A new Early Cretaceous tritylodontid (Synapsida, Cynodontia, Mammaliamorpha) from the Kuwajima Formation (Tetori Group) of central Japan
Matsuoka et al
We describe tritylodontid remains from the Lower Cretaceous Kuwajima Formation (Tetori Group) in central Japan as representing a new genus, Montirictus kuwajimaensis, gen. et sp. nov. Montirictus is a medium-sized tritylodontid genus characterized by upper cheek teeth having the cusp formula 2-2-2 with subequal cusps, buccal and lingual cusps retaining a crescentic shape with both buccal and lingual ridges anteriorly, and ‘V’-shaped buccolingual cross-sections of two anteroposterior grooves between the three cusp rows. Tentative dating of the Kuwajima Formation to the Barremian–Aptian makes it the stratigraphically youngest representative of a long-lived, globally distributed and abundant mammaliamorph lineage and extends the known geographic range of tritylodontids.