Elomeryx is an anthracothere. Anthracotheres are a group of large, relatively primitive artiodactyls that ranged across much of Eurasia and Africa in the Tertiary and Pleistocene. In North America, the group is much more limited in distribution; fossils range in age from the Eocene through to the mid Miocene (17.5 million years ago) and are found mostly in South Dakota and the adjacent states. Anthracothere fossils are often found concentrated in the remains of ancient waterways, suggesting that they may have had a semi-aquatic lifestyle similar to modern hippos, although they lack the anatomical specializations that characterize hippos as aquatic animals.

Elomeryx lived in the early Oligocene, around 30 million years ago. Evidence from fossil soils and associated plant and animals suggests that this was a period of gradually increasing aridity, with the environment shifting from closed canopy woodlands to more open, savanna-like shrublands with forests concentrated along the edges of rivers and streams. In the end, it may have been this on-going climate change, combined with relative rarity and lack of species diversity, which was responsible for the extinction of the group in North America.