Ornithischia
| Ornithischia Temporal range: Upper Triassic–Upper Cretaceous, 228–65 mya |
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| Ornithischian pelvic structure (left side) | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Sauropsida |
| Superorder: | Dinosauria |
| Order: | Ornithischia Seeley, 1888 |
Ornithischia is an order of beaked, herbivorous dinosaurs. The name ornithischia is derived from the Greek ornithos meaning 'of a bird' and ischion meaning 'hip joint'. They are known as the 'bird-hipped' dinosaurs because of their bird-like hip structure, even though birds actually descended from the 'lizard-hipped' dinosaurs, the Saurischia.
The ornithischia has two sub-orders:
- Thyreophora: the armoured dinosaurs: Ankylosaurs and Stegosaurs.
- Cerapoda: the duck-billed and horned dinosaurs.
The predentary is an extra bone in the front of the lower jaw, the dentary. The predentary coincides with the premaxilla in the upper jaw. Together they form a beak-like apparatus used to clip off plant material.
Their basal form of locomotion was bipedal. However, from early in their evolutionary history, they capable of both bipedal and quadrupedal locomotion.[1] Several groups became entirely quadrupedal.
