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Journal of Iberian Geology

, Volume 45, Issue 2, pp 269–286 | Cite as

Cranial anatomy of the Early Triassic trematosaurine Angusaurus (Temnospondyli: Stereospondyli): 3D endocranial insights and phylogenetic implications

  • Meritxell Fernández-Coll
  • Thomas Arbez
  • Federico Bernardini
  • Josep FortunyEmail author
Research Paper

Abstract

Background

Trematosaurines are a widespread group of early tetrapods (Temnospondyli, Stereospondyli) known from all continents except South America and Antarctica. They radiated rapidly during the Early Triassic just after the End Permian mass extinction and are of interest to understand the recovery of the ecosystems just after extinction. Trematosaurines disappeared during the Late Triassic.

Objective

Herein, a re-description of the genus Angusaurus is presented based on a new specimen. This genus is known from the Early Olenekian (Early Triassic) of Russia and comprises four valid species, although the diagnostic characters that deine some of them are vague and controversial.

Methods

The new specimen described, using MicroCT scanner and 3D digital modeling, sheds light on the anatomical details of the external and inner cranial structure, and provides new details of the neurocranium as well as the ontogeny of this genus.

Results and Discussion

A cladistic analysis of trematosaurines (including most trematosauroids) confirms the problematic nature of some Angusaurus species and provides a basis for detailed discussion about the phylogeny of trematosaurines.

Keywords

Trematosauria Trematosauroidea Trematosauridae Trematosaurinae Stereospondyli 

Resumen

Antecedentes

Los trematosaurinos son un grupo ampliamente distribuido de tetrápodos basales (Temnospondyli, Stereospondyli) conocidos de todos los continentes excepto Sud América y la Antártida. Este grupo se diversificó rápidamente durante el Triásico Inferior justo después de la extinción en masa del Pérmico terminal y son de interés para entender la recuperación de los ecosistemas justo después de la extinción. Los trematosaurinos desaparecieron durante el final del Triásico.

Objetivo

En el presente trabajo se presenta una re-descripción del genero Angusaurus basada en un nuevo espécimen. Este género es conocido del Olenekiense Inferior (Triásico Inferior) de Rusia y comprende cuatro especies validas, aunque los caracteres diagnósticos que definen algunos de ellos son vagos y controvertidos.

Métodos

El nuevo espécimen descrito, usando un escáner de MicroTomografía y modelado digital 3D, aporta nueva luz sobre detalles craneales anatómicos externos y de la estructura craneana interna y aporta nuevos detalles del neurocráneo así como de la ontogenia de este género.

Resultados y discusión

Un análisis cladístico de los trematosaurinos (incluyendo la mayoría de trematosauroideos) confirma la problemática naturaleza de las especies de Angusaurus y aporta las bases para una profunda discusión sobre la filogenia de los trematosaurinos.

Palabras clave

Trematosauria Trematosauroidea Trematosauridae Trematosaurinae Stereospondyli 

Notes

Acknowledgements

Our special thanks to Dr. Rainer Schoch (SMNS, Stuttgart) for the access and loan of the studied specimen and to Dr. Igor V. Novikov (PIN, Moscow) for providing photos and relevant data about Russian trematosaurids. Sergio Llacer is acknowledged for his help during segmentation process of the studied specimen and Montse Vilalta for assistance in some drawings. Judit Marigó proofread the paper and revised English grammar. J. Fortuny acknowledges the support of the postdoc Grant Agència de Gestió d’Ajuts Universitaris i de Recerca, “Beatriu de Pinós” 2014–BP-A 00048 from the Generalitat de Catalunya. This work received support from CERCA programme (Generalitat de Catalunya).

Supplementary material

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Supplementary material 1 (DOCX 16 kb)
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Copyright information

© Springer International Publishing AG, part of Springer Nature 2018

Authors and Affiliations

  1. 1.Faculty of Life and Environmental SciencesUniversity of IcelandReykjavíkIceland
  2. 2.Centre de Recherches sur la Paléobiodiversité et les Paléoenvironnements, UMR 7207 CNRS-MNHN-UPMCMuséum national d’Histoire naturelleParisFrance
  3. 3.Centro Fermi, Museo Storico della Fisica e Centro di Studi e Ricerche, ‘Enrico Fermi’RomeItaly
  4. 4.Multidisciplinary Laboratorythe ‘Abdus Salam’ International Centre for Theorethical PhysicsTriesteItaly
  5. 5.Institut Català de Paleontologia M. Crusafont, C\de les Columnes, s/nUniversitat Autònoma de BarcelonaCerdanyola del VallèsSpain

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