Why Dinosaurs Are Endotherms

Dinosaurs Were Endotherms
Jiawei Tan, 30120159

Abstract:

Whether dinosaurs were warm-blooded or cold-blooded is one of the most heated controversies since 19th century. This article is to suggest that dinosaurs were endotherms, which means they were warm-blooded. In this paper, I will list some evidences that indicate dinosaurs were more similar to mammals and birds rather than cold-blooded animals, such as reptiles. Evidences will be shown with comparison among dinosaurs, warm-blooded animals and cold-blooded animals. Thus, conclusion will be drawn to suggest that dinosaur were more likely to be endotherms. Introduction: Dinosaurs, as dominating animals in the Mesozoic Era and were extinct at the end of Mesozoic, raised a heated debate
Animals like polar bears and penguins, can survive because they are endotherms and can keep their body temperature at a certain temperature. According to the research by Rich et al. (2002), almost no ectotherms’ fossils found at polar latitude, but dinosaurs’ fossils were found in the Arctic. Conspicuously, cold-blooded animals like lizards and crocodilians, are not seen at such high latitudes. Ectotherms highly rely on the surrounding temperature to keep active. Although the research mentioned that the weather at the time was not as extremely cold as that in polar latitudes, ectotherms like crocodilians cannot survive at that time inside polar areas. Like polar animals, such as polar bears and penguins, dinosaurs probably had an ability to produce heat and keep body temperature at a certain temperature to survive under the extreme cold weather. It indicates that dinosaurs should be endotherms in order to have the ability to produce
In bipedal dinosaurs and erect-limbs dinosaurs, were required to generate more energy to support their movement (Herman, Vivian & John, 2009). In the research, it showed that the requirement estimated for locomotor power at hip height was above the capabilities of ectotherms, when dinosaurs were running at moderate speeds. It also showed that it needed high output of metabolism in some enormous dinosaurs even just for walking. Since that, it requires a high rate of metabolism to produce heat and energy. Also, it was found that nearly all animals, which walked upright, were endotherms (Bakker & Robert, 1986). However, many ectotherms, like crocodiles and tortoises that had sprawling limbs, did not have high rate of metabolism because sprawling prohibited them to move and respired together (Carrier,