Gigantotheria

Gigantotheria is a hypothesis that explains how large, cold-blooded animals like dinosaurs could have maintained high body temperatures in cooler climates. The theory suggests that body size alone could have provided sufficient thermal inertia to keep their internal temperature relatively stable, even without the metabolic heat production of endothermy (warm-bloodedness). Essentially, a large body retains heat much better than a small one due to a lower surface area to volume ratio. This would have allowed them to absorb heat from their environment and maintain a warm core temperature for extended periods, similar to how a large rock retains heat on a sunny day.

The concept of gigantothermy was proposed as an alternative explanation for the warm-bloodedness observed in many extinct reptiles, particularly dinosaurs. It posits that instead of necessarily being metabolically warm-blooded, their massive size was the primary factor in thermoregulation. This would have been advantageous in environments with fluctuating temperatures or those that were generally cooler than tropical regions. While not mutually exclusive with some degree of endothermy, gigantothermy offers a plausible mechanism for achieving high body temperatures without relying solely on a high metabolic rate. It remains a significant concept in paleontology when discussing the physiology and ecological capabilities of extinct megafauna.