Temporal range: Upper Triassic–Upper Cretaceous, 228–65 mya
|Ornithischian pelvic structure (left side)|
Ornithischia is an order of beaked, herbivorous dinosaurs. They are known as the 'bird-hipped' dinosaurs because of their hip structure. However, birds actually descended from the 'lizard-hipped' dinosaurs, the Saurischia.
An alternative name for the order is the Predentata, because all of them are beaked herbivorous dinosaurs. The beak is in front of the jaw-bone, the dentary, so it is a 'predentary'. The upper half of the beak is the 'premaxilla' on the end of the upper jaw. The beak is a key adaptation for cropping plants for their food.
Their original (basal) form of locomotion was bipedal. However, from early in their evolutionary history, they were capable of both bipedal and quadrupedal locomotion. Several groups became entirely quadrupedal.
The ornithischia has two sub-orders:
- Thyreophora: the armoured dinosaurs: Ankylosaurs and Stegosaurs.
- Cerapoda: the duck-billed and horned dinosaurs.
Ornithischia is a branch-based taxon defined as all dinosaurs more closely related to Triceratops horridus than to either Passer domesticus or Saltasaurus loricatus.
Ornithischia Facts for Kids. Kiddle Encyclopedia.