However this was later shown to be incorrect, with more complete sequences finding Hippidion as an outgroup to all living equines and less closely related to living equines than the "New World stilt legged horse", Haringtonhippus francisci.
Earlier research suggested that Hippidion was part of the equine family tree, but later genetic analyses showed that it was actually outside this group; instead, it was more closely related to the "New World stilt-legged horse," Haringtonhippus francisci.