Predatory dinosaurs have been gone for 650,000 centuries, but that does not stop us from painting such pictures of how they made a living-how they hunted, how they spent their spare time, their social behavior, reproduction, and the like.1 We are able to do so by making deductions based on what we know about their structure and on the fossil records. In describing the life-styles of the predatory dinosaurs, I am going to work from a basic assumption that the dinosaurs were fully warm-blooded in the way birds and mammals are. As I explain in Chapter 7, I do not think the alternative physiologies are viable ones.Let us begin with the one feature that made most predatory dinosaurs what they were-killers-and that is their teeth. . Most typical theropods had long rows of sharp teeth* This tells us that they were predators-for herbivores simply do not have such teeth. The fact that they were predators in turn tells us something less obvious: that theropods enjoyed much more leisure time than do most humans, and spent most of it asleep. This is typical of medium sized and big predators-lions and even house cats for that matter spend up to twenty hours a day napping. Predators, especially those that kill big game, go out and kill something, eat it in one quick sitting, and then sleep it off until they are hungry again. As detailed in Appendix A, big predators can go for days or, in the case of giants, even weeks between meals. This is quite unlike herbivores, which must spend long hours nipping at and chewing large quantities of fodder* In fact, sleeping when there is nothing else to do has an important advantage. Bedding down helps keep an animal out of sight and out of trouble. This is especially true for small species and the juveniles of big ones, for big predators are very happy to attack and consume smaller predators.
But whatever amount of time they spent lazing about, predatory dinosaurs were built for those briefer but much more intense and interesting times-when they went off to kill and eat other animals. Killing big animals requires firepower, and in animals such power can only come from muscles. Mammalian carnivores of today have oversized neck muscles which give them tremendous biting power, something our household pets can demonstrate. Feel the neck muscles of a big dog and compare them to your own. Likewise, the heads of most predaceous dinosaurs were packed with powerful jaw-closing muscles (animatronic dinosaur), and their neck muscles were well developed, further increasing the available killing power.