A new study by a group of scientists led by M. Grady of University of New Mexico suggests that Dinosaurs were neither cold blooded animals like the reptiles nor warm-blooded animals like mammals or birds. Instead, they were something in between like Tuna.
The worm blooded animals, endotherms, use internal energy to warm their bodies and have high metabolic rates. On the other hand the cold-blooded ectotherms have low metabolic rates and use the environment to regulate their body temperature. The rare third group called mesotherms burn energies to regulate their body heat, but not to a constant temperature like mammals. They go to a certain temperature above the surrounding environment.
The research group compiled a database of growth rates and metabolic rates in 381 animal species, including 21 dinosaurs. They found that mammals grew 10 times faster than the reptiles and their metabolic rates are 10 times faster than that of the reptiles. The dinosaurs show up midway along the scale.