A new species of the snake Madtsoia from the Upper Cretaceous of India and its paleobiogeographic implications

ABSTRACT

We report the discovery of a new species of the snake Madtsoia from infratrappean horizons of Late Cretaceous age in Pisdura, central India. Recovered vertebrae are large (1.83 cm long; 4.35 cm tall) and pertain to a snake that was ca. 5 m long. Discovery of Madtsoia in India extends the geographic distribution of the genus and represents only the second species known from the Cretaceous. Vertebrae of Madtsoia pisdurensis sp. nov. are strikingly similar to those of M. bai and M. camposi (South America) and M. madagascariensis (Madagascar), but can be distinguished from them by a unique process on the hemal keel, which is low, flat, and triangular in outline. Whereas the eastern Gondwanan species of Madtsoia (M. madagascariensis, M. pisdurensis) are Late Cretaceous in age, the western Gondwanan species (M. bai, M. camposi) are Paleogene in age. Geophysical evidence suggests that land connections between South America, Madagascar, and Indo-Pakistan were severed by at least 100–90 Ma, which implies that Madtsoia achieved its broad geographic distribution either by (1) origin and dispersion before the end of the Turonian; or (2) the presence of an unrecognized land connection persisting into the latest Cretaceous. Both hypotheses predict that Madtsoia will be discovered in Mesozoic strata of South America, where it survived the Cretaceous-Paleogene mass extinction.

ACKNOWLEDGMENTS

This research was conducted under the auspices of a joint collaboration between the Geological Survey of India, Ministry of Mines, and the University of Michigan. We thank Shri N. K. Dutta, Director General, GSI, Kolkata, and Shri K. K. K. Nair, Deputy Director General, GSI Central Region, Nagpur, for excellent cooperation for carrying out joint study under the collaborative program. We thank Kailash Ghodam, Shanan Peters, and Monica Wilson for field assistance in 2007. We thank C. Mehling and D. Krause for access to collections in their care. Thanks to F. Carlini and D. Croft for assistance with age of the Casamayoran SALMA. B. Miljour prepared the halftone illustrations in Figure 2 and prepared the map and edited the photos in Figure 3. We thank J.-C. Rage and an anonymous reviewer for providing useful comments that improved the final version of the manuscript. J.-C. Rage is also thanked for permission to reproduce the images of M. camposi that appear in Figure 3. Research was funded by the National Geographic Society Committee for Research and Exploration grant 8127-06 (to J.A.W.), the Geological Survey of India (to D.M.M.), and an NSERC Discovery Grant (to J.J.H.).

Handling editor: Sean Modesto.