NEW DIATOMYID AND BALUCHIMYINE RODENTS FROM THE OLIGOCENE OF PAKISTAN (GUGTI HILLS, BALOCHISTAN): SYSTEMATIC AND PALEOBIOGEOGRAPHIC IMPLICATIONS
Laurent Marivaux and Jean-Loup Welcomme, Journal of Vertebrate Paleontology, 2003, 23(2):420–434
The rodents (Baluchimyinae and Fallomus) from the Bugti, Sulaiman, and Ladakh deposits (Indian subcontinent) were originally considered a distinct early Miocene group that arose via local evolution from the Eocene Chapattimyidae in the Indo-Pakistan province. The Bugti Member, the lowermost continental beds of the previously ascribed Miocene Chitarwata Formation, is now considered to be Oligocene. A new continental vertebrate locality from the basal part of the Bugti Member (Paali nala C2) has yielded an important early Oligocene small mammal fauna including a well-diversified rodent assemblage that allows revision of the age attributed to the classic Bugti rodent fauna. Additional specimens (mainly isolated teeth) allow a systematic review of Fallomus (Diatomyidae) and Hodsahibia (&147;Baluchimyinae&148;), and two new species are described for each genus (F. ginsburgi, sp. nov.; F. quraishyi, sp. nov.; H. gracilis, sp. nov.; and H. beamshaiensis, sp. nov.). The presence of several higher rodent taxa at Paali nala C2 suggest that there was not an extended period of mid-Tertiary faunal isolation on the Indian subcontinent, nor an abrupt turnover between Chitarwata and Lower Siwalik rodent faunas. &147;Baluchimyines,&148; here considered Hystricognathi incertae sedis, are part of a diverse assemblage of hystricognathous rodents in South Asia at the end of the Paleogene. A close phylogenetic relationship between &147;baluchimyines&148; and earliest Asian hystricid rodents is plausible.