Fossil Sirenia of the west Atlantic and Caribbean region. VI. Crenatosiren olseni (Reinhart, 1976)

ABSTRACT

The dugongid sirenian species Halitherium olseni Reinhart, 1976 was based on a skull and skeleton of latest Oligocene age from beds of the Parachucla 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 Dugonginae (which now includes the former subfamily Rytiodontinae), and is the sister group of all other known dugongines, including the Recent Dugong dugon. Because the dugongine clade had both its greatest known diversity 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.