ABSTRACT
The lower and middle Siwalik Group of the Potwar Plateau, Pakistan (Miocene, approximately 18 to 3.5 Ma) is a continuous fluvial sequence that preserves a dense fossil record of snakes. The record consists of approximately 1,500 vertebrae derived from surface-collection and screen-washing of bulk matrix. This record represents 12 identifiable taxa and morphotypes, including Python sp., Acrochordus dehmi, Gansophis potwarensis gen. et sp. nov., Bungarus sp., Chotaophis padhriensis, gen. et sp. nov., and Sivaophis downsi gen. et sp. nov. The record is dominated by Acrochordus dehmi, a fully-aquatic taxon, but diversity increases among terrestrial and semi-aquatic taxa beginning at approximately 10 Ma, roughly coeval with proxy data indicating the inception of the Asian monsoons and increasing seasonality on the Potwar Plateau. Taxonomic differences between the Siwalik Group and coeval European faunas indicate that South Asia was a distinct biogeographic theater from Europe by the middle Miocene. Differences between the Siwalik Group and extant snake faunas indicate significant environmental changes on the Plateau after the last fossil snake occurrences in the Siwalik section.
Jason J. Head. Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, P.O. Box 37012, Washington, DC 20013-7012, USA.
School of Biological Sciences, Queen Mary, University of London, London, E1 4NS, United Kingdom.
KEY WORDS: snakes, faunal change, Siwalik Group, Miocene, Acrochordus.
PE Article Number: 8.1.8A
Copyright: Society of Vertebrate Paleontology May 2005
Submission: 3 August 2004. Acceptance: 13 April 2005.
