Channels, Spring 2018

Page 72 Oldham • A Four-Legged Megalosaurus Ostrom would soon throw another wrench into the debate with the description of Deinonychus in 1969. The skeleton of the creature was very similar to that of a bird with its hollow bones, and it had very strange foot. The foot had two toes that would touch the surface of the ground while the third was like a sickle and retracted from the ground. He said this about the foot, The foot of Deinonychus perhaps the most revealing bit of anatomical evidence pertaining to dinosaurian habits and must have been anything but “reptilian” in its behavior, responses and way of life. It must have been a fleet-footed, highly predaceous, extremely agile and very active animal, sensitive to many stimuli and quick in its responses. These in turn indicate an unusual level of activity for a reptile and suggest an unusually high metabolic rate. The evidence for these lie chiefly, but not entirely, in the pes. (1969 cited by Desmond, 1990) The foot of this “terrible claw” seemed to suggest that the animal had an active lifestyle. Having an active lifestyle meant that it was probably endothermic, and the animal had a strange resemblance to bird. Ostrom compared the skeleton of birds like the Hoatzin and the chimera Archaeopteryx to Deinonychus. The hands had very similar features, including the same homology of digits and very similar wrists. Ostrom stated, 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. (Bakker, 1986 pg. 312) With Deinonychus Ostrom concluded that dinosaurs were more closely related to birds. A relationship with birds meant that dinosaurs were possibly endothermic as well. Ostrom’s work with hadrosaurs and Deinonychus injected a new fervor into dinosaurian paleontology. His work paved the way for his protégé, Robert Bakker, and others to make bold claims about the nature of dinosaurs. The Dinosaur Renaissance: A Scientific Revolution From Cuvier to the present, out of all the paradigm shifts only one led to a true scientific revolution within dinosaur paleontology. In order to prove his paradigm correct, Ostrom had to “attract an enduring group of adherents from competing modes of scientific activity. (Kuhn, 1970 pg. 10)” Ostrom saw what Kuhn would call anomalies in how dinosaurs were viewed. They were seen as nothing more than overgrown reptiles spending most of their time in aquatic environments. Ostrom recognized that dinosaurs like hadrosaurs had anatomical characteristics perfect for terrestrial locomotion. He also correlated the depositional environments and flora found within the strata to the lives of those dinosaurs. For Ostrom, the “orthodox view” of dinosaurs did not follow lines of evidence found in the geologic record. Also, with the discovery of Deinonychus with its very bird-like skeleton proved that dinosaurs were related to birds. As a result of this relationship, they were probably endothermic. His arguments did start a crisis within dinosaur paleontology. Kuhn