T. Rex Was a Coward at Times

We think of T. rex as the king of dinosaurs, instilling terror into everything around it. But that wasn't necessarily so. In this scene from the TV series Prehistoric Planet, we see a Tyrannosaurus rex munching on the carcass of a  sauropod dinosaur. But when he's confronted by a 20-foot-tall pterosaur species called Quetzalcoatlus, he has to consider his own safety. Quetzalcoatlus isn't as massive or as strong as the T. rex, but he sure is pointy. But how do scientists know what would have happened in such a scenario? It's a combination of anatomical studies of those species, plus knowledge of how predators of many different existent species behave. Dinosaurs may not have had large brains, but they knew how to calculate their odds well enough, or they wouldn't have survived as long as they did. Read an explanation of how this scenario was determined at BBC Science Focus. (via Real Clear Science)