The affinities of the late Triassic Cryptovaranoides and the age of Crown Squamates

Most living reptile diversity is concentrated in Squamata (lizards, including snakes), which have poorly known origins in space and time. Recently, †Cryptovaranoides microlanius from the Late Triassic of the United Kingdom was described as the oldest crown squamate. If true, this result would push back the origin of all major lizard clades by 30-65 million years and suggest that divergence times for reptile clades estimated using genomic and morphological data are grossly inaccurate. Here, we use CT scans and expanded phylogenetic datasets to re-evaluate the phylogenetic affinities of †Cryptovaranoides and other putative early squamates. We resolve †Cryptovaranoides as a member of the bird and crocodilian total clade, Archosauromorpha, in sharp contrast to its originally hypothesized affinities. Bayesian total evidence dating supports a Jurassic origin of crown squamates, not Triassic as recently suggested. We highlight how features traditionally linked to lepidosaurs are in fact widespread across Triassic reptiles, reaffirming the importance of critical morphological analysis for interpreting the fossil record and calibrating the Tree of Life.