THE SAURISCHIA ("REPTILE-HIPPED" DINOSAURS)
In this type of hip, one of the three main bones, the pubis, points forwards. This hip structure is found in several carnivores, such as the Velociraptor, and large dinosaurs. Saurischian dinosaurs also include very large land dinosaurs.
THE ORNITHISCHIA ("BIRD-HIPPED" DINOSAURS)
In this hip structure, the pubis points backwards, and seems to "hug" the ischium. This gives the more pointed bird-like structure for the dinosaurs. All of these dinosaurs are herbivores: "duck-billed" herbivores, horned herbivores (such as the Triceratops), large herbivores (such as the Stegosaurus), and clubbed herbivores.
See also the phylogeny of dinosaurs. A button can be found at the top of the genetics page to teleport you there.