North Dakota Stratigraphy Merycoidodon ROCK ROCK UNIT COLUMN PERIOD EPOCH AGES MILLIONS OF YEARS AGO Common Name: Holocene Oahe .01 Sheep-like mammal Coleharbor Pleistocene QUATERNARY Classification: 1.8 Pliocene Unnamed 5 Miocene Class: Mammalia 25 Arikaree Order: Artiodactyla Family: Merycoidodontida Brule Oligocene 38 Skull and lower jaws of the sheep-like mammal, Merycoidodon South Heart Chadron Chalky Buttes culbertsoni. Brule Formation. Stark County. Specimen on exhibit Camels Butte Eocene Golden at the North Dakota Heritage Center in Bismarck. Width 198 Valley 55 Bear Den mm. North Dakota State Fossil Collection ND303.1. Sentinel Butte Description: TERTIARY Merycoidodon was a member of the now extinct family, Merycoidodontidae, which are also sometimes called oreodonts. Bullion These animals had some features that are typical of pigs and some Paleocene Creek features that are typical of camels. They possessed advanced teeth with long-lasting grinding surfaces adapted for effective side Slope to side chewing of vegetation. Merycoidodon was sheep size, Cannonball about 4 feet in length, but probably appeared more pig or peccary Ludlow 65 like. They were heavily built with short fore-toed legs and were not Hell Creek efficient runners. Fossils of Merycoidodon are common indicating that these browsing animals lived in large herds on the North Fox Hills Dakota savanna about 30 million years ago. ACEOUS Pierre CRET 84 Niobrara Carlile Carbonate Calcareous Shale Claystone/Shale Siltstone Sandstone Sand & Gravel Mudstone Lignite Glacial Drift Merycoidodon. Painting courtesy of Simon and Schuster Publishing Company. Locations where fossils have been found ND State Fossil Collection Prehistoric Life of ND Map North Dakota Geological Survey Home Page.