An illustrated atlas of the vertebral morphology of extant non-caenophidian snakes, with special emphasis on the cloacal and caudal portions of the column Author Szyndlar, Zbigniew Institute of Systematics and Evolution of Animals, Polish Academy of Sciences, Slawkowska 17, 31 - 016 Krakow, Poland Author Georgalis, Georgios L. https://orcid.org/0000-0001-7759-6146 Institute of Systematics and Evolution of Animals, Polish Academy of Sciences, Slawkowska 17, 31 - 016 Krakow, Poland dimetrodon82@gmail.com text Vertebrate Zoology 2023 2023-09-27 73 717 886 http://dx.doi.org/10.3897/vz.73.e101372 journal article http://dx.doi.org/10.3897/vz.73.e101372 2625-8498-73-717 8F3D5EDA2F184E5CA53E2F7741FF1339 318B657A15AB5708B3C35FC1A82B4945 Amerophidia Vidal, Delmas & Hedges, 2007 General information. Amerophidia constitute a recently established group based on molecular phylogenies ( Vidal et al. 2007 ). It consists of Aniliidae and Tropidophiidae and is thought to represent the most basal group of alethinophidians ( Scanlon and Lee 2011 ). As their name attests, amerophidians are currently distributed in the Americas. Despite the strong molecular evidence supporting its monophyly (e.g., Vidal et al. 2007 , 2010 ; Wiens et al. 2008 ; Pyron and Burbrink 2012 ; Streicher and Wiens 2016 ; Zheng and Wiens 2016 ; Burbrink et al. 2020 ; Ortega-Andrade et al. 2022 ), amerophidian apomorphic morphological characters are mostly lacking, with the exception of a few cranial features shared among aniliids and tropidophiids, primarily in the shape of their palate, but also a soft anatomical apomorphy, an oviduct connecting to the diverticuli of the cloaca, instead of connecting directly to the cloaca ( Maisano and Rieppel 2007 ; Scanlon and Lee 2011 ; Siegel et al. 2011 ; Hsiang et al. 2015 ). Indeed, morphology-based phylogenies have failed to recover such close relationship among Aniliidae and Tropidophiidae (e.g., Gauthier et al. 2012 ; Scanferla et al. 2016 ; Smith and Scanferla 2021 ). This is also true for their vertebral morphology, which is rather different between aniliids and tropidophiids.