HYRACODONTIDAE, Cope, 1879

Veine-Tonizzo, Léa, Tissier, Jérémy, Bukhsianidze, Maia, Vasilyan, Davit & Becker, Damien, 2023, Cranial morphology and phylogenetic relationships of Amynodontidae Scott & Osborn, 1883 (Perissodactyla, Rhinocerotoidea), Comptes Rendus Palevol 22 (8), pp. 109-142 : 121

“ HYRACODONTIDAE ”

Teletaceras radinskyi Hanson, 1989 is placed as an early-diverging rhinocerotoid and as a sister taxon to the clade including the Eggysodontidae , the Paraceratheriidae and the Amynodontidae . The monophyly of Eggysodontidae is supported by five unambiguous synapomorphies: protocone and hypocone on P2 form a lingual bridge 94 (1); the hypocone is anterior to metacone on P3-4 103 (2); M3 ectoloph and metaloph are fused (ectometaloph) 133 (1); navicular cross section is rectangle 268 (1); lower canines are strong 284 (2). The clade has a Bremer index = 2. Eggysodontidae are sister group of the clade formed by Hyracodon nebraskensis Leidy, 1850 , Paraceratheriidae and Amynodontidae . Hyracodon nebraskensis is a sister taxon to Paraceratheriidae and Amynodontidae . Three unambiguous synapomorphies support the monophyly of Paraceratheriidae : nearly horizontal symphysis 53 (2); M3 ectoloph and metaloph are fused (ectometaloph) 133 (1); atlas axis-facets are transversally concave 187 (2) and it is weakly supported (Bremer index = 1).