Second specimen of Corriebaatar marywaltersae from the Lower Cretaceous of Australia confirms its multituberculate affinities

Abstract

A second specimen of the Australian cimolodontan multituberculate Corriebaatar marywaltersae from the same locality (Flat Rocks) as the holotype and previously only known specimen, reveals far more anatomical information about the species. The new specimen, composed of most of a dentary containing a complete p4 and alveoli for the lower incisor and the lower first and second molars, exhibits a suite of features consistent with allocation of Corriebaatar to Cimolodonta and further confirms the presence of multituberculates on Gondwana during the Mesozoic. The revised (older) age of the Flat Rocks locality to latest Barremian (mid-Early Cretaceous) establishes C. marywaltersae as the oldest currently known cimolodontan. This has profound biogeographic implications for the distribution of multituberculates on Gondwana as well as globally, particularly in light of the fact that Corriebaatar appears to be a relatively derived member of Cimolodonta.