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. The only exception to this rule are cetaceans and maybe some other extinct artiodactyls.
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 modern species like camels, laminins (llamas, alpacas), hogs, peccaries, hippos, rorquals, right whales, pygmy right whales, gray whales, oceanic dolphins, monodontids (belugas, narwhals), porpoises, river dolphins, baijis, sperm whales, beaked whales, chevrotains, giraffoids (giraffes, pronghorn), New World deer, Old World deer, water deer, musk deer and bovids. Sometimes it is defined that the group excludes whales, dolphins and porpoises (Cetacea) even though DNA sequence data indicate that they share a common ancestor, making the group paraphyletic. DNA evidence, suggests that hippos are more closely related to whales than to camelids, suines and even ruminants, indicating that, through definition, cetaceans should be considered artiodactyls. One 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 of terrestrial artiodactyls greater flexibility.
In Walking with... SeriesEdit
The episode features Ambulocetus, a carnivorous cetacean, that still has legs that allow the animal to walk on land. Artiodactyls have recently evolved by that time, and soon already evolved to various, mostly omnivorous creatures. Cetaceans were the ones who were more highlighted, given their unprecedented adaptation to the watery environment.
In the episode, several other artiodactyls are shown. Cetaceans are the most featured creatures, focusing in the large totally aquatic and marine Basilosaurus. Without any competion from other marine animals (as most giant sea reptiles were extinct), cetaceans ruled the oceans, and diversified from agile and graceful Dorudon to the apex predator of the oceans, the Basilosaurus. On land, artiodactyls were evolving and diversifying fast as well, as it can be seen with Andrewsarchus, one of the largest land carnivorous mammals in history. Although, these land predators will enter in decline, leaving mostly omnivorous and herbivorous species.
This episode features entelodonts, distant cousin to the modern hippos and cetaceans, and even more distant to the modern swine. Some were as big as modern rhinos, and these animals had brains no bigger than an orange, and unusually for ungulates, they were strongly omnivorous, or even carnivorous. Still, they could fall as prey for other animals, such as Hyaenodon, and they had to avoid herbivorous Indricotheres as well.
Few artiodactyls are seen in the episode, with only one brief cameo of a warthog (possibly Metridiochoerus). However, they were surely very abundant at that time.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. Other artiodactyls, like the saiga antelopes and bisons are also found abundantly in the same region.
Antilopes are often seen in the show.Homo erectus stalking a wildebeest. Though the antelope was able to outrun the ancient humans at first, eventually H. erectus were able to exhaust and killed it. A giraffe is also briefly seen in the episode.
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.
The episode features Basilosaurus and Dorudon in the Eocene, where cetaceans started to pop up for the first time in the oceans. Next, in the Pliocene, an Odobenocetops can be seen being chased by a Megalodon. Here, cetaceans have notoriously diversified.
The episode features another artiodactyl: the Cetotherium. This whale is briefly seen as a prey for Megalodon. This species is a filter feeder, feeding on small invertebrates and fish that live in the water. This shows how much cetaceans have diversified since the Eocene.