We report a new genus and species of herbivorous mammal, Pahelia mysteriosa, from the early Eocene Cambay Shale Formation, Tadkeshwar Lignite Mine, Gujarat, India. The new taxon, approximately the size of a small phenacodontid (e.g. Ectocion parvus), is represented by three mandibular fragments, the most complete of which documents nearly the entire symphysis and mandibular body plus P3–M3. Pahelia has incipiently selenolophodont molars with strong exodaenodonty, absent paraconids, weak but distinct entolophids, and prominent ectostylids. Molar size increases distally, but M3 does not develop a prominent third lobe. Premolars are simple, with prominent protoconids and short talonids but little development of other trigonid cusps. The mandibular symphysis is strongly fused, and there is an enlarged alveolus for an anterior tooth. The combination of features present in the new taxon does not closely match that of any known mammal, but there are some similarities to a diversity of ungulates from Africa, Asia, Europe and North America. Preserved morphology is insufficient to assess the affinities of the new taxon with confidence, but a link to Quettacyonidae, also endemic to the Indian subcontinent, is morphologically and biogeographically plausible. If this scenario is correct, it suggests that P. mysteriosa could be a part of the endemic mammalian fauna of India prior to its initial faunal contact with Asia.
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The early Eocene Cambay Shale Formation in Gujarat State, India has produced a rich mammalian fauna, including the earliest artiodactyls, perissodactyls, primates, hyaenodonts, rodents, lagomorphs, chiropterans, and tillodonts from the Indian Subcontinent. While some of these groups show endemism at the generic or familial level, all belong to clades that are widely distributed across Laurasian continents, and some show particularly close similarities to contemporary taxa from other continents, particularly Europe. We report here a distinctive new taxon, represented by a mandible with p3-m3 and a second mandibular fragment with m3. The morphology of the new taxon is broadly comparable to diverse early ungulates from around the world but shows a unique suite of features including a strongly fused mandibular symphysis, enlarged anterior tooth alveolus, simple premolars lacking paraconids and with only a rudimentary metaconid on p4, progressive size increase of the molars distally, molar exodaenodonty/unilateral hypsodonty, molar paraconids absent, hypoconulids absent on m1-2, incipient development of selenodont buccal cusps and an incipient entolophid formed by a transverse entoconid, well-developed, and prominent m3 hypoconulid. One particularly distinctive feature is the presence of large, cuspate ectostylids on molar hypoflexids. While there are similarities to a variety of taxa, most notably periptychids, louisinids, early African “ungulates” (Abdounodus, Ocepeia), and even early anthracotheres, none of these is detailed enough to indicate a close relationship, and all appear to be better interpreted as convergence. Our present understanding suggests that these fossils represent a new family of “condylarth”-grade ungulates perhaps endemic to India. Although their overall adaptations are very different, there are some intriguing similarities to another group of enigmatic Eocene mammals from the Indian Subcontinent, Quettacyonidae. While more material is needed to test this possible relationship, quettacyonids and the new taxon may represent remnants of the eutherian fauna present in India prior to its first faunal exchange with the northern continents, and the new taxon likely has a lengthy, undocumented history in the Indian Paleocene. Grant Information: Fieldwork and research supported by Leakey Foundation, National Geographic Society, Wadia Institute of Himalayan Geology, and Belgian Science Policy Office.
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