The various dinosaur groups share some additional features that ornithosuchids lack. one is the loosening up and loss of the fuIl collarbone (clavicle-interclavicle) brace. This frees up the shoulder girdle so it can rotate and increase the step length of the forelimb. (Animatronic dinosaur)Another is an even deeper hip socket and a fully erect hind limb.
Dinosaurs and birds were long thought to have evolved as three or more separate groups from differing thecodonts, and were usually split into two hip types, the differences centering around the pubis, which projects below the hips. (Walking dinosaur costume for sale) The “reptilehipped” Saurischia, including the herbivorous prosauropods and brontosaurs along with the predatory theropods, had vertical pubes, while the “bird-hipped” herbivorous Ornithischia were those dinosaurs that had backward-pointing pubes. This theory started coming unglued in1974 when John Ostrom showed that birds were most like theropods, and Robert Bakker and Peter Galton pointed out that as a whole, dinosaurs are united by a number of key characters. Today a consensus tunong a number, but not all, of dinosaurologists supports this view, myself among them.a Among the more important of these key dino-bird characters is the strongly S-curved neck for down and forward plunges of the head. Other dino-bird uniSring features include enlarged preorbital depressions, slender bones in the roof of the mouth, fulty erect arms with more downward-facing shoulder joints, deeply rylindricat hip joints, larger knee crests, inner shank bones (tibias) that back a tall process of the ankle’s astragalus, (realistic dinosaur costume)transversely compressed cannon bones, and an outer toe that is always reduced. This suite of characters is a solid one, and it clearly separates dinosaurs and birds from all other four-limbed vertebrates, or tetrapods. It is possible that different groups evolved these traits independently, but the fact is that there is no good evidence that they did so. Just the opposite. The evidence strongly indicates that these traits form a true monophyletic clade.