Final answer:
No, all dinosaurs were not ectotherms. Some fossil evidence suggests that dinosaurs that were the immediate ancestors to birds were likely endothermic, or warm-blooded, like modern birds.
Step-by-step explanation:
No, all dinosaurs were not ectotherms. Most reptiles, including some dinosaurs, are ectotherms, meaning their body temperature is regulated by the environment. However, it is not known with certainty whether all dinosaurs were ectotherms. Some fossil evidence suggests that dinosaurs that were the immediate ancestors to birds were likely endothermic, or warm-blooded, like modern birds.
Ectothermy means regulating body temperature from the outside through behavioral changes, such as basking in the sun to warm up. On the other hand, endothermic animals can regulate their body temperature using heat produced by metabolism and muscle contraction.