Kishor Kumar

The anatomy of Cambaytherium, a primitive, perissodactyl-like mammal from the lower Eocene Cambay Shale Formation of Gujarat, India, is described in detail on the basis of more than 350 specimens that represent almost the entire dentition and the skeleton. Cambaytherium combines plesiomorphic traits typical of archaic ungulates such as phenacodontids with derived traits characteristic of early perissodactyls. Cambaytherium was a subcursorial animal better adapted for running than phenacodontids but less specialized than early perissodactyls. The cheek teeth are bunodont with large upper molar conules, not lophodont as in early perissodactyls; like perissodactyls, however, the lower molars have twinned metaconids and m3 has an extended hypoconulid lobe. A steep wear gradient with heavy wear in the middle of the tooth row suggests an abrasive herbivorous diet. Three species of Cambaytherium are recognized: C. thewissi (∼23 kg), C. gracilis (∼10 kg), and C. marinus (∼99 kg). Body masses were estimated from tooth size and long bone dimensions. Biostratigraphic and isotopic evidence indicates an age of ca. 54.5 Ma for the Cambay Shale vertebrate fauna, the oldest Cenozoic continental vertebrate assemblage from India, near or prior to the initial collision with Asia. Cambaytheriidae (also including Nakusia and Perissobune) and Anthracobunidae are sister taxa, constituting the clade Anthracobunia, which is sister to Perissodactyla. We unite them in a new higher taxon, Perissodactylamorpha. The antiquity and occurrence of Cambaytherium—the most primitive known perissodactylamorph—in India near or before its collision with Asia suggest that Perissodactyla evolved during the Paleocene on the Indian Plate or in peripheral areas of southern or southwestern Asia.

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.

The lower jaw of a gymnodont fish collected from the lower Eocene Cambay Shale Formation in Gujarat Province, western India, has fused dentaries without a beak and a remarkable series of teeth that are unique among all known fossil and living Tetraodontiformes. The teeth are molariform, with raised spokes radiating inward from the emarginated peripheral edge of the crown. Tooth development is intraosseous, with new teeth developing in spongy bone before they erupt and attach to the dentary by pedicels. Although many of the 110 tooth loci in the fossil have lost their teeth, in life the teeth would have grown to fit tightly together to form a broad and continuous crushing surface. The estimated age of the Cambay Shale vertebrate fauna is ca. 54.5 Ma, making the jaw the second oldest confirmed gymnodont fossil. Preliminary comparisons with extant taxa of gymnodonts with fused dentaries (e.g., Diodon, Chilomycterus, and Mola) show detailed similarities in jaw structure, but further study of the dentition is needed to better understand the evolutionary position of the new fossil. We describe the new gymnodont as †Avitoplectus molaris, gen. et sp. nov., in †Avitoplectidae, fam. nov., and place the family as incertae sedis within Gymnodontes. http://zoobank.org/urn:lsid:zoobank.org:pub:46BF7C65-2241-4B89-B088-6DC6721CD2FD Citation for this article: Bemis, K. E., J. C. Tyler, W. E. Bemis, K. Kumar, R. S. Rana, and T. Smith. 2017. A gymnodont fish jaw with remarkable molariform teeth from the early Eocene of Gujarat, India (Teleostei, Tetraodontiformes). Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2017.1369422.

We describe new skeletal elements of Vastanavis from the early Eocene Cambay Shale Formation of western India, including a small coracoid that represents an unnamed new species, and comment on the relationships between this avian taxon and the recently described Avolatavis from the early Eocene Green River Formation in North America. Like the previously described ones, the new Vastanavis bones resemble those of the late Eocene Quercypsittidae, thus strengthening psittaciform affinities of the Indian taxon. Vastanavis differs from Avolatavis in the presence of a crista medianoplantaris on the tarsometatarsus and in claw morphology, but a fossil from the early Eocene London Clay, which was previously assigned to Vastanavidae, closely resembles Avolatavis in these features and all other osteological aspects. We show that most branches in a recent phylogeny of stem group Psittaciformes collapse after modification of a single erroneous character scoring for Vastanavis. We further describe a morphologically distinctive distal humerus of a small bird resembling the stem group nyctibiid Paraprefica, which was discovered in the most recent excavation in Vastan Lignite Mine.

A new tillodont, Anthraconyx hypsomylus, n. gen. n. sp., is described from the early Eocene Cambay Shale Formation at Vastan Lignite Mine, Gujarat, India. Anthraconyx hypsomylus is the smallest Eocene tillodont and is distinguished by having the most buccally hypsodont cheek teeth of any known esthonychine. The closest dental resemblances are to North American Esthonyx and Azygonyx and European Plesiesthonyx, providing further evidence of affinities between the Vastan local fauna and Euroamerican vertebrate faunas.