Question: Were dinosaurs warm-blooded?

Amy Birch answered on 19 Jun 2012:

Hi meg123,
Another great question and again, scientists are still debating about this!
Most scientists used to believe that all dinosaurs were cold-blooded because they have something called ‘lines of arrested growth’ (or LAG), which means that whether they grew bigger depended on what season it was, so they could only grow when it was warm. Modern cold-blooded animals also have LAG, so it made sense to scientists that dinosaurs were cold-blooded too.

However, there is a lot of recent evidence that makes some scientists argue that dinosaurs could have been warm-blooded. Dinosaurs were built to run very fast and this would have taken a lot more energy so they would need to produce it themselves. Also many dinosaurs had brains that are larger than would be expected from a cold-blooded animal of that size and the brain uses a lot of energy so they would have needed to produce it themselves. Many dinosaur fossils have been found in places that would have been very cold as well, so they may not have survived if they were cold-blooded.

What do you think? I think that it is very likely that some dinosaurs were warm-blooded, especially because they are the ancestors of birds, and birds are warm-blooded. But maybe being warm-blooded evolved in some dinosaurs and not others…I guess we won’t know unless we went back in time & found out!