RUMINANTIA

The biological suborder 'Ruminantia' includes many of the well-known large grazing or browsing mammals: among them cattle, goats, sheep, deer, and antelope. All members of the Ruminantia are ruminants: they digest food in two steps, chewing and swallowing in the normal way to begin with, and then regurgitating the semi-digested cud to re-chew it and thus extract the maximum possible food value.
Note that not all ruminants belong to the Ruminantia. Camels and llamas are among the exceptions. Also, there are a number of other large grazing mammals that, while not strictly ruminants, have similar adaptations for surviving on large quantities of low-grade food. Kangaroos and horses are examples.

★ 'ORDER ARTIODACTYLA'

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★ Suborder Suina: pigs, hippos and peccaries

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★ Suborder Tylopoda: camels and llamas

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★ 'Suborder Ruminantia'

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★ Family †Amphimerycidae

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★ Infraorder Tragulina (paraphyletic)

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★ Family †Prodremotheriidae

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★ Family †Hypertragulidae

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★ Family †Praetragulidae

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★ Family Tragulidae: chevrotains, 6 living species in 4 genera

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★ Family †Leptomerycidae

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★ Family †Archaeomerycidae

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★ Family †Lophiomerycidae

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★ Infraorder Pecora

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★ Family Moschidae: musk deer, 4 living species in one genus

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★ Family Cervidae: deer, 43 living species in 16 genera

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★ Family Giraffidae: giraffe and okapi, 2 living species in 2 genera

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★ Family Antilocapridae: pronghorn, one living species in one genus

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★ Family Bovidae: cattle, goats, sheep, and antelope, 131 living species in 51 genera