Morphological Diversity of the External Shell Sculpture of Paleozoic Cephalopods: How Did It Arise and What Does It Mean?
The sculpture of the external shell of cephalopods, along with the shell shape, is one of the most characteristic morphological features. Sometimes (especially in the English-language literature) this shell characteristic is referred to as ornamentation, but for our purposes, because of the state of preservation of fossils, it makes sense to distinguish between the concepts of “sculpture” and “ornamentation,” although, they are both certainly elements of the ornament of the shell. Under the term sculpture I include the convexities and concavities on the shell, which embrace all the shell layers and are expressed on the internal mold. By ornamentation I mean smaller irregularities on the shell surface, which are expressed only in the external shell layer and are not reflected on the internal mold. Characters of the outer ornament are important, most often crucial, both for the knowledge of the biological diversity of this group of mollusks (for their systematics), and for...
Keywords:Cephalopoda shell sculpture Paleozoic
The study was carried out within the framework of program no. 17 of the fundamental research of the Presidium of the Russian Academy of Sciences “Evolution of the organic world. The role and influence of planetary processes” (subprogram 1. “Development of life and biosphere processes”), the project “Turnovers of the morphological and ecological structure of pelagic communities at the critical boundaries of the Phanerozoic,” the state budget theme of the Geological Faculty of the Moscow State University “Stratigraphic and paleontological characteristics of the Phanerozoic and Late Proterozoic deposits of Russia and adjacent territories.”
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