Les bovidae (Artiodactyla: Mammalia) du miocene du sous-continent indien, de la peninsule arabique et de l'afrique: Biostratigraphie, biogeographie et ecologie
Abstract Supported by the study of Miocene bovids, mainly from the Indian Subcontinent, the Arabian Peninsula and Africa, a provisional synthesis of the bovid biogeographical history is provided. Different aspects are examined successively: the initial bovid radiation, the evolution and biogeography of the Boselaphini, the intercontinental faunal exchanges, the biostratigraphic correlations, the emergence of the Ethiopian fauna and some of the major characteristics of the evolution of the palaeoenvironments. Two successive bovid phases characterizing their early history are accepted. The first one took place during the “mammal units” NM 4 to 6 and concerns mainly the Caprinae and the Antilopini. The Boselaphini seem to have appeared later and, during the second phase, their initial radiation took place, apparently, in the Indian Subcontinent. There, the success of the Boselaphini is linked both to geographical isolation and to the persistence of more or less closed environments south of the Himalayas. During this second phase (NM 7–8), the specific diversity of the bovids is increasing especially in Asia and Africa. Secondly, the problems concerning the Early Miocene terrestrial faunal exchanges after the establishment of the land connection between the Afro-Arabian plate and Asia sensu stricto are discussed. New discoveries in Saudi Arabia provide evidence of the occurrence of two successive faunal exchange phases, the earlier preceding the time of the Dam deposits in eastern Saudi Arabia (NM 5), the second one being probably posterior to the Langhian transgression (NM 6). Afterwards, during the Middle and Late Miocene, nine bovid taxa are involved in the migration between Asia and Africa. While the immigration into Eurasia seems to have been restricted, the immigration into Africa was more extensive and therefore affected the bovid fauna more profoundly. The emergence of the true Ethiopian fauna took place between 11-10 m.y. and 7 m.y. The bovids from the Grosseto lignites in Tuscany are here considered as being of African origin. Lastly, from an ecological point of view, the concordance of the climatic deterioration with the appearance of mosaic-savanna biotopes at the beginning of the Middle Miocene, between the Arabian Peninsula and the lower latitudes near the present-day equator, must be noticed. Towards the end of the Miocene, the Saharo-Arabian belt no longer constituted an obstacle to latitudinal dispersal for larger mammals. North Africa may at that time have been a refuge for late-surviving Eurasian forms.