An Introduction to Desmostylians
The Desmostylia are an extinct group of marine mammals. They are both strange and enigmatic creatures known only from deposits of the Late Oligocene and the Miocene. Fossils assigned to four genera have been found in Japan and along the west coast of Mexico and the United States, to as far north as Washington.
Fossils of Desmostylus were first described in 1888 by Othniel Marsh, from marine deposits collected in Alameda County, California. The fossils were considered to represent Sirenians, and subsequent fossils found in Japan were interpreted as possibly being primitive Proboscideans (elephants) or Sirenians (sea-cows), though not without significant differences from either group.
Desmostylians are noted for having a number of bizarre and unique physical features, such as the tooth shown at right. The teeth and the pattern of wear in their enamel are unlike that observed in any modern mammal, and so no one is yet certain just what these short-tusked, shovel-jawed animals ate. This problem is compounded by the changes in coastal marine floras of the Miocene as kelp forests developed. The best evidence suggests they were herbivores, but anything beyond that is a guess…
(read more: UCMP - Berkeley)
(images: T - Nobu Tamura; BL - Darwin’s Bulldog, BM - Sarah Rieboldt, © Univ. of Cali. Mus. of Paleontology; BR - uncredited)
