Tiarajudens eccentricus and Anomocephalus africanus, two bizarre anomodonts (Synapsida, Therapsida) with dental occlusion from the Permian of Gondwana.

CISNEROS, J. C.; ABDALA, V.; JASHASHVILI, T.; OLIVEIRA BUENO, A.; DENTZIEN-DIAS, P. C.

Royal Society Open Science

The Royal Society Publishing

Año: 2015

2054-5703

Anomodontia was a highly successful tetrapod clade duringthe Permian and the Triassic. New morphological informationregarding two bizarre basal anomodonts is provided and theirpalaeoecological significance is explored. The osteology of therecently discovered Tiarajudens eccentricus Cisneros et al. 2011,from the Brazilian Permian, is described in detail. The taxonexhibits unusual postcranial features, including the presence ofgastralia. Additional preparation and computed tomographyscans of the holotype of Anomocephalus africanus Modestoet al. 1999 discovered in the Karoo Basin of South Africaallow a reappraisal of this genus. Anomocephalus is similar toTiarajudens with regard to several traits, including a batteryof large, transversally expanded, palatal teeth. Molariformteeth are present in the mandible of the African taxon,providing additional insight into the function of the earliesttooth-occlusion mechanism known in therapsids. At least twowaves of tooth replacement can be recognized in the palateof Anomocephalus. The outsized, blade-like caniniforms of theherbivorous Tiarajudens allow several non-exclusive ecologicalinterpretations, amongwhich we favour intraspecific display orcombat. This behaviour was an alternative to the head-buttingpractised by the contemporary dinocephalians. Combat specializations that are considered typical ofCenozoic herbivores likely evolved during the Middle Permian, at the time the first communities withdiverse, abundant tetrapod herbivores were being assembled.