DINOSAUR CONTROVERSIESA number of interesting mysteries surrounding the "terrible lizards" remain the source of ongoing controversy. These include the discussion of whether the mighty carnivore T-Rex was a ferocious hunter or merely a lumbering scavenger. Some debate whether the large herbivorous dinosaurs like Diploducus and Brachiosaurus could have raised their heads as they are commonly depicted. A major source of controversy surrounds the traditional belief that dinosaurs were "cold-blooded." Some would point to evidence suggesting certain dinosaurs were warm-blooded, active pack hunters. Others counter that even though dinosaurs were cold-blooded, their generally immense size would have maintained a body temperature permitting them to be agile and active. Some puzzles (like how the large pterosaurs flew) are solved by understanding how the conditions were different on the early earth.