Jean-Yves Crochet

New tropical carcharhinids (chondrichthyes, Carcharhiniformes) from the late Eocene-early Oligocene of Balochistan, Pakistan: Paleoenvironmental and paleogeographic implications

New selachians (sharks and rays) have been collected from several late Eocene and early Oligocene marine localities in the Bugti Hills (Balochistan, Pakistan). Two new species of Requiem sharks (close to the Recent ?Bull shark?) are described : Carcharhinus balochensis and Carcharhinus perseus. The rest of the fauna is notable for the strong representation of Carcharhiniformes. These selachian faunas represent a unique tropical association for the Oligocene period and one of the first modern tropical selachian faunas, with modern taxa such as the two new species of ?Bull sharks?, Negaprion sp. and one of the first occurrences of Sphyrna sp. Moreover, these faunas permit paleoenvironmental interpretation of adjacent land masses. The relatively modern aspect of these faunas, compared with other contemporaneous and younger selachian associations from Atlantic and Mediterranean seas, suggests biogeographic isolation of selachian communities living in eastern and western parts of the Tethys before its final closure during the early-middle Miocene.

The Eocene Mammalian Fauna of Chambi (Tunisia) in Its Geological Context

In the Kasserine area of Tunisia there is a Cenozoic basin containing Paleogene continental deposits. Palustrine limestones located at the base of the Paleogene series have yielded the Chambi mammalian fauna. Representatives of the following mammalian orders and families have been found: Marsupialia, Peradectidae; Placentalia, Protheutheria indet.; ?Lipotyphla, ?Erinaceomorpha; Chiroptera, Rhinolophoidea, Nycterididae and Vespertilionoidea, Philisidae; Primates, Adapidae; Rodentia, Zegdoumyidae; Macroscelidea, Herodotinae; Hyracoidea, Pliohyracidae. The analysis of this local fauna provides insights into its position with regards to other North African mammalian faunas and its possible relationships with Eocene Eurasian faunas.

Nouveaux sites d'âges variés dans les remplissages karstiques du Miocène inférieur de Bouzigues (Hérault, Sud de la France): Partie II: faunes 2 (rongeurs),biochronologie et corrélations

The fossil mammal-bearing site of Bouzigues includes three localities of different ages (Bouzigues 1, 1A and 2) within a radius of 10 m. The rodent faunas are analysed and one of the two new species of Bouzigues 2 is described (Myoglis houlezi nov. sp.). On the basis of the degree of evolution of some mammals and the difference in the faunal composition, an age between that of Bouzigues 1 and that of Serre de Verges is proposed for the two new localities. Therefore, they could be more or less contemporaneous with the Estrepouy level. The heterochrony of the Bouzigues fissure fillings bears evidence of several episodes of emptying and infilling of this paleokarst. The faunas analyse shows, for the considered period, a progressive increase of the forest in a warm climate.

New remains of the enigmatic cetartiodactyl Bugtitherium grandincisivum Pilgrim, 1908, from the upper Oligocene of the Bugti Hills (Balochistan, Pakistan)

Newly discovered fossil material of the enigmatic cetartiodactyl Bugtitherium grandincisivum from the upper Oligocene of the Bugti Member of the Chitarwata Formation in the Bugti Hills (Balochistan, Pakistan) is reported. These new specimens consist of two fragmentary muzzles (one preserving the first incisors and belonging to a juvenile) and a fragmentary right mandible with m3. The morphologies of the anterior dentition and m3 provided by these new specimens confirm the validity of the genus Bugtitherium and advocate probable anthracotheriid affinity for the genus rather than entelodontid or suoid affinities, but do not definitively close the debate about Bugtitherium’s familial affinities within Cetartiodactyla. Although still poorly documented, this large-sized anthracotheriid-like cetartiodactyl is a possible key form for understanding the early evolution of hippos, and, in turn, the ancestry of whales, because of both its morphological similarities with hippos and primitive Paleogene whales and its Tethysian distribution.

New material of Seggeurius amourensis (Paenungulata, Hyracoidea), including a partial skull with intact basicranium

ABSTRACT Seggeurius is the basal-most hyracoid known to date, and one of the earliest known fossil afrotherians. This taxon has a dramatic importance in mammalian phylogeny, but until now it was known from dental remains only. Here we describe previously unpublished material of Seggeurius, including some mandibular and maxillary fragments, and a braincase. This study is the first to thoroughly describe and discuss the morphology of the ear region and osseous inner ear of a Paleogene hyracoid. It allows a reappraisal of some important characters that are often used in cladistic analyses of Paenungulata. In particular, it seems that in stem hyracoids the orbit is located caudally, the eustachian sac is absent or reduced, the course of the internal carotid artery is intrabullar and medial, and a deep epitympanic sinus, a basisphenoid contribution to the bulla, and the stapedial artery are present. The cochlear canal is rather flattened, and the secondary common crus was rapidly lost. A cladistic analysis of stem placental mammals highlights three derived traits shared by Seggeurius and stem sirenians (the tuber-shaped postglenoid process, the squared and massive mastoid apophysis of the petrosal, and the presence of a swelling on the septum metacochleare) and supports molecular analysis that hypothesizes a Hyracoidea-Sirenia sister-group relationship. This study demonstrates how useful the petrosal and labyrinthine characters of fossils can be for mammalian phylogenetic inference.