What order of mammals includes deer, cattle, pigs, and camels?

The order of mammals that includes deer, cattle, pigs, and camels is Artiodactyla.

Artiodactyla are commonly called even-toed ungulates because their weight is typically borne through the third and fourth toes. Deer and cattle belong to the ruminant branch, pigs belong to Suina, and camels belong to Tylopoda. The order also includes hippopotamuses and cetaceans under modern classifications that use the broader name Cetartiodactyla.

This group is often contrasted with Perissodactyla, the odd-toed order containing horses, rhinoceroses, and tapirs. The distinction is anatomical rather than simply visual: many artiodactyls have paired hoof halves, while perissodactyls generally emphasize a central toe.

One surprising neighboring fact is that whales and dolphins are artiodactyl relatives. Molecular evidence places cetaceans within the even-toed ungulate family tree, making Artiodactyla much broader than the familiar land animals listed in the question. Domestic cattle, pigs, camels, and their relatives have also helped spread the group across the world.