Butt heads like deer? Further to Oldest animal sperm to date, from ScienceDaily:
“It is incredible to think that features found in deer such as the water deer, musk deer and muntjacs today were already represented 270 million years ago,” says Cisneros.
The researchers found the Tiarajudens’ marginal teeth are also located in a bone from the palate called epipterygoid. “This is an extraordinary condition as no other animal in the lineage leading to mammals show marginal dentition in a bone from the palate,” says Abdala.
In another group of mammal fossil relatives, dinocephalians — that lived at the same time as anomodonts, some of the bones in their foreheads were massively thickened. This can be interpreted as being used in head-butting combat, a modern behaviour displayed by several deer species today.
“Fossils are always surprising us. Now they show us unexpectedly that 270 million years ago two forms of interspecific combat represented in deer today, were already present in the forerunners of mammals,” says Cisneros.
File under: Stasis File with: Everything new is old again.
Here’s the abstract:
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 assembled. Open access – Juan Carlos Cisneros, Fernando Abdala, Tea Jashashvili, Ana de Oliveira Bueno, Paula Dentzien-Dias. Tiarajudens eccentricusandAnomocephalus africanus, two bizarre anomodonts (Synapsida, Therapsida) with dental occlusion from the Permian of Gondwana. Royal Society Open Science, 2015; 2 (7): 150090 DOI: 10.1098/rsos.150090
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