A new mammal−bearing locality from the Intertrappean beds (Maastricthian) of Rangapur, Andhra Pradesh, India provides isolated teeth referable to Deccanolestes and a new eutherian, Sahnitherium rangapurensis. Dental comparisons with Cimolestes, Procerberus, and Aboletylestes do not support proposed “palaeoryctoid” affinities for Deccanolestes. Although similarities exist with Otlestes and Batodon, Deccanolestes is currently considered to be of uncertain familial affinities. Sahnitherium rangapurensis exhibits similarities to Procerberus, Paranyctoides, Alostera, Aboletylestes, and Avitotherium, but it is here placed within Eutheria incertae sedis. Despite family level taxonomic uncertainties, the new material confirms the presence of eutherians on the Indian subcontinent during the Late Cretaceous. A Eurasian connection via an early collision or some other dispersal route may explain these paleobiogeographic data, but other hypotheses are considered. In particular, paleogeographic, paleontological, and molecular systematic data hint that boreosphenidan mammals may have had wider distribution on Gondwana during the Cretaceous than previously supported.
The Ypresian Cambay Shale Formation of Vastan Lignite Mine in Gujarat, western India, has yielded a rich vertebrate fauna, including the earliest modern mammals of the Indian subcontinent. Here we describe its assemblage of four frogs, including two new genera and species, based on numerous, diverse and well−preserved ilia and vertebrae. An abundant frog, Eobarbourula delfinoi gen. and sp. nov., with a particular vertebral articulation similar to a zygosphene−zygantrum complex, represents the oldest record of the Bombinatoridae and might have been capable of displaying the Unken reflex. The large non−fossorial pelobatid Eopelobates, known from complete skeletons from the Eocene and Oligocene of Europe, is also identified at Vastan based on a single nearly complete ilium. An abundant “ranid” and a possible rhacophorid Indorana prasadi gen. and sp. nov. represent the earliest records of both families. The Vastan pelobatids and ranids confirm an early worldwide distribution of these families, and the bombinatorids and rhacophorids show possible origins of those clades on the Indian subcontinent.
Vastan Lignite Mine in southeastern Gujarat, India, produces the oldest known Cenozoic land−mammals and the only early Eocene continental vertebrate fauna known from India (e.g., Bajpai et al. 2005; Rana et al. 2005, 2008; Rose et al. 2006, 2008, 2009; Smith et al. 2007; Rage et al. 2008). The fauna comes from the Cambay Shale Formation and has been dated as middle Ypresian (~52 Ma, early Cuisian) based on a common nummulitid foraminiferan from about 15 m above the vertebrate−producing layer (Sahni et al. 2006; Rana et al. 2008). However, a recent study of dinoflagellate cysts from the section suggests that the deposits may be as old as 54–55 Ma (Garg et al. 2008). Although some elements of the fauna, such as anthracobunids and lagomorphs, have Asian affinities, a surprising number of taxa among the snakes, bats, insectivores, primates, rodents, and artiodactyls appear to be most closely related to early Eocene European or North American taxa. This may simply reflect the poor state of knowledge of contemporary south Asian vertebrate faunas; alternatively, it might be evidence of previously unsuspected early Eocene faunal exchange between Europe and southwest Asia. We report here two teeth of a tillodont from Vastan Mine, which constitute the first record of the mammalian order Tillodontia known from India. Despite the much greater generic diversity of tillodonts in Asia than elsewhere, the Vastan tillodont shows clear affinities with Euramerican esthonychines.
The early Eocene (Ypresian) Cambay Formation of Vastan Lignite Mine in Gujarat, western India, has produced a diverse assemblage of snakes including at least ten species that belong to the Madtsoiidae, Palaeophiidae (Palaeophis and Pterosphenus), Boidae, and several Caenophidia. Within the latter taxon, the Colubroidea are represented by Russellophis crassus sp. nov. (Russellophiidae) and by Procerophis sahnii gen. et sp. nov. Thaumastophis missiaeni gen. et sp. nov. is a caenophidian of uncertain family assignment. At least two other forms probably represent new genera and species, but they are not named; both appear to be related to the Caenophidia. The number of taxa that represent the Colubroidea or at least the Caenophidia, i.e., advanced snakes, is astonishing for the Eocene. This is consistent with the view that Asia played an important part in the early history of these taxa. The fossils come from marine and continental levels; however, no significant difference is evident between faunas from these levels. The fauna from Vastan Mine includes highly aquatic, amphibious, and terrestrial snakes. All are found in the continental levels, including the aquatic palaeophiids, whereas the marine beds yielded only two taxa. Vastan Mine is only the second locality in which the palaeophiids Palaeophis and Pterosphenus co−occur. The composition of the fauna from Vastan is on the whole similar to that of the early Eocene of Europe; however, comparisons with early Eocene faunas of other continents are not possible because they are poorly known or unknown.
A new ailuravine rodent, Meldimys musak sp. nov. (Mammalia: Rodentia, Ischyromyidae), is recorded from the lower Eocene lignites of western India. It is the oldest record of Rodentia from India. M. musak is more derived than the earliest Eocene ailuravine Euromys cardosoi from Portugal and more generalized than late early Eocene E. inexpectatus and Ailuravus michauxi from France. Its dental morphology closely corresponds to the middle early Eocene species M. louisi, which lived about 52 Ma in Western Europe. Meldimys was previously known only from Europe, and ailuravines were previously reported only from Europe and North America. Its occurrence in India allows the first direct correlation between the early Eocene land mammal horizons of Europe and India, and raises the possibility of a terrestrial faunal exchange between India and Eurasia close to the Palaeocene–Eocene transition.
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.