Many prehistoric hippo fossils are known primarily through fossils of the
lower jaw.
Archaeopotamus, like
Hexaprotodon, has three pairs of
incisors. Unlike other
Hexaprotodon,
Archaeopotamus has a highly elongate
mandibular symphysis. The informal name "narrow muzzled hippos" has been suggested for this genus.
A. lothagamensis A. lothagamensis is a species whose fossils were discovered at
Lothagam, a site southwest of
Lake Turkana in
Kenya and first described in 2000. When first described, the species was classified as
Hexaprotodon lothagamensis, although the significant morphological differences between other
Hexaprotodon species, were noted.
A. lothagamensis was smaller than the modern
hippopotamus and also smaller than
A. harvardi and with a more slender skeleton. It was, however, significantly larger than the modern
pygmy hippopotamus.
A. harvardi A. harvardi is a species of hippo first described in 1977, originally as
Hexaprotodon harvardi. Although the proportions of
A. harvardi and
A. lothagamensis are similar, the former species is significantly smaller. Femurs of
A. harvardi are approximately the same size as those of the modern hippopotamus. Another group of fossils, originally described as
Hexaprotodon sahabiensis or the Abu Dhabi Hippopotamus, are now considered to belong to
A. harvardi or
A. lothagamensis. The fossil record for
A. harvardi is more extensive than for other
Archaeopotamus.
A. harvardi is believed to have had a more
riparian lifestyle than
A. lothagamensis. ==Distribution==