Entelodonts.
Artiodactyls, or even-toed ungulates, are mammals, whose weight is born on the third and fourth toes of each leg, rather than on a single toe, as in horses.
Facts
Artiodactyla comes from (Greek: ἄρτιος (ártios), "even", and δάκτυλος (dáktylos), "finger/toe"), so the name "even-toed" is a translation of the description.
This group includes pigs, peccaries, hippopotamuses, camels, llamas, chevrotains (mouse deer), deer, giraffes, pronghorn, antelopes, sheep, goats, and cattle. The group excludes whales (Cetacea) even though DNA sequence data indicate that they share a common ancestor, making the group paraphyletic. The phylogenetically accurate group is Cetartiodactyla (from Cetacea + Artiodactyla).
There are about 220 artiodactyl species, including many that are of great dietary, economic, and cultural importance to humans.
A further distinguishing feature of the group is the shape of the astragalus (talus), a bone in the ankle joint, which has a double-pulley structure. This gives the foot greater flexibility.
In Walking with... Series
Walking with Beasts
Land of Giants
This episode features entelodonts, distant cousin to the modern swine. As big as modern rhinos, these animals had brains no bigger than an orange, and unusually for ungulates, they were strongly omnivorous, or even carnivorous. Still, they were prey for other animals, such as Hyaenodon, and they had to avoid Indricotheres as well.
Mammoth Journey
This episode featured Megaloceros, also known as the Irish elk.
It was shown rutting and fighting for females in autumn, while the mammoths migrated to the south. This episode also shows a group of Cro-Magnons successfully ambushing and killing one of the stags.
Walking with Cavemen
Savage Family
This episode features a family of Homo erectus stalking a wildebeest.
A blue wildebeest (Wiki image).
Though the antelope was able to outrun the ancient humans at first, eventually H. erectus were able to exhaust and killed it.
'The Survivors
This episode featured a family of Homo heidelbergensis ambushing a Megaloceros. Though the giant deer was able to hurt one of the brothers, the rest of the family killed it.