Theropoda

From EvoWiki

Allosaurus (IPA pronunciation: /ˌæləˈsɔɹəs/) is a genus of large (up to 9.7 m long) theropod dinosaurs that thrived in the Jurassic period.

Theropoda ("Beast foot"; Marsh, 1881 sensu Gauthier 1986) are a group of bipedial, mainly carnivorous dinosaurs, and are the common ancestor of, and all descendants of forms closer to Neornithes, than Saltasaurus, making them the ancestors of all birds. The group included Tyrannosaurus rex, the dromaeosaurs, including Velociraptor and Deinonychus, the herbivorous ornithomimids and oviraptorosaurs. The group flourished during the Triassic, but is today only represented by birds.

Anatomy

The list of autapomorphic characters underwriting holophyly of Theropoda is substantial (from Gauthier 1986, and Weishampel et al. 1990):

1. Lacrimal broadly exposed on the roof of the skull
2. Accessory fenestra present within the antorbital fossa
3. Vomers fused rostrally
4. Ectopterygoid expanded and concave in ventral aspect
5. Presacral vertebrae pleurocoelous
6. Sacrum includes at least five vertebrae
7. Manus has reduced or absent metacarpal/digit IV, V
8. Ilium possesses a distinct brevis fossa
9. Femur is bowed, but nearly nonsigmoidal
10. Fibula appressed to tibia along the length of the fibular crest
11. Metatarsal V reduced to a splint
12. First metatarsal separate from tarsus

JGK