Print ISSN: 0031-0247
Online ISSN: 2274-0333
Werneburg et al. New Permian Caseid from France
Small sauropod tracks, Southern France
Hypoplasia: CT-scan or naked eye?
Dortokid turtle from Late Cretaceous of Cruzy
Eocene otoliths (Clinchfield Formation), Georgia
Eocene (56) , Quercy phosphorites (37) , systematics (31) , Rodents (29) , Mammalia (26)
The skull of Tetraceratops insignis (Synapsida, Sphenacodontia)
Frederik SpindlerKeywords: cranium; pelycosaur; Permian; therapsid origins
Tetraceratops insignis is known from a single, crushed skull from the Lower Permian of Texas. Its unique proportions and osteological details gained central meaning in the question of the origins of Therapsida since this early synapsid has been determined as the oldest and less derived therapsid. Apart from Tetraceratops, the ‘mammal-like’ Therapsida and their sister, the pelycosaur-grade Sphenacodontidae, are separated by one of the longest ghost lineages in tetrapod fossil record. However, the minor, though well justified critique faced insistent publication regarding the therapsid hypothesis. A carefull re-evaluation of the holotypic skull reveals that therapsid traits cannot be supported, including a rejection of the formerly supposed adductor shelf in the temporal fenestra. Increased understanding of ‘pelycosaur’ character variation underlines a haptodontine-grade or, less likely, sphenacodontid position for Tetraceratops.
Published in Vol 43-1 (2020)