Ornithopod

Ornithopoda
Temporal range: Lower JurassicUpper Cretaceous
Ornithopods jconway.jpg
Ornithopod dinosaurs. Far left: Camptosaurus
left: Iguanodon, centre: Shantungosaurus
centre foreground: Dryosaurus, right: Corythosaurus, far right: Tenontosaurus.
Scientific classification
Kingdom:Animalia
Phylum:Chordata
Class:Sauropsida
Superorder:Dinosauria
Order:Ornithischia
Suborder:Cerapoda
Infraorder:Ornithopoda
Marsh, 1881
Three-toed feet of Iguanodon

Ornithopods are the infraorder of bird-hipped dinosaurs. They started out as small, bipedal running grazers, and grew in size and numbers until they became one of the most successful groups of herbivores in the Cretaceous world.

Their major evolutionary advantage was the progressive development of a chewing apparatus that became the most sophisticated ever developed by a reptile. They had beaks, multiple teeth rows, cheek pouches and true chewing.[1] Efficient chewing means faster digestion, as the material is broken into smaller pieces.

They reached their apex in the duck-bills, before they were wiped out by the Cretaceous–Tertiary extinction event with all other non-avian dinosaurs. Members are known from all seven continents, although the Antarctic remains are unnamed, and they are generally rare in the Southern Hemisphere.

They are the sister group to the horned dinosaurs (Ceratopsia) and the hard-headed dinosaurs (Pachycephalosauria).

Description

Ornithopoda means "bird feet", from the Greek. It refers to their three-toed feet (though many early forms had four toes). They had no armour, a horny beak, and various other features. Some ornithopods and cerapods had thin cartilaginous plates along the outside of the ribs. In some cases, these plates mineralized and so were fossilized. The function of these plates is unknown.[2][3]

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日本語: 鳥脚類
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русский: Орнитоподы
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татарча/tatarça: Орнитоподлар
українська: Орнітоподи
Tiếng Việt: Khủng long chân chim
中文: 鳥腳亞目