Were dinosaurs cold-blooded or warm-blooded? This is a question that puzzles a lot of scientists. Warm-blooded is another term for endothermic, which means the animal is able to keep a fairly even body temperature without having to worry about the weather.
Mammals, including humans, and birds are the endothermic animals alive today.
Cold-blooded, or exothermic, means the animal does not produce heat inside its body. It has to sit in the sun to warm up or sit in the shade to cool down - the weather is very important to exothermic animals. Reptiles are the exothermic animals still alive today.
Endothermic animals produce body heat, which means they have to eat more food and can move quickly at any time of the day.
Exothermic animals do not need as much food since they do not produce body heat, which also means they can be very sluggish on a cold day.
A big animal like a dinosaur would require a lot of food to live. Even if it were exothermic, it would still require a lot of food. Some dinosaurs are huge but have very small mouths and it is a mystery as to how they ate enough to stay alive.
If dinosaurs were endothermic, they would need even more food, which is even more puzzling. Some dinosaurs seemed to live in cold environments.