Early Eocene artiodactyls (Mammalia) from Western India

Abstract

The Cambay Formation at Vastan Mine in Gujarat, western India, has yielded the oldest artiodactyls and other land mammals from India, which are dated as middle Ypresian (~53 Ma) based on foraminiferids. Here we describe new dentitions, including dentaries and upper teeth of Diacodexis indicus (= Gujaratia indica) from Vastan. These provide better characterization of this Asian diacodexeid (Artiodactyla: Mammalia) than was available earlier. A new combination, Diacodexis indicus, is proposed in place of Gujaratia indica, and G. pakistanensis is referred back to Diacodexis. A new, very small species of Diacodexis, D. parvus, is reported based on isolated teeth. Whereas D. indicus is approximately the size of the largest known species of Diacodexis, D. parvus represents the smallest recorded species of the genus and is one of the smallest known artiodactyls. Diacodexeidae indet. from Vastan is exemplified by a fragment of a dentary and an upper molar, which are of intermediate size. Several isolated teeth represent a new genus and species, unrelated to Diacodexeidae, and are assigned to Artiodactyla indet. pending discovery of more adequate specimens. Early Eocene diacodexeid postcrania are described for the first time from India. Early Eocene artiodactyls from India are phenetically close to Euroamerican species of Diacodexis, providing further evidence of phylogenetic connections particularly with European faunas. A few postcranial features of the Vastan artiodactyls are also seen in primitive archaeocetes (Cetacea) indicating a possible relationship between Vastan artiodactyls and basal Cetacea.