This is a really fascinating thing, for these animals are no longer truly homeothermic. Walking dinosaur costume They are hypertherms, letting their body temperature rise to cope with extreme heat and drought. Animatronic dinosaur Brains are kept cool by “counter-cument” heat exchange systems in the blood vessels. So, far from being a barrier to high metabolic rates, the large size of many theropods may have been an adaptation for being endothermic in hot, seasonally dry climates.
So, we now see that a key argument for a theropodian physiology of the reptilian Vpe, the large size of many species, works just as well if they were ful1 endotherms. This means that the suggestion by Hotton and others that dinosaurs tended to be big for bulk and other myt’ is neutrahzed. Besides, as explained in Chapter 3, theropods had a hard time being really small because of their stiff-action limb design. mechanical dinosaur
There is yet another body-size-related factor that supposedly favors theropod ectothermy. Realistic dinosaur costume As certain therapsids evolved into mammals, they went through a “size squeeze”-i.e., the first mammals were quite small, the size of shrews and mice. Likewise, the first birds, such as Archaeopterq, were exceptionally small. There are arguments that full-blown mammalian-avian endothermy can evolve only during such size squeezes.23 Dinosaurs, being large, supposedly do not fit this criterion. This is a rickety anti-endothermy argument. We do not reolly know if animals have to go through a size squeeze to become full endotherms; it is only a theory. Even worse, early dinosaurs did go through such a size squeeze. Protodinosaurs such as predatory Lagosuchus were tiny fellows, smaller than the first birds.