Eocene constrictors (Serpentes; Alethinophidia) from western India: New taxonomic and paleobiogeographic insights

The Eocene fossiliferous horizons of western India are known for a remarkably diverse vertebrate fauna, including archaic mammals, squamates, and reptiles, which provide significant insights into the biogeographic history of the subcontinent. Here, we report new fossil snakes attributable to Constrictores Oppel, 1811 from the early Eocene (Ypresian, ~55 Ma) of Cambay Basin, Surat District, and the middle Eocene (Lutetian, ~47 Ma) horizons at Panandhro, Kutch District, Gujarat State, western India. Morphological comparison with previously described Indian fossil constrictors suggests that the material presented here not only supplements the existing record but may possibly represent new taxa. Size estimations reveal marked differences in body length between the Cambay Shale and Panandhro constrictors, which may reflect ecological and environmental differences between the two depositional settings. Biogeographic considerations suggest that the Indian Eocene constrictors likely represent immigrant lineages that possibly migrated into the subcontinent from Europe or Asia at the time of India-Asia collision (~55 Ma).