In comparison with later known
desmostylians,
Behemotops had more
elephantine tooth and jaw features. It had cusped
molars that more resembled those of
mastodons or other land
ungulates than those of later
Desmostylus, which exhibited odd "bound-pillar" shaped molars which may have evolved in response to the grit from a diet of sea-grass. Discovery of
Behemotops helped place desmostylians as more closely related to
proboscideans than
sirenians, although relationships of this group are still poorly resolved.
B. proteus was larger than
Desmostylus, measuring in length, in height and in body mass.
B. katsuiei had an estimated body length of , making it the smaller of the two species. but was later placed in its own genus,
Seuku, in 2014. The first specimen, USNM 186889, a massive tusk in fragments of a mandible — was found in
Lincoln County, Oregon () in 1969. In 1977, at the same location, fossil collector
Douglas Emlong discovered a poorly preserved half right mandible — USNM 244033 — matching the first specimen. This mandible became the holotype of
Seuku emlongi (then described as
B. emlongi) when described by .
B. emlongi was later eventually made a synonym of
B. proteus in 1994, before being removed from the genus altogether. ==History of discovery==