The group at the present day is divided into Girafjidae (giraffe and okapi), Cervidae (deer), Antilocapridae (prongbuck), and Bovidae (oxen, sheep, goats, antelopes, &c.).
No true antelopes are American, the prongbuck (Antilocapra), which is commonly called "antelope" in the United States, representing a distinct group; while, as already mentioned, the Rocky Mountain or white goat stands on the borderland between antelopes and goats.
When hunting antelope (prongbuck) and deer the coyotes spread out their pack into a wide circle, endeavouring to surround their game and keep it running inside their ring until exhausted.
Female prongbuck may or may not have horns.
From the fact that the bony horn-core of the hollow-horned ruminants first develops as a separate ossification, as do the horns of the giraffe, while the pedicle of the antlers of the deer grow direct from the frontal bone, it has been proposed to place the hollow-horned ruminants (inclusive of the prongbuck) and the giraffes in one group and the deer in another.