A proposed terminology for the dentition of gomphodont cynodonts and dental morphology in Diademodontidae and Trirachodontidae

HENDRICKX, CHRISTOPHE; ABDALA, FERNANDO; CHOINIERE, JONAH N.

PeerJ

PeerJ

Año: 2019 vol. 7

Gomphodont cynodonts were close relatives of mammals and one of the Mesozoiclineages of cynodont therapsids that became extinct at the end of the Triassic.Gomphodonts were omnivorous to herbivorous animals characterized bylabiolingually expanded postcanines, which allowed tooth-to-tooth occlusion.The morphology of the upper and lower postcanines presents important meansof distinguishing among major lineages within Gomphodontia, that is,Diademodontidae, Trirachodontidae, and Traversodontidae, but the dentition ofmost Diademodontidae and Trirachodontidae remain poorly documented.Here, we present a comprehensive description of the dentition of eachdiademodontid and trirachodontid species, as well as detailed illustrations of eachdental unit, after firsthand examination of material and 3D reconstructions ofpostcanine teeth. Based on dental morphology, Trirachodon berryi and?Trirachodon kannemeyeri,? considered as separate taxa by some authors are hereinterpreted as representing different ontogenetic stages of the same species.Likewise, Sinognathus and Beishanodon, thought to belong to non-cynognathiancynodonts and traversodontids by some authors, are referred to Trirachodontidaeand Gomphodontia based on dental characters, respectively. Finally, we proposea standardized list of terms and abbreviations for incisors, canines, andpostcanines anatomical entities, with the goal of facilitating future descriptionsand communication between researchers studying the gomphodont dentition.