Ornithischia
| Ornithischia | |
|---|---|
| Scientific classification | |
| Kingdom Information | |
| Domain | Eukaryota |
| Kingdom | Animalia |
| Subkingdom | Bilateria |
| Branch | Deuterostomia |
| Phylum Information | |
| Phylum | Chordata |
| Sub-phylum | Vertebrata |
| Infraphylum | Gnathostomata |
| Class Information | |
| Superclass | Tetrapoda |
| Class | Reptilia |
| Infra-class | Archosauromorpha |
| Order Information | |
| Superorder | Dinosauria |
| Order | Ornithischia |
| Population statistics | |
| Conservation status | Extinct |
Ornithischia or Predentata is one of two major orders of dinosaurs, and includes both bipedal and quadrupedal herbivorous animals, all of which share a pelvic structure similar to that of birds.
Description
The primary characteristic is the pelvic girdle, comprised of ilium, the ischium, and the pubis. The process of the pubis points to the rear - as in birds - to allow for a long digestive tract. A further shared characteristic is the presence of a predentary bone at the tip of the lower jaw, hence the other name for the order.[1] All ornithischians also bear a beak due to the rostral tip of premaxilla being toothless.
Taxonomy
- Order Ornithischia
- Family Pisanosauridae
- Family Fabrosauridae
- Suborder Thyreophora
- Infraorder Ankylosauria - armored dinosaurs
- Family Ankylosauridae
- Family Nodosauridae
- Infraorder Scelidosauria - scute-armored dinosaurs
- Family Scutellosauridae
- Family Scutellosauridae
- Infraorder Stegosauria - plate-armored dinosaurs
- Family Huayangosauridae
- Family Stegosauridae
- Infraorder Ankylosauria - armored dinosaurs
- Suborder Cerapoda
- Family Heterodontosauridae
- Infraorder Ornithopoda - duck-billed dinosaurs
- Family Camptosauridae
- Family Dryosauridae
- Family Hadrosauridae
- Family Hypsilophodontidae
- Family Iguanodontidae
- Infraorder Hypsilophodontia - small ornithopod dinosaurs
- Family Hypsilophodontidae
- Family Tenontosauridae
- Family Thescelosauridae
- Infraorder Pachycephalosauria - bone-headed dinosaurs
- Family Pachycephalosauridae
- Infraorder Ceratopsia - horned dinosaurs
- Family Bagaceratopidae
- Family Ceratopsidae
- Family Chaoyangsauridae
- Family Protoceratopsidae
- Family Psittacosauridae
Due to head displays, some authorities accept the placement of the ceratopsid and pachycephalosaurid dinosaurs into the recently created suborder Marginocephalia.
Evolutionary claims
Birds are claimed by evolution to be descended from theropod dinosaurs of the other major order Saurischia, due to similar structures in the wrist; despite being different, the "lizard-hipped" pelvic girdle of saurischians is never mentioned as a factor in the ancestry of birds.
