FOSSIL SIRENIA OF THE WEST ATLANTIC AND CARIBBEAN REGION - VI - CRENATOSIREN OLSENI (REINHART, 1976)

The dugongid sirenian species Halitherium olseni Reinhart, 1976 was ba sed on a skull and skeleton of latest Oligocene age from beds of the P arachucla Formation, exposed on the Suwannee River in northern Florida . The new genus Crenatosiren was established for it by Domning in 1991 . New specimens of this species, mostly from the late Oligocene Ashley and Chandler Bridge formations in South Carolina, are described here. C. olseni is a small dugongid characterized by tusks of moderate size and a very deep nasal incisure. It is a member of the subfamily Dugon ginae (which now includes the former subfamily Rytiodontinae), and is the sister group of all other known dugongines, including the Recent D ugong dugon. Because the dugongine clade had both its greatest known d iversity as well as its most primitive known member (Crenatosiren) in the West Atlantic-Caribbean region, it seems likely to have arisen in the New World, apparently during the Oligocene.