The unique dentition of the rhynchocephalian Clevosaurus brasiliensis, and rhynchocephalian diversity in the Late Triassic of the southern hemisphere.

BENTON, MIKE; CHAMBI-TROWELL, SOPHIE; MARTINELLI, AGUSTÍN G.; WHITESIDE, DAVID I.; RAYFIELD, EMILY J.

Congreso; he Palaeontological Association 64th Annual Meeting, Virtual meeting; 2020

Oxford University

Rhynchocephalia is an order of lizard-like reptiles that frst appeared in the fossil recordduring the Triassic. Most of the oldest known taxa are the derived acrodont-toothedSphenodontia. Clevosaurus brasiliensis is one of several sphenodontians known fromthe Late Triassic (Norian) of South America; these are some of the oldest sphenodontiansknown. Here we describe the CT scanning of three exceptionally-preserved skulls,revealing Clevosaurus brasiliensis to have a unique form of acrodonty with much of eachindividual tooth being encased within the jaw bones. In addition, we address the knownrhynchocephalian diversity from the Late Triassic of South America and in particular wepresent new material for an as yet undescribed stem sphenodontian rhynchocephalian; thissignifcantly enhances our understanding of the early evolution of rhynchocephalians.