This Order Artiodactyla is the most successful order
of terrestrial ungulates today. There are 3 suborders:
: pigs, peccaries & hippopotami: primitive artiodactyls.
: camels & llamas: intermediate artiodactyls.
: cattle, antelopes, deer and giraffes: advanced artiodactyls.
Artiodactyls are united by several features:
- the feet are either 2 or 4-toed.
- their feet are paraxonic: the line of symmetry
passes between digits 3 and 4.
- the astralagus has a so-called 'double pulley'
whereby both the connecting surfaces allow a rolling action giving
greater freedom of movement in the ankle. Other ungulates lack
- the pre-molars are less like the molars than in most
The Artiodactyla did not undergo a major adaptive
radiation until the end of the Eocene epoch, some 35 million years
ago, even though the first artiodactyls appeared some 20 million
years earlier. The three suborders had all separated by the early Oligocene.
The Phylogeny of the Artiodactyla
The three suborders are related as shown below. The
suborders Tylopoda and Ruminantia are more closely related to each
other than to the Suina, and this is reflected in their
being grouped together under the name 'Neoselenodontia'.
The tylopods were formerly included in the Ruminantia.