Publications de nos chercheuses et chercheurs

Between 1999 and 2004, eight isolated molars of a strange mammal were discovered from lower Oligocene deposits of the Bugti Hills, Pakistan (Paali Nala, Dera Bugti locus C2; Bugti Member; lower Chitarwata Formation). Because of their unusual morphology, these molars have long remained enigmatic. Extensive comparisons with fossil eutherian and metatherian mammals and the recent description of new paroxyclaenids (Mammalia, Cimolesta) from the early Eocene (Ypresian) of Europe have highlighted the plausible affinities of these teeth from the Oligocene of Pakistan, and pointed to a referral to Paroxyclaenidae. The dental morphology of this taxon is singular among Paroxyclaenidae, and as such it allows us to propose here a new species and a new genus: Welcommoides gurki. The occurrence of a paroxyclaenid in the Oligocene of Pakistan remains somewhat unexpected inasmuch as these mammals were so far only known in the Eocene of Europe. Welcommoides gurki is the largest paroxyclaenid (ca. 4.2 kg) ever discovered, and is assigned to the subfamily Merialinae, which became extinct in Europe around the Ypresian/Lutetian transition, long before the occurrence of this new taxon from Pakistan. Welcommoides displays a suite of unusual characters compared with merialines, suggesting that this South Asian lineage had diverged for some time from its European Ypresian counterparts. Such a hypothesis is supported by the faunal similarities between European and Indian Subcontinent faunas during the Ypresian. Moreover, our discovery strengthens support for the hypothesis that low latitudes of South Asia were a tropical refugium, at least during the first steps of the global climatic deterioration started at the Eocene/Oligocene transition.