Heilmann’s theory required parallel evolution in unusually large doses, far larger doses than would be required even for the Tasmanian wolves.(dinosaur rides for park)Heilmann’s theory reigned as fact down into the 1960s. In 1964, John Ostrom at Yale discovered the very advanced predatory dinosaur Deinonychus, a long-armed Early Cretaceous carnivore with a cruel-looking killing claw on its hind foot. Ostrom spent two years carefully analyzing Deinonychus’s place among the meat-eating dinosaurs. Unknowingly he was being led directly to the final and correct solution of the mystery of the origin of birds. Biomechanical analysis applied to Deinonychus’s bodily configuration yielded evidence for exceptionally high levels of locomotive activity: both running speed and maneuverability. (dinosaur factory)Quite clearly, Deinonychus had had a great deal of birdness built into its limbs, a birdness that would have expressed itself in life by a daily metabolic regime more fitting for a ground bird such as a cassowary than for the orthodox view of any cold-blooded dinosaur.
After completing his monograph on Deinonychus, Ostrom planned for his next project – a study of pterodactyls. His two projects, the first on Deinonychus, the second on pterodactyls, seemed totally separate endeavors, and neither appeared to have anything at all to do with the origin of birds. Yet his investigation of pterodactyls was destined to lead John Ostrom to the discovery of a new fossil.(dinosaur costume)And that would lead him directly to the dinosaur that was the true ancestor of all birds.