Ruminantia

By the Late Eocene (46 million years ago), the three modern suborders had already developed: Suina (the pig group); Tylopoda (the camel group); and Ruminantia (the goat and cattle group).

Differences in stomach construction indicated that rumination evolved independently between tylopods and ruminants ; therefore tylopods were excluded from Ruminantia.

Shared modern nomenclature divides Cetartiodactyla in five subordinate taxa that are also monophyletic: camelids (Tylopoda), pigs and peccaries (Suina), ruminants (Ruminantia), hippos (Ancodonta), and whales (Cetacea).