Theropod Discovery Challenges the Dinosaur-to-Bird Theory :: Anthropology Essays Paleontology Papers

Theropod Discovery Challenges the Dinosaur-to-Bird Theory For years, it has been believed that Dinosaurs are ancestors of modern day birds. By simply looking at pictures of dinosaurs, one can find many physical similarities between these reptiles and modern day birds. Often the legs and the chest cavities are very similar in shape. Some dinosaurs have limbs that look like they could evolve into modern day wings, some dinosaurs even had feathers (6). A recent discovery in Italy of an extremely well preserved Scipionyx samniticus challenges this idea. The skeleton of this small Therapod was nearly complete, but more impressively, there was still remnants of soft tissue. Portions of the Trachea, the liver, the skeletal muscle, and the intestines were still preserved (1). Scipionyx is a small meat-eating dinosaur that lived in the early Cretaceous. It has sharp teeth and claws, with powerful hind legs. The fourth maxillary tooth is longer than the rest almost giving the Scipionyx a vampire-like look. It has a long tail that aided in its balance, very large eyes and was most likely a small, yet quick hunter (3). It lived in what is now Italy. The skeleton that was found was a nine inch newborn, but some scientists think that a full grown Scipionyx can reach up to ten feet in length (3). The Scipionyx also possess an enormous hand which is common to the maniraptors (3). This group includes dinosaurs like the velociraptor. The Scipionyx was so well preserved in limestone, that using an ultra-violet light, one could get almost an X-ray of the baby Therapod (5). The internal organs of this dinosaur are somewhat similar to that of a crocodile. For example, the Trachea is well situated in the vertebral column (1). In birds, the Tracheas is usually adjacent to the vertebral column. Similarly to the crocodile, the Scipionyx’s liver is placed ahead of the large intestine (1). The Scipionyx has small groups of muscle fibers that seem to be diaphragmatic musculature (1). Again, these are similar to that of modern day crocodiles. The diaphragmatic musculature aides in diaphragm assisted breathing, which allows modern-day crocodiles to have burst-like movements (1). These traits are not consistent with an avian style, air sac component which is typical of birds (1). The diaphragm was shown to divide the body into two parts. One part contained the heart and the lungs, the other had the intestines, and the entrails (2).