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| Even-toed ungulates
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Mountain Goat | ||||||||
| Scientific classification | ||||||||
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Suidae Hippopotamidae Tayassuidae Camelidae Tragulidae Moschidae Cervidae Giraffidae Antilocapridae Bovidae
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As with many mammal groups, even-toed ungulates first appeared during the early EoceneThe Eocene epoch (55-37 mya) is a major division of the geologic timescale and the second epoch of the Tertiary period in the Cenozoic era. The Eocene spans the time from the end of the Paleocene epoch to the beginning of the Oligocene epoch. The start of (about 54 million years ago). In form they were rather like today's chevrotainChevrotains : Animalia : Chordata : Mammalia : Artiodactyla Tragulidae The four species of chevrotain also known as mouse deer make up the family Tragulidae . Chevrotains are small, secretive creatures, now found only in the tropical forests of Africa, Ins: small, short-legged creatures that ate leaves and the soft parts of plants. By the late Eocene (46 million years ago), the three modern suborders had already developed: SuinaSuina : Animalia : Chordata : Mammalia : Artiodactyla Suina Families Suidae Tayassuidae Hippopotamidae The Suina contains the earliest and most archaic Artiodactyla. There are three families alive today: Family Suidae ( pigs) Family Tayassuidae ( peccarie (the pig group); Tylopoda (the camel group); and Ruminantia (the goat and cattle group). Nevertheless, artiodactyls were far from dominant at that time: the odd-toed ungulates (ancestors of today's horses and rhinos) were much more successful and far more numerous. Even-toed ungulates survived in niche roles, usually occupying marginal habitats, and it is presumably at that time that they developed their complex digestive systems, which allowed them to survive on lower-grade feed.
The arrival of grasses during the Miocene (about 20 million years ago) saw a major change: grasses are very difficult to digest and the even-toed ungulates with their highly-developed stomachs were better able to adapt to this coarse, low-nutrition diet, and soon replaced the odd-toed ungulates as the dominant terrestrial herbivores.
The artiodactyls fall into two groups which, despite underlying similarities, are rather different. The suoids (pigs, hippos, and peccaries) retain four toes, have simpler molars, short legs, and their canine teeth are often enlarged to form tusks. In general, they are omnivores and have a simple stomach. (The two hippopotamus species are exceptions.)
The camelids and the Ruminantia, on the other hand, tend to be longer-legged, to have only two toes, to have more complex cheek teeth well-suited to grinding up tough grasses, and multi-chambered stomachs. Not only are their digestive systems highly developed, they have also evolved the habit of chewing cud: regurgitating part-digested food to chew it again and extract the maximum possible benefit from it.
Lastly a group of artiodactyls, which molecular biology suggests were most closely related to Hippopotamidae, returned to the sea to become whales.
All kosher mammals are Ruminantia. Tylopoda walk on pads on the toes (the name means "padfoot") and are therefore considered not to have true hooves; but they are halal. Pigs do not ruminate and are considered unclean by both Judaism and Islam.
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