Saurischia

Dinosauria
Template:Regnum: Animalia Template:Phylum: Chordata Template:Classis: Reptilia Template:Superordo: Dinosauria Template:Ordo: Saurischia
Suborders
Suborder Sauropoda Suborder Theropoda

Saurischia pelvis structure

Saurischians (from the Greek Saurischia meaning lizard hip) are one of the two branches of dinosaurs. They are distinguished from the Ornithischians by retaining the ancestral configuration of bones in the hip. All carnivorous dinosaurs (the Theropods) are members of the Saurischians, as are all sauropods.

The Saurischians were diferentiated from the Ornithischians in the Late Triassic. The Ornithischians evolved a new hip structure, with the Pubis rotating to become parallel with the Ischium. This hip structure is similar to that of birds, and so Ornithischians are termed bird-hipped dinosaurs, while Saurischians are lizard-hipped. Later Saurischians of the Theropod Family evolved bird-like hips in the Jurassic. One branch of these evolved into birds. Thus, ironically, the lizard-hipped dinosaurs became birds.

The Saurischians suffered a major extinction at the end of the Cretaceous, and all non-avian forms became extinct.