A Carboniferous synapsid with caniniform teeth and a reappraisal of mandibular size-shape heterodonty in the origin of mammals.

ABSTRACT: Heterodonty is a hallmark of early mammal evolution that originated among the non-mammalian therapsids by the Middle Permian. Nonetheless, the early evolution of heterodonty in basal synapsids is poorly understood, especially in the mandibular dentition. Here, we describe a new synapsid, Shashajaia bermani gen. et sp. nov., based on a well-preserved dentary and jaw fragments from the Carboniferous-Permian Halgaito Formation of southern Utah. Shashajaia shares with some sphenacodontids enlarged (canine-like) anterior dentary teeth, a dorsoventrally deep symphysis and low-crowned, subthecodont postcanines having festooned plicidentine. A phylogenetic analysis of 20 taxa and 154 characters places Shashajaia near the evolutionary divergence of Sphenacodontidae and Therapsi

SUBMITTER: Huttenlocker AK 

PROVIDER: S-EPMC8672069 | biostudies-literature | 2021 Dec

REPOSITORIES: biostudies-literature