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Dryad

Data Matrices Nukukammophis

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Jun 17, 2021 version files 23.49 MB

Abstract

Reassessment of the anatomy of a three-dimensionally preserved, partial braincase from the Lower Cretaceous (lower Valanginian; ~139 mya) Kirkwood Formation of the Kirkwood Cliffs Quarry, South Africa, reveals it to be that of a new fossil snake species. The braincase presents a number of squamate skull features but also specific braincase features shared with early snakes such as Najash, Dinilysia, Sanajeh, and Menarana (e.g., presence of a large fenestra ovalis; fenestra rotunda separated from fenestra ovalis by prominent crista interfenestralis; reduced basal tubera on basioccipital). Phylogenetic relationships were analyzed using two distinct data sets and under different optimality criteria, recovering this new snake as an early-evolving lineage with close affinities to other Cretaceous Gondwanan snakes including Najash, Dinilysia, and other typical madtsoiids. This three-dimensionally preserved braincase reveals important aspects of early snake cranial evolution that were previously unknown from the oldest known fossil snakes. This specimen extends the fossil record of Gondwanan snakes by at least 45 my, making it the oldest known African and Gondwanan fossil snake and supporting a much broader palaeobiogeographical distribution of early snakes across ancient Gondwanan continents during the Early Cretaceous.