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Dental occlusion and head combat in Permian anomodonts Tiarajudens and Anomocephalus (free pdf)

Ben Creisler

A new paper in open access:

Juan Carlos Cisneros, Fernando Abdala, Tea Jashashvili, Ana de
Oliveira Bueno, Paula Dentzien-Dias (2015)
Tiarajudens eccentricus and Anomocephalus africanus, two bizarre
anomodonts (Synapsida, Therapsida) with dental occlusion from the
Permian of Gondwana.
Royal Society Open Science 2:150090
DOI: 10.1098/rsos.150090

Anomodontia was a highly successful tetrapod clade during the Permian
and the Triassic. New morphological information regarding two bizarre
basal anomodonts is provided and their palaeoecological significance
is explored. The osteology of the recently discovered Tiarajudens
eccentricus Cisneros et al. 2011, from the Brazilian Permian, is
described in detail. The taxon exhibits unusual postcranial features,
including the presence of gastralia. Additional preparation and
computed tomography scans of the holotype of Anomocephalus africanus
Modesto et al. 1999 discovered in the Karoo Basin of South Africa
allow a reappraisal of this genus. Anomocephalus is similar to
Tiarajudens with regard to several traits, including a battery of
large, transversally expanded, palatal teeth. Molariform teeth are
present in the mandible of the African taxon, providing additional
insight into the function of the earliest tooth-occlusion mechanism
known in therapsids. At least two waves of tooth replacement can be
recognized in the palate of Anomocephalus. The outsized, blade-like
caniniforms of the herbivorous Tiarajudens allow several non-exclusive
ecological interpretations, among which we favour intraspecific
display or combat. This behaviour was an alternative to the
head-butting practised by the contemporary dinocephalians. Combat
specializations that are considered typical of Cenozoic herbivores
likely evolved during the Middle Permian, at the time the first
communities with diverse, abundant tetrapod herbivores were being