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Fossil Sirenia of the West Atlantic and Caribbean Region. II. Dioplotherium manigaulti Cope, 1883

1989; Taylor & Francis; Volume: 9; Issue: 4 Linguagem: Inglês

10.1080/02724634.1989.10011774

1937-2809

Daryl P. Domning,

Evolution and Paleontology Studies

ABSTRACT The holotype of Dioplotherium manigaulti Cope, 1883 was originally discovered in the phosphate beds that were formerly mined near Charleston, South Carolina. These deposits range from Eocene or Oligocene to Pliocene in age. D. manigaulti is now known by a skull (described here) from the early Miocene Hawthorne Group of northern Florida, which suggests that the holotype and other fragmentary remains from South Carolina and Florida are also probably early Miocene in age. The Old World early Miocene genus Rytiodus, “Halitherium” olseni from the early Miocene of Florida, and Dioplotherium all belong in the dugongid subfamily Rytiodontinae. This reveals for the first time that rytiodontines probably had their origin and greatest diversity in the New World. The more derived rytiodontines have enlarged, bladelike, self-sharpening tusks that may have been used to dig up seagrass rhizomes. The living Dugong may have evolved its large tusks for a similar reason, but now appears to use them chiefly in social interactions.