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Diversity of the adapisoriculid mammals from the early Palaeocene of Hainin, Belgium

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De Bast E. , Sige B. , Smith T.

Acta Palaeontologica Polonica

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2012

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tom 57

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nr 1

EN

Adapisoriculidae are an enigmatic group of small mammals known from the late Cretaceous of India, and from the early Palaeocene to early Eocene of Europe and Africa. Based on their primitive dental morphology, they have been classified as didelphids, nyctitheriids, leptictids, mixodectids, tupaiids, and palaeoryctids. While the latest hypothesis based on dental morphology suggests an affinity with Lipotyphla, postcranial remains indicate a close relationship with Euarchonta. Here, we present new adapisoriculid dental remains from the early Palaeocene locality of Hainin (Belgium). Adapisoriculidae are particularly abundant in Hainin, where they represent about one third of the mammalian fauna, offering new insights into both their specific and generic phylogenetic interrelationships. We describe three new species (Afrodon gheerbranti sp. nov., Bustylus folieae sp. nov. and Proremiculus lagnauxi gen. et sp. nov.) and document the previously unknown lower dentition of Bustylus marandati. The diversity of dental morphologies observed in the Hainin fauna suggests different interrelationships than previously suggested. In particular, the genus Proremiculus is considered morphologically intermediate between Afrodon and Remiculus, and the latter is no longer recognised as the sister group of Adapisoriculus. Although the highest diversity of adapisoriculids occurs in Europe, the oldest and most primitive members of the family were found in India and Africa, respectively. The geographic origin of the family could thus be located in any of these three continents, depending on the importance attributed to each of these factors. The coexistence of primitive and derived adapisoriculids at Hainin might indicate a very quick diversification in Europe, probably starting around the K−T boundary.

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Dental and tarsal morphology of the European Paleocene-Eocene 'condylarth' mammal Microhyus

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Tabuce R. , Antunes M. T. , Smith R. , Smith T.

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tom 51

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nr 1

EN

New dental and postcranial remains of the alleged louisinine hyopsodontid “condylarth” Microhyus from the European Paleocene/Eocene transition are described, and prompt a reevaluation of the genus. New specimens belonging to Microhyus musculus from Dormaal (MP7, Belgium) provide the first evidence of the lower dentition of the type species. We describe M. musculus? from Pourcy (MP7, France) and cf. Microhyussp. from Berru (MP6a, France). A rich original assemblage of M. reisi from Silveirinha (MP7, Portugal) allows a detailed description of the morphological dental variation within that species. Well−preserved astragali and calcanei from Silveirinha can be confidently attributed to Microhyus reisi. Functional analysis of these elements suggests that Microhyus was a terrestrial mammal capable of rapid running or jumping. The pedal morphology of Microhyus is very similar to that of Paschatherium. These louisinines share some derived characters with the hyopsodontids Apheliscus and Haplomylus (e.g., the occurrence of a cotylar fossa on the astragalus) but they differ from Hyopsodus. Therefore, in view of the pedal morphology alone, the hyopsodontids may be polyphyletic. Given the dental similarities between Microhyus and the early representatives of the order Macroscelidea, we compared the tarsal morphology of louisinines with that of modern macroscelidids (Paleogene tarsal remains are currently unknown for this group). Macroscelidids and louisinines present some similarities in their astragalar morphology; however, the macroscelidid astragalus appears to be too specialized to be compared with that of Microhyus and Paschatherium.

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First tillodont from India: Additional evidence for an early Eocene faunal connection between Europe and India?

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Rose K. D. , Rana R. S. , Sahni A. , Kumar K. , Singh L. , Smith T.

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nr 2

351-355

EN

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.

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Early Eocene frogs from Vastan Lignite Mine, Gujarat, India

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Folie A. , Rana R. S. , Rose K. D. , Sahni A. , Kumar K. , Singh L. , Smith T.

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nr 3

EN

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.

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A diverse snake fauna from the early Eocene of Vastan Lignite Mine, Gujarat, India

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Rage J. C. , Folie A. , Rana R. S. , Singh H. , Rose K. D. , Smith T.

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2008

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tom 53

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nr 3

EN

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.