Was t-rex cold blooded or warm blooded?

Answer 1

It is not certain, as we have only fossilized bones which tell us little about dinosaurs' soft tissues and organs which we would need to determine warm-/cold-bloodedness, but generally assumed that dinosaurs were, like modern reptiles, cold-blooded.

However, it has been recently discovered that at least some dinosaurs had live births, which is very surprising because it is most definitely not a trait of modern reptiles (modern reptiles lay eggs that hatch and do not have live births); this may lead to increased doubt over whether dinosaurs had many traits in common with modern reptiles, including being cold-blooded. Two groups of warm-blooded animals, mammals and birds, are descended from dinosaurs.