ned to maximize the opportunities presented by their environments. One of the most controversial aspects of dinosaurs is the method by which they regulated body temperature.
Conventional wisdom viewed dinosaurs as reptiles, thus they were considered ectotherms. However, as new discoveries became apparent, many began to view at least some dinosaurs as endothermic creatures. Robert Bakker originated a series of papers during the 70s and 80s that claimed “endothermy was the only possible regulatory regime which dinosaurs could have utilized and still maintained their ecological dominance” (58). Two paleontologists have helped fuel the ectotherm/endotherm debate with studies focusing on the skeletal remains of a Tyrannosaurus Rex. Using oxygen isotopic composition of bone phosphate to calculate the body temperature variability of the T. Rex, Barrick and Showers concluded: “Vertebrate bone phosphate is a function of the body temperature at which bone forms and of the isotopic composition of the body water. The isotopic composition of body water depends on the water ingested during feeding and drinking as well as on the metabolic rate relative to water turnover rates”,(222).
The results of the above research have been vehemently criticized by those supporting ectothermic temperature regulations in Dinosaurs. However, the compelling results fit in with some other theories regarding Dinosaur existence. For example, large mammals began to appear before the dinosaurs became extinct. This indicates that dinosaurs, which held their own against such mammals, most likely had an active metabolism or the rise of large body sized mammals would not have begun until after
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