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.