STL Science Center

STL Science Center

21 June 2014

The Dinosaur or The Bird

©Emily Willoughby
Deinonychus was, and continues to be, a very important dinosaur in the "dinosaur renaissance" that is still ongoing as well as the ever growing list of evidence that birds and dinosaurs are related. The anatomy of Deinonychus actually began to be described many years prior to Ostrom's work on the dinosaur. A tooth was included in a description under a tentative name (Daptosaurus agilis) by Barnum Brown in 1931 while working on Tenontosaurus. Ostrom named the animal properly as Deinonychus antirrhopus, meaning Terrible Claw and "counterbalanced" (referencing the stiffened tail) in his 1969 description. That description is enormously detailed and meticulous. The Yale Peabody Museum keeps a copy of this description available online and it is well worth the read for anyone interested in anatomy and dinosaurs. It is also of interest to anyone interested in birds. Ostrom describes a number of bones discovered in Deinonychus that are very similar to those of birds, particularly in the forelimbs and pectoral  girdle (not that this is news to dinosaur and bird enthusiasts both at this point). In looking at these skeletal elements and the potential agility of these dinosaurs Ostrom also saw the potential for a warm-blooded animal. Not all paleontologists have always thought of dinosaurs as cold-blooded, but Deinonychus itself, Ostrom and Bakker's conviction to the idea, and more advanced knowledge and testing of fossils melded together to form the foundations of the "dinosaur renaissance". Part of the evidence rested in the agility of the skeleton and the active lifestyle that this dinosaur appears to have been the first evidence used by Ostrom to suggest warm-bloodedness.

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