According to the theory of dinosaur extinction, what adaptation of mammals likely helped them survive?

The adaptation of endothermic body metabolism, or being warm-blooded, likely played a crucial role in the survival of mammals during the dinosaur extinction event. This metabolic trait allows mammals to maintain a stable internal body temperature regardless of the external environment. Such an advantage would have enabled them to thrive in the cooler, rapidly changing climates that followed the extinction of the dinosaurs, as competition for resources decreased and ecological niches were altered.

Additionally, endothermy helps organisms sustain higher levels of activity, allowing mammals to forage for food and evade predators more effectively compared to ectothermic organisms, which rely on external heat sources to regulate their body temperature. This adaptability could have been vital in a challenging environment with decreased sunlight and vegetation, making it more difficult for ectothermic animals to survive.

In contrast, while small body size, camouflage, and hibernation might confer advantages under certain circumstances, they do not specifically relate to the resilience mammals demonstrated in response to global climate shifts and resource changes following the extinction event.