The Siwalik Group snake fauna includes eight diagnosable taxa consisting of Python sp, cf. Erycinae indeterminate, Acrochordus dehmi, Gansophis potwarensis gen. et sp. nov., the first fossil record of Bungarus, Natricinae indeterminate, Chotaophis padhriensis gen. et sp. nov., and Sivaophis downsi gen. et sp. nov, as well as Boidae? indeterminate, Elapidae? indeterminate, and two recognizable but unnamed morphotypes. The record is dominated by Acrochordus in terms of frequency of specimens, but demonstrates increasing taxonomic/morphotypic diversity starting between 10.0 and 9.0 mya that is concurrent with the inferred development of the Asian monsoonal system and the deposition of the Dhok Pathan Formation. These two events, driven by the uplift of the Tibetan Plateau, likely provided an increasing range of potential habitats for a greater diversity of taxa.
The Siwalik Group snake fauna was highly endemic, and exclusivity of Acrochordus, Bungarus, and new taxa described here to the Siwalik sequence suggests that partition of European and South Asian biogeographic theaters occurred no later than middle Miocene. The snake fauna of the Siwalik Group is markedly different from the extant fauna of the Potwar Plateau, with only Bungarus occurring in both. These differences are present at the youngest Siwalik snake localities indicating that the pronounced faunal changes occurred after 6.35 Ma, likely concurrent with the draining of the Siwalik fluvial system off of the Plateau during the Quaternary.