Leptaucheniinae ("Delicate Necks") was a taxon of small, goat-like

oreodont Merycoidodontoidea, previously known as "oreodonts" or " ruminating hogs," are an extinct superfamily of prehistoric cud-chewing artiodactyls with short faces and fang-like canine teeth. As their name implies, some of the better known forms we ...

s with proportionally big heads found throughout

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

during the Late

Oligocene The Oligocene ( ) is a geologic epoch (geology), epoch of the Paleogene Geologic time scale, Period that extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that defin ...

. Because skeletons of ''

Leptauchenia ''Leptauchenia'' is an extinct goat-like genus of terrestrial herbivore belonging to the oreodont family Merycoidodontidae, and the type genus of the tribe Leptaucheniini. The genus was endemic to North America during the Late Oligocene to Ea ...

'' and ''

Sespia ''Sespia'' ("of Sespe Creek") is an extinct genus of oreodont endemic to North America. They lived during the Late Oligocene 26.3—24.8 mya, existing for approximately . ''Sespia'' was cat to goat-sized and desert-dwelling. The genus was clos ...

'' have been found by the literal thousands, they are often quoted as being the most numerous fossil mammals in North America during the Late Oligocene. They had high-crowned, hypsodont teeth which were used to chew gritty vegetation. Because the eyes and nostrils were placed high on the head, it was long assumed that ''Leptauchenia'' and ''Sespia'' were aquatic, or semi-aquatic animals. However, because their fossils have never been found in floodplain deposits or river channels, and their plague-like abundance in fossil sand dunes,

Donald Prothero Donald Ross Prothero (February 21, 1954) is an American geologist, paleontologist, and author who specializes in mammalian paleontology and magnetostratigraphy, a technique to date rock layers of the Cenozoic era and its use to date the climate ...

suggests that they were desert-dwelling animals.Prothero, D. R., and F. Sanchez. 2005. Review of the leptauchenine oreodonts (Mammalia: Artiodacttyla). ''New Mexico Museum of Natural History and Science Bulletin.'' According to Prothero's interpretation, the high-placed eyes and nostrils served to filter out sand while burrowing.

References

Oreodonts Oligocene Artiodactyla Chattian extinctions Chattian first appearances {{paleo-eventoedungulate-stub