Heptodon

Taxonomy

Class: Mammalia

Order: Perissodactyla

Family: Helaletidae

Genus: Heptodon

Species: H. calciculus, H. posticus

When and where Heptodon lived: Heptodon lived in the early Eocene in what is now North America and Asia. Perrisidactyl ungulates were ancestors of the horse, tapir and rhinoceros groups and first appear in North America about more than ten million years after the dinosaur extinction.Heptodon fall into the Ceratomorpha grouping of odd-toed ungulates, consisting of slower, heavier animals like the tapir and rhinoceros. Perrisodactyls, including Heptodon, were the dominant group of large terrestrial browsers throughout the Eocene and into the Oligocene, when the rise of grasses in the Miocene better served the even-toed ungulates (modern examples include deer, cows and sheep) who adapted better to more coarse and less nutritious diet.

General Description

Heptodon resembled a tapir, but probably had an elongated fleshy upper lip instead of a trunk. "Heptodon calciculus was a slender perissodactyl, about forty inches long and eighteen inches high... The feet are extremely interesting because of the elongation of the median digit and the shortening of the lateral digits..." (Osborn and Wortman, 1892).

Heptodon lived at the time of the Paleocene-Eocene Thermal Maximal, so its habitat was probably exceptionally rich in green vegetation. (Secord, Wing and Chew, 2008.) Animals like Malfelis and Oxyaena were likely predators of Heptodon.

Dentition: Heptodon had tall crown teeth for the Eocene. The teeth had strong cross lophs (ridges), which allow shredding of plants.

Bibliography: Osborn, Henry Fairfield and Wortman, J. L., Fossil Mammals of the Wahsatch and Wind River Beds. Colection of 1891. Bulletin of the American Museum of Natural History, Volume IV, 1892. New York: Published by Order of the Trustees. 1892.

Secord, Ross; Wing, Scott L. and Chew, Amy, Stable isotopes in early Eocene mammals as indicators of forest canopy structure and resource partioning. Paleobiology, Volume 34, Issue 2 (March 2008)

Colbert, E. H. and Morales, M., Evolution of the Vertebrates, 4th Ed., John Wiley and Sons, New York, 1991

UniSci, Daily University Science News for Global Warming Episode Between Paleocene and Eocene, by Tim Stephens, featuring the views of Paul Koch and Gabrel Bowen. http://www.unisci.com/stories/20021/0315022.htm

NationMaster - Encyclopedia. http://www.nationmaster.com/encylopedia/Heptodon

NationMaster - Encyclopedia. http://www.nationmaster.com/Perrissodactyla

Text by: Dennis Corcoran

Search the Paleozoo: