The Diversity and Distribution of Palaeogene Snakes : A Review with Comments on Vertebral Sufficiency

We give a review of all published Palaeogene snake taxa from all localities worldwide. Several conceptual and material advances in the past two decades—a focus on apomo+P31rphies, greater attention to variation, quantification of morphology, and new fossil discoveries—have vivified the fossil record. Particularly noteworthy have been new fossils from Gondwanan continents and complete, articulated skeletons. Species known only from vertebrae are unlikely to be placed precisely phylogenetically, but a high number of vertebrae is a strong indication that cranial remains are present, which in turn allow more precise phylogenetic placement. Extrapolations of snake palaeodiversity are of the same order of magnitude as rough calculations of cumulative lineage diversity in the Palaeogene, raising the prospect that palaeontological morphospecies may more closely approximate biological species than is commonly conceived. As their interrelationships become better known, Palaeogene fossils will increasingly help elucidate the early evolution of snakes