Final answer:
True, substantial evidence exists to suggest that endothermy existed among the early reptile lineages.
Step-by-step explanation:
True, substantial evidence exists to suggest that endothermy existed among the early reptile lineages.
While most reptiles are ectotherms, there are exceptions, such as crocodilians, which maintain elevated thoracic temperatures and appear to be at least regional endotherms. Endothermy, or the ability to regulate body temperature from within, evolved in mammals and birds, which descended from reptile-like ancestors.
Reptiles, on the other hand, are ectotherms and rely on behavioral adaptations to regulate body temperature, such as basking in the sun or finding shade. They can survive on a significantly lower calorie intake compared to endotherms.