The osteology and paleoecology of the giant otter Enhydritherium terraenovae

Abstract

ABSTRACT The giant otter Enhydritherium terraenovae, a New World taxon thought to be related to both the Old World otter Enhydriodon and the extant sea otter Enhydra, was originally described on the basis of relatively limited material, mostly dental. However, an incomplete skeleton of E. terraenovae recovered from the early Hemphillian Moss Acres Racetrack site in northern Florida includes a skull, mandible, part of the axial skeleton, and most of both the fore- and hindlimbs, adding greatly to knowledge of this animal. On the basis of this new material, the osteology of this species is described in detail for the first time, with its diagnosis revised accordingly. This new osteological information, along with information about the nature of the Moss Acres Racetrack site, allows such paleoecological and functional aspects of E. terraenovae as habitat preference, mode of swimming, and diet to be inferred or interpreted in a detail previously impossible. E. terraenovae: 1) was a habitat generalist rather than a marine specialist, as previously thought; 2) was reasonably competent for terrestrial locomotion; 3) extensively used its forelimbs during swimming like living otariid seals, in contrast to the hindlimb-specialized Enhydra; and 4) had a generalized diet, potentially including soft items such as fish, as well as hard items, such as thick-shelled molluscs.