I strongly suspect that polar theropods did not migrate very far. After all, no living terrestrial animal wanders anywhere near the distances involved. Walking dinosaur costume Even arctic caribou and polar bears move only 2500 km each year. Realistic dinosaur costume Today, caribou and musk oxen stick it out through vicious arctic winters, and the wolves and foxes that feed on them remain too. Surely the herbivorous endothermic dinosaurs could tolerate the much milder Cretaceous winters as well, if not better. And if the herbivorous dinosaurs stayed, the predatory species would have been there to prey on them. Dinosaur costume for sale It is even possible, though perhaps not necessar!, that big polar dinosaurs sported a winter coat of feather insulation. So we can envision a tyrannosaur under the arctic night, the moon low on the horizon and the ghostly aurora borealis overhead; its breath condenses in the cool damp air, its shuffling feet disturb the melting snow that has dusted the landscape. For those of us who live in high northern latitudes the image of winter dinosaurs is appealing, for it puts them in the crisp, late fall conditions we are familiar and comfortable with.
Quite different from the coolness of rainstorms and polar nights is the problem of big, overheqted theropods in sunny dry seasons. Walking dinosaur suit As animals increase in size, their surface area per kilogram gets smaller. The metabolic rate per kilogram declines too, but not as fast as the skin area. In effect, it is the very bulk of large animals that insulates them. Alas, this fact is misunderstood by most. They believe that since big animals are less able to dump excess heat through their skins, that they have a hard time keeping cool when the environment is hot. To avoid this quandary, it is argued that big dinosaurs had to have had low metabolic rates. This is another fallacious yet persistent truism, which has been disproved by modern physiologists such as Knut Schmidt-Nielsen and C. Richard Taylor. That this false theory has endured seems most strange when one realizes that all of the biggest living tropical animals (elephants and rhinos) have fast mammalian metabolisms, and there used to be far more glant mammals in the tropics than there are today.