanceolites compactus; Kummel and Steele, p. 692, pl. 102, figs. 6–9.

? 1979 Lanceolites compactus; Nichols and Silberling, pl. 2, figs. 39–43.

1995 Lanceolites compactus; Shevyrev, p. 39, pl. 2, figs. 1–2.

v 2008 Lanceolites compactus; Brayard and Bucher, p. 61, pl. 30, fig. 5, text-fig. 53.

v 2012a Lanceolites compactus; Brühwiler and Bucher, p. 38, pl. 20, figs. 4–6.

Occurrence Present within the upper part of the Owenites beds, Inyoites oweni horizons of the Confusion Range, Pahvant Range, Torrey area and the Mineral Mountains, but less abundant than L. bicarinatus. Also found within the Owenites beds of South China, the Caucasus and Oman.

Description Occluded discoidal shell with slightly convex flanks. Venter tabulate or slightly sulcate with angular shoulders. Maximum curvature of flanks on their inner half. Whorl height rapidly expanding. Ornamentation not present on our specimens (low folds are known to occur on some previously described specimens). Suture line typical of the genus, subammonitic with broad and strongly indented lobes. Indentations are lanceolate.

Measurements See Fig. 55. Estimated maximum size: ~10 cm.

Fig. 55
figure55

Scatter diagrams of H, W and U, and H/D, W/D and U/D for Lanceolites (open symbols indicate specimens from the Confusion Range and Pahvant Range, Owenites beds, Inyoites oweni horizons [n = 12]; grey symbols indicate specimens from Vietnam, the Caucasus, Guangxi and Oman; data from Vu Khuc 1984, Shevyrev 1995, Brayard and Bucher 2008, Brühwiler et al. 2012a [n = 15]). The symbol C indicates specimens assigned to L. compactus

Discussion Smith (1932) established an additional species of Lanceolites: L. bicarinatus, based on specimens with a smaller whorl width and narrower venter. Kummel and Steele (1962) questioned the validity of L. bicarinatus and considered it to be simply an extreme compressed variant. Brayard and Bucher (2008), Brühwiler et al. (2012a) and Shevyrev (1995) published a few measurements that indicated these two species may be valid taxa. Unfortunately, the number of previously measured specimens was not enough to resolve the issue. New measured specimens reported here from Utah indicate that any distinction between the two species is tenuous and probably not confirmed (see Fig. 55). Since the number of measured specimens from worldwide locations is still inadequate to solve this issue, we prefer to continue to discriminate the two species. Also note that the illustrated specimens of L. compactus from the Caucasus (Shevyrev 1995) apparently exhibit a slightly thicker whorl section at a smaller size compared to our American specimens.

Lanceolites bicarinatus Smith, 1932

Fig. 56a–f

Fig. 56
figure56

Lanceolites bicarinatus Smith 1932. All from loc. DH1-11, Confusion Range, Owenites beds, Inyoites oweni horizons, Smithian; ac UBGD 275087; df UBGD 275088; d scale bar is 5 mm (H = 40 mm)

1932 Lanceolites bicarinatus; Smith, p. 90, pl. 55, figs. 1–13.

1959 Lanceolites orientalis; Chao, p. 263, pl. 41, figs. 5–9.

1984 Lanceolites bicarinatus; Vu Khuc, p. 85, pl. 7, figs. 2a, b, text-fig. H18.

1995 Lanceolites bicarinatus; Shevyrev, p. 40, pl. 4, fig. 3.

v 2008 Lanceolites bicarinatus; Brayard and Bucher, p. 62, pl. 30, fig. 6, text-fig. 53.

v 2010 Lanceolites bicarinatus; Stephen et al., figs. 6a, b, g.

Occurrence Relatively common in the upper part of the Owenites beds, Inyoites oweni horizons of the Confusion Range, Pahvant Range and the Mineral Mountains. Also found in South China, the Caucasus, Vietnam and Oman.

Description Identical to L. compactus, but with a smaller whorl width and a narrower venter that appears almost bicarinate. Ventral shoulders also angular. No ornamentation visible on our specimens. Suture line identical to L. compactus.

Measurements See Fig. 55. Estimated maximum size: ~10 cm.

Discussion This species supposedly differs from the type species by its narrower venter (see above).

Family Ussuriidae Spath, 1930

Genus Parussuria Spath, 1934

Type species Ussuria compressa Hyatt and Smith, 1905

Discussion Scarce morphological and measurement data for ussuriids prevent a thorough revision of the different potential taxa included in the family. Indeed, it appears that the coiling parameters for Parussuria and Metussuria are extremely close based on the few available data. These genera are therefore distinguished on characters that are subject to preservation bias such as the presence of a very weak ornamentation (Parussuria) or a larger juvenile whorl section (Metussuria). In lieu of future reported ussuriid occurrences with detailed morphological data, we thus follow the taxonomic assignments previously discussed in Brayard and Bucher (2008) and Brühwiler et al. (2012a).

Parussuria compressa (Hyatt and Smith, 1905)

Fig. 57a–f

Fig. 57
figure57

Parussuria compressa (Hyatt and Smith 1905). All from the Owenites beds, Inyoites oweni horizons, Smithian; ac UBGD 275089, loc. DV1-9, Pahvant Range; d, e UBGD 275090, loc. DH1-11, Confusion Range; f suture line of UBGD 275091, loc. DV1-8, Pahvant Range, scale bar is 5 mm (H = 22 mm)

1905 Ussuria compressa; Hyatt and Smith, p. 89, pl. 3, figs. 6–11.

1932 Sturia compressa; Smith, p. 93, pl. 3, figs. 6–11.

1934 Parussuria compressa; Spath, p. 213, figs. 66c, d.

1962 Parussuria compressa; Kummel and Steele, p. 690, pl. 99: 23; pl. 102, fig. 11.

? 1968 Parussuria semenovi; Zakharov, p. 59, pl.5, fig. 4.

1995 Parussuria compressa; Shevyrev, p. 37, pl. 4, fig. 6, text-fig. 16.

2008 Parussuria compressa; Brayard and Bucher, p. 56, pl. 12, fig. 17.

2012a Parussuria compressa; Brühwiler and Bucher, p. 31, pl. 18, figs. 8–14.

Occurrence Abundant in the Confusion Range, Pahvant Range and the Mineral Mountains, Owenites beds, Inyoites oweni horizons. Not documented from other sections.

Description Involute, compressed oxycone with a typical narrowly rounded venter. Flanks slightly convex with maximum lateral curvature near umbilicus, gradually converging to venter. Umbilicus nearly occluded, with moderately high, oblique wall and rounded shoulders. Ornamentation consists only of weak folds. Since the outer shell is not preserved on our sampled specimens, no strigation was observed. Traces of thin, radial growth lines are sometimes discernible on flanks. Suture line typical of ussuriids with highly frilled lobes and saddles.

Measurements See Fig. 58. Estimated maximum size: ~15 cm.

Fig. 58
figure58

Scatter diagrams of H, W and U, and H/D, W/D and U/D for Parussuria compressa (open symbols indicate complete specimens from the Pahvant Range [n = 2], Owenites beds, Inyoites oweni horizons; grey symbols indicate specimens from South China, California, Primorye, Oman, and the Caucasus; data from Brayard and Bucher 2008, Kummel and Steele 1962, Zakharov 1968, Brühwiler et al. 2012a, Shevyrev 1995 [n = 22])

Discussion Metussuria waageni and Parussuria compressa are both reported from the Lower Triassic beds of California (e.g., Hyatt and Smith 1905). M. waageni mainly differs from P. compressa by its larger juvenile whorl section and its absence of strigation. Our specimens do not show any strigation due to their poor preservation and absence of shell material. However, the conch coiling parameters of our complete but rare specimens are compatible with other known Parussuria compressa data.

Family Prionitidae Hyatt, 1900

Genus Wasatchites Mathews, 1929

Type species Wasatchites perrini Mathews, 1929

Wasatchites perrini Mathews, 1929

Figs. 13d and 59a–k

Fig. 59
figure59

Wasatchites perrini Mathews 1929. All from the Anasibirites kingianus beds, Smithian; a, b UBGD 275092, loc. DH1-13, Confusion Range; c, d UBGD 275093, loc. DH1-13, Confusion Range; e, f UBGD 275094, loc. DH1-13, Confusion Range; gi UBGD 275095, loc. RCA1, San Rafael Swell area; j, k UBGD 275096, loc. KA45/46, Kanarraville

1929 Wasatchites perrini; Mathews, p. 40, pl. 9, figs. 1–9

1929 Wasatchites meeki; Mathews, p. 41, pl. 7, figs. 1–3; pl. 8, figs. 11–14.

1929 Wasatchites magnus; Mathews, p. 41, pl. 11, figs. 1, 2.

1929 Wasatchites quadratus; Mathews, p. 42, pl. 7, figs. 23–25.

? 1929 Kashmirites thornei; Mathews, p. 38, pl. 6, figs. 22–25.

1929 Kashmirites wasatchensis; Mathews, p. 36, pl. 6, figs. 26–28.

? 1929 Kashmirites gilberti; Mathews, p. 38, pl. 7, figs. 4–8

1929 Keyserlingites seerleyi; Mathews, p. 39, pl. 8, figs. 8–10.

1932 Kashmirites meeki; Smith, p. 67, pl. 81, figs. 1, 2.

1932 Kashmirites wasatchensis; Smith, p. 69, pl. 81, figs. 3–5.

1932 Kashmirites perrini; Smith, p. 67, pl. 81, figs. 6–8.

1932 Kashmirites seerleyi; Smith, p. 68, pl. 81, figs. 11, 12.

p 1961 Wasatchites tardus; Tozer, p. 71, pl. 19, figs. 1a-b (only).

1994 Wasatchites perrini; Tozer, p. 79, pl. 29, figs. 5a-c; pl. 35, figs. 2-4.

v 2010 Wasatchites perrini; Stephen et al., fig. 7c.

Occurrence Present in the Confusion Range, Pahvant Range, Star Range, Cedar City, Kanarraville, Torrey and San Rafael Swell areas, Anasibirites kingianus beds. Not documented in Mineral Mountains.

Description Moderately involute, compressed shell with convex flanks forming a trapezoidal whorl section. Venter ranging from tabulate on some inner whorls to subtabulate or slightly arched on mature whorls, characteristic of Prionitidae, with bluntly angular ventral shoulders. Umbilicus relatively shallow with a typical oblique wall and rounded shoulders. Ornamentation very conspicuous exhibiting projected fold-like ribs varying slightly in strength and width. They typically alternate between strong and weak. Ribs are also typically fasciculate, and may stem from strong tubercles on umbilical shoulders becoming stronger and more bullate or nodate on mature whorls. Ribs do not fade away on outer half of the flanks, but instead continue onto ventral shoulders and are well visible as they cross the venter. Suture line ceratitic with rather deep lateral lobes and broad, rounded saddles, but always poorly preserved on our specimens.

Measurements See Fig. 60. Estimated maximum size: ~15 cm.

Fig. 60
figure60

Scatter diagrams of H, W and U, and H/D, W/D and U/D for Wasatchites species. Open symbols indicate complete measurable specimens of W. perrini from the Confusion Range, Anasibirites kingianus beds; grey symbols indicate W. perrini and W. tridentinus from British Columbia (Tozer 1994, [n = 3]) and W. distractus from the Spiti and Salt Range (Brühwiler et al. 2012b, c; [n = 128])

Discussion Wasatchites is a cosmopolitan genus, found for instance in the USA, British Columbia, Arctic Canada, Spitsbergen, Russia, Pakistan (Salt Range), Spiti, Timor and Afghanistan. This taxon is relatively rare in central and eastern Utah compared to the famous late Smithian prionitid Anasibirites. However, W. perrini is also a typical late Smithian taxon that is helpful for biostratigraphical correlation (e.g., the Anawasatchites tardus Zone from British Columbia is a correlative of the A. kingianus beds described in this work).

Wasatchites species may exhibit highly variable ornamentation and a very wide intraspecific variation as do almost all Prionitidae. A correct species assignment is therefore sometimes difficult. Differentiation with other prionitid genera is possible based on the associated marked tuberculation with multiple projected fasciculate or radial ribs originating from the tubercles and crossing the venter.

W. distractus (mainly documented from the Tethys area) essentially differs from the type species by the more lateral position of the spines on the flank and the more radial and conspicuous ribs that appear to diminish at maturity. W. tridentinus (British Columbia, Spitsbergen) displays strong bullae on only half a whorl of the body chamber (Tozer 1994). Compared to the type species, W. deleeni (British Columbia) presents fewer bullae on the phragmocone and a more ovoid whorl section. W. procurvus (British Columbia) differs from all other species by distinctive ribs crossing the venter with a conspicuous forward projected curvature.

Genus Anasibirites Mojsisovics, 1896

Type species Sibirites kingianus Waagen, 1895

Discussion Pending a thorough revision of the potentially different Anasibirites species, we follow the taxonomic assignments previously discussed in Brayard and Bucher (2008) and Brühwiler et al. (2012a, c). The three species illustrated below may therefore be encompassed into a single conspecific American species as previously suggested by some authors (e.g., Kummel and Erben 1968). Indeed, these species generally cannot be identified based only on their measurements (Fig. 61), and are mainly distinguished only by the strength of their ornamentation, which may conform to the Buckman’s first law of covariation (Westermann 1966).

Fig. 61
figure61

Box plots of H/D, W/D and U/D for Anasibirites species considered in this work. Data for A. multiformis Utah (this work), Guangxi (Brayard and Bucher 2008), Timor and Afghanistan (Kummel and Erben 1968). Data for A. kingianus Utah (this work), Salt Range (Brühwiler et al. 2012c) and Tibet (Brühwiler et al. 2010b). Data for A. angulosus Utah (this work) and Salt Range (Brühwiler et al. 2012c)

Anasibirites kingianus (Waagen, 1895)

Fig. 62a–k

Fig. 62
figure62

Anasibirites kingianus (Waagen 1895). All from the Anasibirites kingianus beds, Smithian; ac UBGD 275097, loc. FFA3, Torrey area; c scale bar is 5 mm (H = 23 mm); d UBGD 275098, loc. KA45/46, Kanarraville; eg UBGD 275099, loc. RCA1, San Rafael Swell area; g scale bar is 5 mm (H = 25.3 mm); h, i UBGD 275100, loc. FFA3, Torrey area; j, k UBGD 275101, loc. RCA1, San Rafael Swell area

1895 Sibirites kingianus; Waagen, p. 108, pl. 8, figs. 1, 2.

1895 Sibirites chidruensis; Waagen, p. 109, pl. 8, figs. 3, 4.

1895 Sibirites inaequicostatus; Waagen, p. 113, pl. 8, figs. 7, 8.

? 1895 Sibirites ceratitoides; Waagen, p. 115, pl. 8, fig. 10.

? 1905 Sibirites noetlingi; Hyatt and Smith, p. 49, pl. 9, figs. 1–3.

1909 Sibirites spiniger; Krafft and Diener, p. 131, pl. 31, figs. 2–7.

1909 Sibirites robustus; Krafft and Diener, p. 132, pl. 31, fig. 1.

? 1909 Sibirites sp. indet. ex aff. robusto; Krafft and Diener, p. 133, pl. 31, fig. 6.

? 1909 Sibirites spitiensis; Krafft and Diener, p. 136, pl. 31, fig. 8.

p 1909 Sibirites sp. indet.; Krafft and Diener, p. 138, pl. 31, figs. 4, 5.

1929 Anasibirites kingianus; Mathews, p. 8, pl. 7, figs. 14–22.

1929 Anasibirites perrini; Mathews, p. 18, pl. 3, figs. 34–36.

1932 Anasibirites kingianus var. inaequicostatus; Smith, p. 72, pl. 79, figs. 16, 17.

1968 Anasibirites kingianus; Kummel and Erben, p. 135, pl. 22, figs. 12-17; pl. 23, figs. 1–18.

? 1974 Anasibirites kingianus; Skwarko and Kummel, pl. 40, figs. 2–7.

1978 Anasibirites kingianus; Guex, pl. 3, figs. 2, 9; pl. 4, figs. 6.

1981 Meekoceras sp.; Dean, pl. 1, fig. 5.

? 2007a Anasibirites kingianus; Lucas et al., p. 104, figs. 3h-j only; figs. 4a,b, e–h, j–l.

2010 Anasibirites kingianus; Stephen et al., fig. 7a, b.

2012b Anasibirites kingianus; Brühwiler et al., p. 155, figs. 31O, 32AA–BD.

2012c Anasibirites kingianus; Brühwiler and Bucher, p. 101, figs. 84A–U.

Occurrence Common in all sections within the Anasibirites kingianus beds.

Description Moderately involute, compressed shell with convex flanks forming a trapezoidal whorl section. Venter low, arched with rounded shoulders. Umbilicus relatively shallow with an oblique to almost perpendicular wall and rounded shoulders. Well visible ornamentation consisting of an alternation of sinuous, projected fold-like ribs varying in strength and width. Ribs strongly attenuated on adult specimens. Suture line ceratitic with rather deep lateral lobes. Saddles broad and rounded.

Measurements See Figs. 61 and 63. Estimated maximum size: ~10 cm.

Fig. 63
figure63

Scatter diagrams of H, W and U, and H/D, W/D and U/D for Anasibirites species (complete specimens from the Confusion Range, Anasibirites kingianus beds [n = 9]). ang. and mul. indicate the A. angulosus and A. multiformis specimens

Anasibirites multiformis Welter, 1922

Fig. 64a–g

Fig. 64
figure64

Anasibirites multiformis Welter 1922. All from the Anasibirites kingianus beds, Smithian; a, b UBGD 275102, loc. DH1-13, Confusion Range; c, d UBGD 275103, loc. DH1-13, Confusion Range; eg UBGD 275104, loc. RCA1, San Rafael Swell area

?p 1895 Sibirites tenuistriatus; Waagen, p. 124, pl. 9, figs. 2a–b.

p 1922 Anasibirites multiformis; Welter, p. 138, pl. 15, figs. 12, 13, 23, 24; pl. 16, figs. 6–19.

? 1929 Anasibirites welleri; Mathews, p. 14, pl. 2, figs. 17–19.

? 1929 Anasibirites emmonsi; Mathews, p. 14, pl. 2, figs. 20–26.

? 2007a Anasibirites kingianus; Lucas et al., p. 104, figs. 3d–g only.

v 2008 Anasibirites multiformis; Brayard and Bucher, p. 56, pl. 28, figs. 1–6.

v 2012a Anasibirites multiformis; Brühwiler and Bucher, p. 33, pl. 19, figs. 1–6.

Occurrence Common in all sections within the Anasibirites kingianus beds.

Description Moderately involute, compressed shell with slightly convex flanks. Tabulate to subtabulate venter on inner whorls and subtabulate to arched on mature whorls, with bluntly angular ventral shoulders. Umbilicus relatively shallow with an oblique wall and rounded shoulders. Ornamentation typically consists of dense, concave, fine and projected ribs crossing the venter. Suture line ceratitic with broad and rounded saddles, similar to A. kingianus.

Measurements See Figs. 61 and 63. Estimated maximum size: ~10 cm.

Discussion In contrast with other Anasibirites species, the ribs of A. multiformis are not pronounced and they do not alternate with weak ribs and growth lines. Its venter is also tabulate to subtabulate.

Anasibirites cf. angulosus (Waagen, 1895)

Fig. 65a–g

Fig. 65
figure65

Anasibirites cf. angulosus (Waagen 1895). All from the Anasibirites kingianus beds, Smithian; a, b UBGD 275105, loc. DH1-13, Confusion Range; c, d UBGD 275106, loc. RCA1, San Rafael Swell area; eg UBGD 275107, loc. RCA1, San Rafael Swell area

1895 Sibirites angulosus; Waagen, p. 117, pl. 8, figs. 12, 13.

1895 Sibirites ibex; Waagen, p. 121, pl. 9, fig. 3.

1895 Sibirites hircinus; Waagen, p. 123, pl. 9, figs. 12, 13.

? 2007a Meekoceras sp.; Lucas et al., p. 104, Fig. 3a only.

2012c Anasibirites angulosus; Brühwiler and Bucher, p. 103, figs. 84V–AA, 86A–U, 87A–P.

Occurrence Rare in the Confusion Range and San Rafael Swell area, Anasibirites kingianus beds.

Description Slightly involute compressed shell with slightly convex flanks. Tabulate venter with angular shoulders. Shallow umbilicus with an oblique wall and rounded shoulders. Ornamentation consists of dense, concave, projected ribs crossing the venter. Sometimes ribs thicken forming elongated tubercles. Suture line ceratitic with broad and rounded saddles, similar to A. kingianus.

Measurements See Figs. 61 and 63. Estimated maximum size: ~15 cm.

Discussion A. cf. angulosus differs from other Anasibirites species by its concave ribs forming elongated tubercles. Our rare complete specimens display sparser ribs and a more compressed whorl section than specimens from the Salt Range (see Brühwiler et al. 2012c), thus preventing a definitive assignment to this species.

Genus Hemiprionites Spath, 1929

Type species Goniodiscus typus Waagen, 1895

Hemiprionites cf. typus (Waagen, 1895)

Fig. 66a–g

Fig. 66
figure66

Hemiprionites cf. typus (Waagen 1895). All from the Anasibirites kingianus beds, Smithian; a, b UBGD 275108, loc. DH1-13, Confusion Range; ce UBGD 275109, loc. DH1-13, Confusion Range; f, g UBGD 275110, loc. DH1-13, Confusion Range

1895 Goniodiscus typus; Waagen, p. 128, pl. 9, figs. 7–10.

1929 Goniodiscus typus; Mathews, p. 31, pl. 5, figs. 12–21.

1929 Goniodiscus americanus; Mathews, p. 32, pl. 5, figs. 22–27.

1929 Goniodiscus shumardi; Mathews, p. 33, pl. 6, figs. 11–14.

? 1929 Goniodiscus utahensis; Mathews, p. 33, pl. 6, figs. 29–31.

? 1929 Goniodiscus ornatus; Mathews, p. 34, pl. 65, figs. 6–9.

1932 Anasibirites typus; Smith, p. 76, pl. 80, figs. 6-8.

? 1932 Anasibirites utahensis; Smith, p. 77, pl. 80, figs. 9, 10.

? 1932 Anasibirites ornatus; Smith, p. 75, pl. 80, figs. 11, 12.

1934 Hemiprionites typus; Spath, p. 33, figs. 114a–c.

2012c Hemiprionites typus; Brühwiler and Bucher, p.103, figs. 89A–AH.

Occurrence One specimen from the Pahvant Range and three fragmentary shells from the Confusion Range, Anasibirites kingianus beds.

Description Moderately involute, compressed shell with deeply embracing whorls and slightly egressive coiling. Flanks convex and convergent, but showing a typical depression near the ventral shoulders. Maximum curvature of the flanks near mid-flank. Venter tabulate to weakly sulcate in rare instances. Ventral shoulders bluntly angular. Umbilical shoulders broadly rounded forming a deep umbilicus with an inclined wall. Ornamentation visible on our poorly preserved specimens consists of very low radial folds that sometimes cross the venter. Flexuous growth lines are superimposed onto folds. Suture line not visible on our specimens.

Measurements See Table 1.

Discussion Our specimens are similar to the type species. However, because of their poor preservation, it cannot be determined if the “keel” or weak ventral spiral lines observed respectively by Mathews (1929) and Brühwiler et al. (2012c) is present on our specimens, thus precluding their definitive assignment to the type species. They may also appear slightly more laterally compressed compared to the recently illustrated specimens from the Salt Range (Brühwiler et al. 2012c).

Nearly all Hemiprionites species occur in the Anasibirites kingianus beds (H. roberti is from the uppermost Meekoceras bed at Crittenden Springs, Nevada; Jenks et al. 2010) and most of the previously described taxa can be included within the type species variation. H. roberti from Crittenden Springs (Jenks et al. 2010), H. butleri from northern Utah (Mathews 1929) and Guangxi (Brayard and Bucher 2008) and H. klugi from Guangxi (Brayard and Bucher 2008) and the Salt Range (Brühwiler et al. 2012c) mainly differ from the type species by their involute coiling and funnel-like umbilicus.

Genus Arctoprionites (Frebold, 1930)

Type species Goniodiscus nodosus Frebold, 1930.

Arctoprionites resseri (Mathews, 1929)

Fig. 67a–e

Fig. 67
figure67

Arctoprionites resseri (Mathews 1929). All from the Anasibirites kingianus beds, Smithian; ac UBGD 275111, loc. RCA1, San Rafael Swell area; c scale bar is 5 mm (H = 21.5 mm); d, e UBGD 275112, loc. KA45/46, Kanarraville

1929 Kashmirites resseri; Matthews, p. 38, pl. 8, figs. 4–7.

1932 Kashmirites resseri; Smith, p. 67, pl. 81, figs. 9, 10.

1961 Arctoprionites sp. indet.; Tozer, pl. 20, fig. 1.

v. 1962 Arctoprionites sp. indet.; Kummel and Steele, p. 699, pl. 101, fig. 2.

1994 Arctoprionites williamsi; Tozer, p. 83, pl. 34, figs. 1–4.

Occurrence Rare in the San Rafael Swell and Kanarraville [n = 4]. All from the Anasibirites kingianus beds.

Description Moderately involute coiling similar to Anasibirites or Wasatchites. Flanks slightly convex forming a trapezoidal whorl section. On small immature whorls, a weak depression near the ventral shoulders, as in Hemiprionites, is discernible. Venter markedly flat with bluntly angular shoulders. Umbilical shoulders broadly rounded forming a deep umbilicus with an inclined wall. Our specimens exhibit slightly projected, angular and elongated bullae near the umbilical margin. Bullae fade away near mid-flank but weak folds sometimes persist, forming a crenulation on the ventral shoulder on smaller specimens. Folds generally do not cross the venter, but on occasion they leave a perceptible weak trace on smaller specimens. Growth lines not visible on our specimens. Suture line ceratitic with broad rounded saddles and deep lateral lobes.

Measurements See Table 1.

Discussion This is the first report of Arctoprionites from Utah. Arctoprionites sp. indet. illustrated from Nevada by Kummel and Steele (1962) is probably conspecific with A. resseri. Arctoprionites resseri mainly differs from the Arctic species A. nodosus (Frebold, 1930) by its umbilical bullae. Surprisingly, the Spitsbergen specimen that Weitschat and Lehmann (1978) chose to illustrate exhibits only very weak bullae, whereas specimens originally described by Frebold (1930) as well as other specimens from Spitsbergen (J. Jenks, personal observation) exhibit quite prominent bullae. A. williamsi described from Arctic Canada by Tozer (1961, 1994) closely resembles A. resseri. The description of A. williamsi by Tozer (1994) with its more elevated bullae appears doubtful and thus, we consider A. resseri and A. williamsi as conspecific.

Some specimens of Anasibirites angulosus may exhibit similar elongated umbilical tubercules but the whorl section of this species appears more laterally compressed and the tubercles are irregularly spaced. Ribs of Anasibirites angulosus also cross the venter. The older prionitid, Punjabites punjabiensis, from the Salt Range (Brühwiler et al. 2012c) displays the same type of projected and elongated umbilical bullae, but its venter is rounded.

Genus Meekoceras Hyatt in White, 1879

Type species Meekoceras gracilitatis White, 1879

Discussion We follow herein the taxonomic assignment of Brühwiler et al. (2012c) of Meekoceras to the Prionitidae. Indeed, Meekoceras shares many of the same features as most prionitids (i.e., similar whorl shape, umbilicus and suture line), thus justifying its assignment.

Meekoceras gracilitatis White, 1879

Fig. 68a–j

Fig. 68
figure68

Meekoceras gracilitatis White 1879. ac UBGD 275113, loc. FFA1, Torrey area, Owenites beds, Smithian; d scale bar is 5 mm (H = 31.3 mm); e, f UBGD 275114, loc. DH1-9, Confusion Range, Owenites beds, Smithian; gj UBGD 275115, loc. DH1-6, Confusion Range, between the Owenites beds and the Inyoites beaverensis sp. nov. beds, Smithian; g scale bar is 5 mm (H = 30.6 mm)

1879 Meekoceras gracilitatis; White, p. 114.

1880 Meekoceras gracilitatis; White, p. 115, pl. 31, fig. 2.

1902 Meekoceras gracilitatis; Frech, p. 631, fig. 2.

p 1904 Meekoceras gracilitatis; Smith, p. 370, pl. 42, only fig. 1; pl. 43, figs. 3, 4.

1905 Meekoceras gracilitatis; Hyatt and Smith, p. 143, pl. 12, figs. 1–13; pl. 13, figs. 1–18; pl. 14, figs. 1–8; pl. 70, figs. 4–7.

p 1932 Meekoceras gracilitatis; Smith, p. 57, pl. 12, figs. 1–13; pl. 13, figs. 1–18; pl. 14, figs. 1–8; pl. 36, figs. 19–28; pl. 37, figs. 1–7; pl. 38, figs. 2, 3 and 5-6 only; pl. 70, figs. 4–7.

1961 Meekoceras gracilitatis; Tozer; p. 65, pl. 15, fig. 6; pl. 17, figs. 1-3; pl. 18, figs. 4–6.

1962 Meekoceras gracilitatis; Kummel and Steele, p. 693, pl. 103, figs. 1–6.

1968 Meekoceras gracilitatis; Kummel and Erben, p. 129, pl. 20, figs. 1–3, 8–13.

1979 Meekoceras gracilitatis; Nichols and Silberling, p. B3, pl. 1, figs. 1–4.

1990 Meekoceras gracilitatis; Dagys and Ermakova, p. 35, pl. 6, fig. 5; pl. 7, fig. 1; pl. 8, figs. 1, 2.

? 1994 Meekoceras gracilitatis; Tozer, p. 70, pl. 21, fig. 2.

non 1995 Meekoceras gracilitatis; Shevyrev, p. 29, pl. 2, fig. 3.

Occurrence Uncommon in all studied sections from the KashmiritesPreflorianites beds to the Inyoites oweni beds. Not found in Kanarraville and San Rafael Swell areas.

Description Moderately involute coiling and compressed, similar to Anasibirites or Wasatchites. Flanks slightly convex forming a trapezoidal whorl section. Venter sulcate (true bicarinate venter) on Utah specimens, especially at large size with very angular shoulders. Umbilicus with inclined wall and broadly rounded shoulders forming an intermediate deep umbilicus. Ornamentation often consists of rare barely perceptible projected folds. Folds never cross the venter. Suture line ceratitic with fairly low saddles.

Measurements See Figs. 69 and 70. Estimated maximum size: ~20 cm.

Fig. 69
figure69

Scatter diagrams of H, W and U, and H/D, W/D and U/D for Meekoceras gracilitatis (open symbols indicate specimens from the Confusion Range and Pahvant Range, Owenites beds [n = 2]; grey symbols indicate specimens from Nevada; data from Jenks et al. 2010 [n = 101]; Jenks et al. 2010 also described “evolute” specimens which are not illustrated here see Fig. 70)

Fig. 70
figure70

Box plots of H/D, W/D and U/D for Meekoceras gracilitatis from Utah (this work) and Nevada (Jenks et al. 2010), “evolute” M. cf. gracilitatis from Nevada (Jenks et al. 2010) and Salt Range (Brühwiler et al. 2012c), M. cf. gracilitatis from the Canadian Arctic (Tozer 1961, 1994) and M. subcristatum from South Primorye (Zakharov 1968)

Discussion True Meekoceras gracilitatis specimens are relatively easy to distinguish when their preservation is rather good. Indeed, such well-preserved material often exhibits both the typical sulcate venter and the inclined umbilical wall. However, on the Utah specimens the bicarinate venter is often eroded and even becomes tabulate when the specimens are poorly preserved, which is often the case in the studied sections. Consequently, the overall shape of such specimens is extremely close to weathered specimens of Hemiprionites and Anasibirites, as well as forms of Wasatchites and Arctoprionites that display very weak ornamentation. Furthermore, the suture line is not diagnostic as is the case with most prionitids. This may explain why many authors have often reported numerous successive beds with Meekoceras or confused the Anasibirites kingianus beds with older levels where Meekoceras does occur. For instance, Lucas et al. (2007a) reported the co-occurrence of Meekoceras sp. with Anasibirites and Wasatchites in the San Rafael Swell. However, this attribution is rather unlikely due to the poor preservation of the specimens, which are closer to late Smithian ornamented prionitids such as Anasibirites. Moreover, as far as we know, it would represent the only worldwide occurrence of this genus within the Anasibirites kingianus beds. We failed to find this genus within the late Smithian beds of the San Rafael Swell.

Brühwiler et al. (2012c), Jenks et al. (2010) and Tozer (1961, 1994) described respectively from the Salt Range, Nevada and southeast Idaho, and the Canadian Arctic, “more evolute” specimens of M. gracilitatis without showing robust statistical tests confirming this hypothesis due to the paucity of data. However, we have combined their data and compared them to M. gracilitatis measurements. As expected, a segregation between these two groups seems to exist, but it has not yet been statistically confirmed (see Fig. 70).

Several Meekoceras species described by Smith (1932; e.g., M. arthaberi, M. sylvanum) probably can be synonymized with the type species, but we need additional material from Smith’s studied sections to confirm this hypothesis. M. cristatum is probably a distinct species characterized by its distinctive folds and ribs, which sometimes modify the venter in such a way that it becomes slightly corrugated (Smith 1932 and personal observation of the first author of specimens from southeast Idaho).

Specimens from the Caucasus assigned to M. gracilitatis (Shevyrev 1995) are doubtful because the whorl section appears to be quadrangular and too thick, and the umbilicus is too deep. They also do not have a bicarinate venter. M. subcristatum from South Primorye (Zakharov 1968) mainly differs from the type species by its more conspicuous ornamentation, slightly more evolute coiling and thicker whorl section (Fig. 70).

Meekoceras olivieri sp. nov.

Fig. 71a–l

Fig. 71
figure71

Meekoceras olivieri sp. nov. All from the Meekoceras olivieri sp. nov. beds, loc. DV2-200, Pahvant Range, Smithian; a, b UBGD 275116, holotype; c, e UBGD 275117, paratype; fh UBGD 275118, paratype; h scale bar is 5 mm (H = 38.5 mm); i, j UBGD 275119, paratype; k, l UBGD 275120, paratype

Holotype UBGD 275116 (Fig. 71a, b), loc. DV2-200, Pahvant Range, Meekoceras olivieri sp. nov. beds, Smithian.

Derivation of name Species named after Nicolas Olivier (Lyon).

Diagnosis Very similar to the type species of Meekoceras, but differing by a tabulate venter that becomes arched at a large size.

Occurrence Rare (10 specimens) from the Pahvant Range within the Meekoceras olivieri sp. nov. beds [DV200].

Description Moderately involute coiling and compressed, similar to M. gracilitatis. Venter at small and medium sizes appears to be tabulate with marked rounded shoulders. Venter becomes arched at a large size and ventral shoulders become indistinct. Ornamentation on our largest specimens consists only of large folds. Suture line similar to M. gracilitatis.

Measurements See Fig. 72. Estimated maximum size: ~15 cm.

Fig. 72
figure72

Scatter diagrams of H, W and U, and H/D, W/D and U/D for Meekoceras olivieri sp. nov., Meekoceras olivieri sp. nov. beds

Discussion This taxon exhibits the same overall features as the type species. However, it can be distinguished by its arched venter at larger sizes, which contrasts with the typical sulcate venter of M. gracilitatis. At smaller sizes, and especially if specimens are weathered, these two species are almost indistinguishable. M. olivieri sp. nov. represents the oldest occurrence of Meekoceras in Utah.

Meekoceras millardense sp. nov.

Fig. 73a–g

Fig. 73
figure73

Meekoceras millardense sp. nov. All from the Meekoceras millardense sp. nov. bed, loc. DV2-0, Pahvant Range, Smithian; ad UBGD 275121, holotype; d scale bar is 5 mm (H = 38.5 mm); eg UBGD 275122, paratype

Holotype UBGD 275121 (Fig. 73a–d), loc. DV2-0, Pahvant Range, Meekoceras millardense sp. nov. bed, Smithian.

Derivation of name Name refers to its occurrence in Millard County (Utah).

Diagnosis Very similar to the type species of Meekoceras, but differing by its involute coiling.

Occurrence Rare (2 specimens) from the Pahvant Range within the Meekoceras millardense sp. nov. bed [DV2-0].

Description Involute and compressed shell with a tabulate venter. Ventral margins bluntly angular with very delicate keels when preserved. Flanks convex. Umbilicus almost occluded. No ornamentation displayed on our specimens. Suture line similar to M. gracilitatis, but apparently with lower saddles and delicately crenulated lobes.

Measurements See Table 1. Estimated maximal size: ~5 cm.

Discussion This taxon differs from other Meekoceras species by its involute coiling, but its other shell characters are extremely similar.

Family Parannanitidae Spath, 1930

Genus Owenites Hyatt and Smith, 1905

Type species Owenites koeneni Hyatt and Smith, 1905

Owenites koeneni Hyatt and Smith, 1905

Fig. 74a–i

Fig. 74
figure74

Owenites koeneni Hyatt and Smith 1905. All from the Owenites beds, Smithian; ad UBGD 275123, loc. DH1-9, Confusion Range; d scale bar is 5 mm (H = 18 mm); eg UBGD 275124, loc. DH1-9, Confusion Range; h, i UBGD 275125, loc. DV1-8, Pahvant Range

1905 Owenites koeneni; Hyatt and Smith, p. 83, pl. 10, figs. 1–22.

1915 Owenites koeneni; Diener, p. 214.

1932 Owenites koeneni; Smith, p. 100, pl. 10, figs. 1–22.

1932 Owenites egrediens; Smith, p. 100, pl. 52, figs. 6–8.

1932 Owenites zitteli; Smith, p. 101, pl. 52, figs. 1–5.

1934 Owenites koeneni; Spath, p. 185, fig. 57.

1947 Owenites aff. egrediens; Kiparisova, p. 139, pl. 32, figs. 1–3.

1955 Kingites shimizui; Sakagami, p. 138, pl. 2, figs. 2a–c.

1957 Owenites koeneni; Kummel in Arkell et al., p. L138, figs. 171-8a–b.

v 1959 Owenites costatus; Chao, p. 249, pl. 22, figs. 10-18, 22, 23, text-fig. 26c.

v 1959 Owenites pakungensis; Chao, p. 248, pl. 21, figs. 6–8.

v 1959 Owenites pakungensis var. compressus; Chao, p. 248, pl. 21, figs. 4, 5.

v 1959 Pseudowenites oxynotus; Chao, p. 252, pl. 23, figs. 1-16, text-figs. 27a–d.

1959 Owenites shimizui; Kummel, p. 430.

1960 Owenites shimizui; Kummel and Sakagami, p. 6, pl. 2, figs. 5, 6.

1962 Owenites koeneni; Kummel and Steele, p. 674, pl. 101, figs. 3–7.

1962 Owenites koeneni; Popov, p. 44, pl. 6, fig. 6.

1965 Owenites koeneni; Kuenzi, p. 374, pl. 53, figs. 1–6, text-figs. 3d, 6.

1966 Owenites koeneni; Hada, p. 112, pl. 4, figs. 2–4.

1968 Owenites koeneni; Kummel and Erben, p. 121, figs. 12; pl. 19, figs. 10–15.

1968 Owenites carinatus; Shevyrev, p. 189, pl. 16, fig. 1.

1968 Owenites koeneni; Zakharov, p. 94, pl. 18, figs. 1–3.

1973 Owenites koeneni; Collignon, p. 139, pl. 4, figs. 2, 3.

1979 Owenites koeneni; Nichols and Silberling, pl. 1, figs. 17, 18.

1981 Owenites koeneni; Bando, p. 158, pl. 17, fig. 7.

1984 Owenites carinatus; Vu Khuc, p. 81, pl. 6, figs. 1–4, text-fig. H16.

1984 Pseudowenites oxynotus; Vu Khuc, p. 82, pl. 7, figs. 3, 4.

1990 Owenites koeneni; Shevyrev, p. 118, pl. 1, fig. 5.

1995 Owenites koeneni; Shevyrev, p. 51, pl. 5, figs. 1–3.

? 2004 Owenites pakungensis; Tong et al., p. 199, pl. 2, figs. 9-10, text-fig. 7.

v. 2008 Owenites koeneni; Brayard and Bucher, p. 67, pl. 36, figs. 1–8, fig. 58.

v. 2010b Owenites koeneni; Brühwiler et al., p. 426, fig. 15(9).

v. 2012a Owenites koeneni; Brühwiler and Bucher, p. 43, pl. 25, figs. 1–6.

Occurrence Rare in all sections, Owenites beds. Not found in the Torrey area. Common at Crittenden Springs (Nevada) and southeastern Idaho.

Description Almost involute, somewhat compressed shell with an inflated, lenticular whorl section and a typical, subangular to angular venter that may resemble a keel on mature specimens. Narrow, shallow umbilicus, with a very low, steep wall and narrowly rounded shoulders. Whorl height and umbilical diameter of O. koeneni display significant allometric growth (Brayard and Bucher 2008). Egressive coiling at maturity. Surface generally smooth, but may exhibit weak, forward projected constrictions and folds. Suture line ceratitic with several divided umbilical lobes.

Measurements See Table 1. Estimated maximum size: ~8 cm (see Brayard and Bucher 2008).

Discussion For a thorough discussion of O. koeneni systematics, please refer to Brayard and Bucher (2008). Our illustrated specimens appear somewhat more compressed than the holotype and paratypes of Hyatt and Smith (1905), and the South China specimens. Other characters appear to be similar. Owenites species are typical of the mid and upper parts of the middle Smithian and of the Early Triassic tropical belt.

Owenites carpenteri Smith, 1932

Fig. 75a–f

Fig. 75
figure75

Owenites carpenteri Smith 1932. All from the Owenites beds, Smithian; a, b UBGD 275126, loc. DH1-12, Confusion Range; cf UBGD 275127, loc. DV1-8, Pahvant Range

1932 Owenites carpenteri; Smith, p. 100, pl. 54, figs. 31–34.

1966 Owenites carpenteri; Hada, p. 112, pl. 4, figs. 1a–e.

1968 Owenites costatus; Kummel and Erben, p. 122, fig. 12l.

1973 Owenites carpenteri; Collignon, p. 139, pl. 4, figs. 5, 6.

v 2008 Owenites carpenteri; Brayard and Bucher, p. 70, pl. 43, figs. 15, 16.

2010b Owenites carpenteri; Brühwiler et al., p. 426, fig. 16(7, 8).

v 2012a Owenites carpenteri; Brühwiler and Bucher, p. 44, pl. 25, figs. 7, 8.

Occurrence Relatively rare in all sections, Owenites beds. Not documented from the Torrey area. Also found in northeastern Nevada (Cottonwood Canyon and Crittenden Springs), South China, Spiti and Oman.

Description Small, involute and compressed oxyconic shell. Venter subangular to narrowly rounded. Whorl section slightly inflated and lenticular. Flanks convex from the occluded umbilicus. Maximum thickness near the umbilicus. A few folds are displayed on the shell. Some distant constrictions may be present on internal mold. Suture line similar to O. koeneni.

Measurements See Fig. 76. Estimated maximum size: ~3.5 cm.

Fig. 76
figure76

Scatter diagrams of H, W and U, and H/D, W/D and U/D for Owenites carpenteri (open symbols indicate specimens from the Confusion Range and Pahvant Range, Owenites beds [n = 3]; grey symbols indicate specimens from Guangxi, Tibet, Spiti and Oman; data from Brayard and Bucher 2008, Brühwiler et al. 2010b, 2012a, b; [n = 16])

Discussion For a complete discussion regarding the ornamentation of this species, please refer to Brühwiler et al. (2012a). O. carpenteri can be easily distinguished from the type species and O. simplex by its occluded umbilicus and narrowly curved venter.

Family Hedenstroemiidae Waagen, 1895

Genus Pseudosageceras Diener, 1895

Type species Pseudosageceras sp. indet. Diener, 1895

Pseudosageceras multilobatum Noetling, 1905

Fig. 77a–f

Fig. 77
figure77

Pseudosageceras multilobatum Noetling 1905. a, b UBGD 275128, loc. DH1-9, Confusion Range, Owenites beds, Smithian; c, d UBGD 275129, loc. DV2-7, Pahvant Range, Owenites beds, Smithian; e suture line of UBGD 275130, loc. DH1-2, Confusion Range, Preflorianites–Kashmirites beds, Smithian, scale bar is 5 mm (H = 49 mm); f UBGD 275140, loc. DH1-1, Confusion Range, Preflorianites–Kashmirites beds

1905 Pseudosageceras multilobatum; Noetling, pl. 25, fig. 1, pl. 26, fig. 3.

1905 Pseudosageceras intermontanum; Hyatt and Smith, p. 99, pl. 4, figs. 1–3; pl. 5, figs. 1–6; pl. 63, figs. 1, 2.

1909 Pseudosageceras multilobatum; Krafft and Diener, p. 145, pl. 21, fig. 5.

1911 Pseudosageceras drinense; Arthaber, p. 201, pl. 17, figs. 6, 7.

1913 Pseudosageceras multilobatum; Wanner, p. 181, pl. 7, fig. 4.

1922 Pseudosageceras multilobatum; Welter, p. 94, fig. 3.

1929 Pseudosageceras intermontanum; Mathews, p. 3, pl. 1, figs. 18–22.

1932 Pseudosageceras multilobatum; Smith, p. 87-89, pl. 4, figs. 1–3; pl. 5, figs. 1–6; pl. 25, figs. 7–16; pl. 60, fig. 32; pl. 63, figs. 1–6.

1934 Pseudosageceras multilobatum; Collignon, p. 56-58, pl. 11, fig. 2.

1934 Pseudosageceras multilobatum; Spath, p. 54, fig. 6a.

1947 Pseudosageceras multilobatum; Kiparisova, p. 127, pl. 25, figs. 3, 4.

1947 Pseudosageceras multilobatum var. giganteum; Kiparisova, p. 127, pl. 26, figs. 2–5.

1948 Pseudosageceras cf. clavisellatum; Renz and Renz, p. 90, pl. 16, fig. 3.

1948 Pseudosageceras drinense; Renz and Renz, p. 92, pl. 16, fig. 6.

1948 Pseudosageceras intermontanum; Renz and Renz, p. 90, pl. 16, figs. 4, 7.

v 1959 Pseudosageceras multilobatum; Chao, p. 183, pl. 1, figs. 9, 12.

v 1959 Pseudosageceras tsotengense; Chao, p. 184, pl. 1, figs. 7, 8, text-fig. 5b.

v 1959 Pseudosageceras curvatum; Chao, p. 185, pl. 1, figs. 13, 14, text-fig. 5a.

? 1959 Pseudosageceras multilobatum var. nov.; Jeannet, p. 30, pl. 6, fig. 1.

1961 Pseudosageceras schamarense; Kiparisova, p. 31, pl. 7, fig. 3.

1961 Pseudosageceras multilobatum var. gigantea; Popov, p. 13, pl. 2, figs. 1, 2.

non 1962 Pseudosageceras multilobatum; Kummel and Steele, p. 701, pl. 102, figs. 1, 2.

? 1966 Pseudosageceras multilobatum; Hada, p. 112, pl. 4, fig. 6.

? 1968 Pseudosageceras multilobatum; Kummel and Erben, p. 112, pl. 19, fig. 9.

1968 Pseudosageceras multilobatum; Shevyrev, p. 791, pl. 1, figs. 1, 2.

? 1973 Pseudosageceras multilobatum; Collignon, p. 5, pl. 1, fig. 1.

1978 Pseudosageceras multilobatum; Weitschat and Lehmann, p. 95, pl. 10, figs. 2ab.

1984 Pseudosageceras multilobatum; Vu Khuc, p. 26, pl. 1, fig. 1.

1994 Pseudosageceras multilobatum; Tozer, p. 83, pl. 18, figs. 1a, b; p. 384, fig. 17.

v 2008 Pseudosageceras multilobatum; Brayard and Bucher, p. 70, pl. 37, figs. 1–5.

v 2010 Pseudosageceras multilobatum; Stephen et al., figs. 6c, d, h.

v 2010b Pseudosageceras multilobatum; Brühwiler et al., p. 429, fig. 16(14).

v 2012a Pseudosageceras multilobatum; Brühwiler and Bucher, p. 47, pl. 26, fig. 4.

v 2012c Pseudosageceras multilobatum; Brühwiler and Bucher, p. 109, figs. 95A–N.

Occurrence Long-ranging cosmopolitan species, but extremely rare in all studied sections (only one measurable complete specimen). Common in northeastern Nevada and southeastern Idaho.

Description See, e.g., Brayard and Bucher (2008) for a thorough description. Involute oxyconic shell with an occluded umbilicus. Venter extremely narrow and bicarinate. Flanks weakly convex. Surface smooth without ornamentation. Suture line complex, typical of Hedenstroemiidae with several adventitious lobes and a characteristic trifid lateral lobe. Others lobes are bifid.

Measurements See Fig. 78. Estimated maximum size: ~15 cm.

Fig. 78
figure78

Scatter diagrams of H, W and U, and H/D, W/D and U/D for Pseudosageceras multilobatum (open symbols indicate the one measurable specimen from the Pahvant Range, Owenites beds; grey symbols indicate specimens from Siberia, Guangxi, Nevada, Madagascar, the Caucasus, Pakistan, Tibet and Oman; data from Dagys and Ermakova 1990, Brayard and Bucher 2008, Kummel and Steele 1962, Collignon 1933, Shevyrev 1968, Brühwiler et al. 2010b, 2012a, c; [n = 55])

Discussion Species typical for hedenstroemiids. Easily recognizable by its compressed and involute oxyconic shell, as well as its complex suture line architecture.

Genus Hedenstroemia Waagen, 1895

Type species Ceratites hedenstroemi Keyserling, 1845

Hedenstroemia kossmati Hyatt and Smith, 1905

Fig. 79a–f

Fig. 79
figure79

Hedenstroemia kossmati Hyatt and Smith 1905. All from the Owenites beds, Smithian; a, b UBGD 275141, loc. DH1-11, Confusion Range; c, d UBGD 275142, loc. DV2-7, Pahvant Range; d scale bar is 5 mm (H = 35 mm); e, f UBGD 275143, loc. DV2-7, Pahvant Range

1905 Hedenstroemia kossmati; Hyatt and Smith, p. 101, pl. 67, figs. 3–7; pl. 84, figs. 1–10.

1932 Hedenstroemia kossmati; Smith, p. 78, pl. 28, figs. 11–16; pl. 41, figs. 1–10; pl. 67, figs. 3–7.

1932 Hedenstroemia hyatti; Smith, p. 78, pl. 27, figs. 13–18.

v. 2010 Proptychitid gen. et sp. indet.; Stephen et al., fig. 4g, h, i.

Occurrence Fairly common in Owenites beds and rare in the Inyoites beaverensis sp. nov. beds in the Confusion Range [DH1-11, DH1-9, DH1-4/5, “Gastropod shales 2”], the Pahvant Range [n = 2; DV1-7] and the Torrey area [n = 1; FFA2]. Not documented from the other studied sections.

Description Very involute, compressed shell presenting a sulcate venter at all growth stages. Ventral margins bluntly angular. Flanks convex with maximum thickness at mid-flank. Umbilicus very narrow with broadly rounded shoulders forming a rather deep funnel. Surface apparently smooth, but very small plications and growth lines are visible near the umbilicus of one specimen. Complex ceratitic suture line, typical of hedenstromiids with an adventious element and a well-developed auxiliary series bending towards the umbilicus.

Measurements See Table 1. Estimated maximum size: ~20 cm.

Discussion H. kossmati differs from the type species by its sulcate venter at all growth stages and also by its suture line, which shows a slightly more complex auxiliary series. As already discussed by Hyatt and Smith (1905) and Smith (1932), this species appears to be nearly identical to H. mojsisovicsi Diener (1897), showing the same overall shape and complex architecture of the suture line. H. mojsisovicsi apparently can be distinguished only by its tabulate venter, according to Spath (1934) who assigned it a new generic and species name (Anahedenstroemia himalayica). However, Diener (1897) described the holotype of H. mojsisovicsi with “a flattened siphonal part, bordered on both sides by distinct marginal edges” (p. 63), thus suggesting persuasively that its venter was probably sulcate as observed for H. kossmati. Unfortunately, Diener (1897) did not illustrate the venter of his specimen or any additional material. In summary, H. kossmati is very likely conspecific with H. mojsisovicsi, and thus a junior synonym. However, the scarcity of data regarding H. mojsisovicsi from Spiti prevents a definitive merging of the two species. As Smith (1932) concluded, it is better to keep them separated. Without clearly visible suture lines or an exposed umbilicus, specimens of H. kossmati can be easily confused with Meekoceras gracilitatis. Another problem is that both taxa can occur within the same bed.

Noetling (1905; pl. 27, fig. 4) illustrated a specimen of H. mojsisovicsi from the Salt Range showing a marked egression at large size. Based on this specimen and this peculiar feature, Spath (1934) erected a new species, H. evoluta. Brühwiler et al. (2012c) recently illustrated additional specimens of H. evoluta from the Salt Range, confirming the strong egressive coiling of this species at large size.

Kummel (in Arkell et al. 1957) erected a new genus name (Pseudohedenstroemia) for H. kossmati based mainly on the tabulate aspect of its venter, compared to the type species, which shows a more acute to rounded venter at large size. However, since the type species presents a tabulate venter during early ontogenetic stages, and its suture line architecture and ornamentation are similar, we conclude that Kummel’s erection of Pseudohedenstroemia was not justified.

Hedenstroemiidae gen. indet. A

Fig. 80a, b

Fig. 80
figure80

a, b Hedenstroemiidae gen. indet. A. UBGD 275144, loc. MIA11, Mineral Mountains, Xenoceltitidae gen. indet. A beds, Smithian

Occurrence Rare in the Mineral Mountains, Xenoceltitidae gen. indet. A beds [n = 2; MIA11]. Not documented from the other studied sections.

Description Sampled specimens are all very poorly preserved, but coiling appears involute with a narrow, tabulate venter and almost angular ventral shoulders. Flanks probably slightly convex. Umbilicus apparently closed. Ornamentation and suture line not preserved.

Measurements Not possible due to poor preservation. Estimated maximum size: ~5 cm.

Discussion The poor preservation of our specimens precludes a taxonomic assignment. However, they more or less resemble latest Smithian Pseudosageceras species such as P. augustum from South China, Oman or Crittenden Springs (e.g., Brayard and Bucher 2008; Brühwiler et al. 2012a; Jenks et al. 2010). Another indirect indication of affiliation with the hedenstroemiid group is its stratigraphic position above the Anasibirites kingianus beds, which elsewhere corresponds to the Glyptophiceras sinuatum beds and its xenoceltitid fauna co-occurring with P. augustum.

Family Aspenitidae Spath, 1934

Genus Aspenites Hyatt and Smith, 1905

Type species Aspenites acutus Hyatt and Smith, 1905

Aspenites acutus Hyatt and Smith, 1905

Fig. 81a–j

Fig. 81
figure81

Aspenites acutus Hyatt and Smith 1905. a UBGD 275145, loc. DH1-11, Confusion Range, Owenites beds, Inyoites oweni horizons, Smithian; bd UBGD 275146, loc. DV1-9, Pahvant Range, Owenites beds, Inyoites oweni horizons, Smithian; eg UBGD 275147, loc. DH1-5, Confusion Range, Inyoites beaverensis sp. nov. beds, Smithian; hj UBGD 275148, loc. DH1-5, Confusion Range, Inyoites beaverensis sp. nov. beds, Smithian; h scale bar is 5 mm (estimated H = 24 mm)

1905 Aspenites acutus; Hyatt and Smith, 1905, p. 96, pl. 2, figs. 9-13; pl. 3, figs. 1–5.

? 1909 Hedenstroemia acuta; Krafft and Diener, p. 157, pl. 9, fig. 2.

1922 Aspenites acutus; Welter, p. 98, fig. 7.

1922 Aspenites laevis; Welter, p. 99, pl. 1, figs. 4, 5.

1932 Aspenites acutus; Smith, p. 86, pl. 2, figs. 9–13, pl. 3, figs. 1–5, pl. 30, figs. 1–26, pl. 60, figs. 4–6.

1932 Aspenites laevis; Smith, p. 86, pl. 28, figs. 28–33.

1932 Aspenites obtusus; Smith, p. 86, pl. 31, figs. 8–10.

1934 Aspenites acutus; Spath, p. 229, fig. 76.

? 1934 Parahedenstroemia acuta; Spath, p. 221, fig. 70.

1957 Aspenites acutus; Kummel, p. L142, fig. 173a–c.

1959 Aspenites acutus; Chao, p. 269, pl. 35, figs. 12–18, 23, text-fig. 34a.

1959 Aspenites laevis; Chao, p. 270, pl. 35, figs. 9–11, text-fig. 34b.

1962 Aspenites acutus; Kummel and Steele, p. 692, pl. 99, figs. 16–17.

1962 Hemiaspenites obtusus; Kummel and Steele, p. 666, pl. 99, fig. 18.

1979 Aspenites cf. acutus; Nichols and Silberling, pl. 1, figs. 10–11.

1979 Aspenites acutus; Nichols and Silberling, pl. 1, figs. 12–14.

v 2008 Aspenites acutus; Brayard and Bucher, p. 77, pl. 42, figs. 1–9.

2010 Aspenites acutus; Stephen et al., fig. 4f.

2010b Aspenites acutus; Brühwiler et al., p. 429, fig. 16(12, 13).

2012a Aspenites acutus; Brühwiler and Bucher, p. 48, pl. 26, figs. 1, 2.

2012b Aspenites acutus; Brühwiler et al., p. 164, figs. 41A-M.

Occurrence Relatively rare in the Confusion Range, Pahvant Range and the Mineral Mountains (one measurable specimen), documented from the Owenites beds. Absent from all other studied sections. Commonly found in northeastern Nevada and southeastern Idaho. Intertropical widely distributed species (e.g., South China, Oman, Tibet).

Description Involute, very compressed oxyconic shell with slightly convex flanks and an occluded umbilicus. Maximum curvature at mid-flank. Venter with a characteristic acute keel. Umbilical region slightly depressed. Ventral shoulders may be more pronounced on some specimens. Surface nearly smooth except for fine radial folds and falcoid growth lines. Suture line basically ceratitic, but more complex with a wide curved series of small auxiliary saddles.

Measurements See Fig. 82. Estimated maximum size: ~8 cm.

Fig. 82
figure82

Scatter diagrams of H, W and U, and H/D, W/D and U/D for Aspenites acutus (open symbols indicate the one measurable specimen from the Pahvant Range, Owenites beds; grey symbols indicate specimens from Guangxi, Nevada, Spiti, Tibet and Oman; data respectively from Brayard and Bucher 2008, Kummel and Steele 1962 and Brühwiler et al. 2010b, 2012a, b; [n = 55])

Discussion Reader should refer to Brayard and Bucher (2008) for an in-depth systematic review and discussion of this species. A. acutus mainly differs from other aspenitid taxa (e.g., Pseudaspenites layeriformis) by its occluded umbilicus (see also Brayard and Bucher 2008 for a thorough comparison). Only Parahedenstroemia acuta (Spath 1934) from Spiti, which Spath erected based on Hedenstroemia acuta (Krafft and Diener 1909) as the type species, is morphologically compatible with A. acutus. However, it appears that the suture line of this taxon is simpler. Additional material is needed to determine whether it should be placed within the Aspenites genus.

Family Incertae sedis

Genus gen. indet. A

Fig. 83a–t

Fig. 83
figure83

Gen. indet. A. All from the loc. “Gastropod shales 2”, Confusion Range, Smithian; a, b UBGD 275149; ce UBGD 275150; f, g UBGD 275151; g scale bar is 5 mm (H = 6 mm); hj UBGD 275152; km UBGD 275153; n, o UBGD 275154; pr UBGD 275155; s, t UBGD 275156

Occurrence Very abundant in the Confusion Range, “Gastropod shales 2”. Not found in other studied sections.

Description Small size specimens with a moderately evolute and compressed shell and a rounded venter. Flanks slightly convex with maximum curvature at two-thirds of the flank from the umbilicus. Umbilicus relatively shallow with an apparent perpendicular wall and rounded shoulders. Surface ornamented with variable strength, sinuous folds crossing the venter. On some specimens, a delicate strigation is also visible near the venter. Suture line ceratitic.

Measurements See Table 1. Estimated maximum size: ~4 cm.

Genus gen. indet. B

Fig. 84a–i

Fig. 84
figure84

Gen. indet. B. All from the loc. “Gastropod shales 2”, Confusion Range, Smithian; a, b UBGD 275157; ce UBGD 275158; f, g UBGD 275159; h, i UBGD 275160

Occurrence Common in the Confusion Range, “Gastropod shales 2”. Not found in other studied sections.

Description Overall shell shape similar to Gen. indet. A, but with a tabulate venter. Flanks are also more convex with maximum curvature at one-third of the flank from the umbilicus. Umbilicus relatively shallow with well-rounded shoulders. Surface ornamented with very rare folds, which apparently do not cross the venter. Suture line ceratitic.

Measurements See Table 1. Estimated maximum size: ~3.5 cm.

Genus gen. indet. C

Fig. 85a, b

Fig. 85
figure85

a, b Gen. indet. C. UBGD 275161, loc. DH1-12, Confusion Range, Owenites beds, Inyoites oweni horizons, Smithian

Occurrence One specimen found in the Confusion Range, Owenites beds, top of the Inyoites oweni horizons [DH1-12]. Not found in other studied sections.

Description Involute and compressed shell with a tabulate venter. Ventral shoulders angular. Flanks convex with maximum curvature near mid-flank. Umbilicus very narrow with broad rounded shoulders. Surface ornamented with radial ribs fading near the ventral shoulders. Suture line fragmentary, but ceratitic.

Measurements See Table 1.

Genus gen. indet. D

Fig. 86a–c

Fig. 86
figure86

ac Gen. indet. D. UBGD 275162, loc. DV2-200, Pahvant Range, Meekoceras olivieri sp. nov. beds, Smithian; c scale bar is 5 mm (H = 15.1 mm)

Occurrence One specimen found in the Pahvant Range, Meekoceras olivieri sp. nov. beds. Not found in other studied sections.

Description Moderately involute and compressed shell. Venter narrowly rounded. Flanks convex with maximum curvature at one-third of the flank from the umbilicus. Umbilicus relatively shallow with a prominently oblique wall and well-rounded shoulders. Surface apparently smooth. Suture line partly known with deep, well-indented lobes and elongated, pinched saddles.

Measurements See Table 1.

Discussion The suture line as well as the overall compressed shape of this specimen is similar to some flemingitids. However, the prominently inclined umbilical wall is not characteristic of flemingitids and may indicate that it belongs to another family.

Genus gen. indet. E

Fig. 87

Fig. 87
figure87

Gen. indet. E. UBGD 275163, loc. DV2-5, Pahvant Range, Flemingites sp. indet. beds, Smithian

Occurrence One specimen found in the Pahvant Range, Flemingites sp. indet. bed. Not found in other studied sections.

Description Moderately involute and compressed shell with an apparent narrowly arched venter. Flanks slightly convex with maximum curvature at one-third of the flank from the umbilicus. Umbilicus appears rather deep with an inclined wall and large rounded shoulders. Surface ornamented with variable strength, radial ribs, folds and growth lines. Large ribs fade near mid-flank toward venter. Growth lines reach the venter. Suture line unknown.

Measurements Not possible.

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Acknowledgments

This work is a contribution to the team BioME of the UMR CNRS 6282 and to the teams “Paleoenvironments” and “Biodiversity” of the UMR CNRS 5276; it was funded by the Région Bourgogne, the FRB, and the CNRS INSU Interrvie. All fossil localities mentioned in this report are located on US public land under the stewardship of the Bureau of Land Management (BLM) of the US Department of the Interior and the US Forest Service (Fishlake National Forest) of the US Department of Agriculture; their management and access to these lands is much appreciated. C. Monnet (Lille) and an anonymous reviewer provided constructive suggestions that helped us to improve the manuscript. D. Snyder is thanked for help in the field. N. Goudemand and R. Hofmann (Zurich) kindly determined conodonts and bivalves, respectively. We also acknowledge numerous stimulating discussions with Hugo Bucher (Zurich) regarding Smithian ammonoids and biostratigraphy over the past years.

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Correspondence to Arnaud Brayard.

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Brayard, A., Bylund, K.G., Jenks, J.F. et al. Smithian ammonoid faunas from Utah: implications for Early Triassic biostratigraphy, correlation and basinal paleogeography. Swiss J Palaeontol 132, 141–219 (2013). https://doi.org/10.1007/s13358-013-0058-y

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Keywords

  • Ammonoids
  • Early Triassic
  • Smithian
  • Utah
  • Biostratigraphy
  • Paleogeography
  • New genus and species