If so, then big ectothermic polar dinosaurs may have had only one choice: to migrate south. In 1980, Walking dinosaur costume Nicholas Hotton built a grand theory of vast herds of sun-following dinosaurs pushing toward medium latitudes in the fall, then returning to the poles each spring. Ironically, this will not work for low-metabolic-rate animals. Imagine a 2.S-tonne theropod standing on the north slope of Alaska, or in southern Mid-Cretaceous Australia. Getting out measuring string and a globe, and taking into account detours around obstacles and the like, it turns out that our dinosaur would have to make a yearly roundtrip of 9000 or more km to reach latitude 55′ (Realistic dinosaur costume). That is equal to a walk from New York to Los Angeles and back! As a standard ectotherm, the 2.S-tonne theropod would have a metabolic rate of about 1,900,000 kcaVyear (Appendix A). It would cost the same theropod about 11,000,000 kcal to walk 9000 km a year, many times its yearly ectothermic energy budget. Animatronic dinosaur Large, low-metabolic-rate polar theropods would have been in a bind. Unable to tolerate the polar winter, it does not look like they had enough energy to follow Mark TWain’s advice that if you do not like the weather, move.20
Of course the whole problem disappears if dinosaurs had high metabolic rates. Dinosaur suit With energetics ten times as great, they could have migrated such long distances; a few humans have walked cross country. Or they could have weathered the polar winter. At first it seems that bulk endothermy would work as well for polar theropods as would an avian-mammalian system. After all, the big ones would have high metabolic rates, and small species could hibernate. But this does not really work, because the low-metabolic-rate juveniles of big-bulk endotherms would be unable to keep up with their parents during the migration because of their lack of energy. Nor could they hibernate, because the social dinosaur’s young has to stay with the active adults.2t In the end, only avian-mammalian physiologies offer a full explanation of polar theropods.