Palaeontologists debate this for the following reasons:
- Dinosaurs are related to reptiles - reptiles are cold-blooded
- Dinosaurs are related to birds - birds are warm-blooded
- If Sauropods were warm-blooded, they would literally decimate the forests of the Late Jurassic - so they must be cold-blooded
- Raptors are very active animals - so they must be warm-blooded
These are just some reasons.