What is "archaeopotamus"

Archaeopotamus is an extinct genus of Hippopotamidae that lived between 7.5 and 1.8 million years ago in Africa and the Middle East. The genus was described in 2005 to encompass species of hippos that were previously grouped in Hexaprotodon.

Archaeopotamus means "the ancient of the river". Of all identified hippos, only Kenyapotamus is older. Kenyapotamus, however, is only known from partial fossils; Archaeopotamus is the oldest well-identified hippo.