Taxonomic revision of the snakes of the genera Palaeopython and Paleryx (Serpentes, Constrictores) from the Paleogene of Europe

Abstract Large constrictor snakes, referred to the genera Palaeopython and Paleryx , are an ecologically prominent part of fauna Europe during Paleogene. Most species were named over a century ago their taxonomy is largely based on isolated vertebrae. Furthermore, majority taxa originate from imprecisely known localities within Phosphorites du Quercy, in southern France, thus exact age not known. We critically review re-diagnose these personal examination all existing type material, array new specimens, detailed literature review. consider be valid propose vertebral characters distinguish them. recognize three i.e. cadurcensis (type species) ceciliensis Geiseltal, helveticus Dielsdorf (Switzerland), one rhombifer Hordle Cliff (England). Four other species, which previously treated as members “ ” filholii neglectus fischeri Messel, spinifer also considered but pertain genera. Among four taxa, has been recently assigned its own genus, Eoconstrictor . A Phosphoroboa gen. nov. established accommodate designate lectotype for establish that paralectotype maxilla dentary reasonably this species. New material attributed described old collections Quercy. cayluxi another synonymized here with further clarify important errors original description figures identify specimens comprise series, lectotype. Much area Geiseltal intracolumnar variation considered. describe additional cranial Cliff. Based we suggest non-booid affinities rhombifer. depressus agree previous suggested synonymy re-describe paralectotypes refer paying special attention variation; defer decision generic relations until more abundant complete can studied. booid cf. Geiseltal; similar was only Messel Dielsdorf. determine contains two distinct unrelated nominotype. certain issues regarding series lectotype, report unrecognized associated latter specimen; transfer features recombine it comb. finally much Quercy (both late Eocene Escamps C), variation. Escamps, booid. An analytical approach undertaken many remains order quantify structures assess variation, well associating elements vertebral-based taxa. 3D models presented. The importance vertebrae fossil Constrictores addressed, although acknowledged afford most reliable phylogenetic conclusions. diversity, distribution, biogeographic origins, final demise extinction large Paleogene discussed.