memes

Oh, you're no fun anymore.

In all seriousness, thanks for bringing up that concept. On the surface, we generally group animals into endotherms and exotherms, but the reality is much more diverse, as you pointed out. Certain species of Tuna do make it into the category of endotherm because they generate enough heat internally to make a significant difference, however their body temperature is still largely variable depending on the surrounding environment making them also poikilotherms. Whereas mammals and birds are generally endotherms and homeotherms. I'm skipping over the concepts of hibernation and torpor in our bear and hummingbird friends, respectively, because that's a whole other can of worms. In conclusion, I believe T. Rex, and many other dinosaurs, were both endotherms and homeotherms.