An obvious difference between a carnivorous mammal and a theropod is seen in the form and function of the teeth. Predatory dinosaur teeth were not arrayed in the short sets of molars, canines, and incisors seen in modern cats and dogs (animatronic dinosaur). Dogs’ big, sharp, conical canines are used to puncture flesh; ca-nids and hyenas like to grab on to various parts of big prey and pull; weasels and cats deliver precision bites to vulnerable areas such as the base of the skull or the throat, and then use their complex slicing molars to cut up the meat. The predatory dino¬saur’s long rows of uniform, curved, flattened, serrated blades were very different, more akin to those of the modern predatory lizard. (The closest mammalian analogues were the extinct sabertoothed cats, which, recent research indicates, used a peculiar pinch-and-slash biting action.2) The key point is that most pre¬daceous dinosaurs were neither grabbers nor precision biters. The long, irregular tooth rows of the theropods were not suitable for precision work, and their bladelike teeth would have tended to slice or cut through the flesh of their prey rather than to hold tight. In fact, the serrations, which were on the keels on the front and back edge of the teeth, enhanced this slicing effect. A bit of often-repeated nonsense is that these teeth were as sharp-edged and pointed as steak knives. Actually, one can run one’s finger hard down the serrations with no adverse effects. But, powered by big jaw and neck muscles, the slicing perfor¬mance of these tooth rows was potent, The wounds they inflicted would have bled heavily and readily become infected. Limb muscles could have been sliced, crippling their prey. Or the belly could have been disem boweled-just as the giant Komodo monitors of modern day In donesia will cut open the bellies of oxen and deer.
The premaxillary teeth in the snout tip of Tyrannosaurus rex and its relatives had a somewhat different action. In many theropods these teeth were more D-shaped in cross section than the rest of the teeth, and they tended to cut out a small scoop of flesh. In tyrannosaurs the premaxillary teeth were fully D-shaped in cross section, with the flat of the D facing inward. Such teeth did not slice; instead, they cut out, like a trowel in dirt, or a cookie cutter. These D-cross-sectioned teeth were themselves arranged in an exceptionally broad, D-shaped, semicircular array at the front of the upper jaw, and were backed by slicing teeth behind them. They would have scooped out a long, deep chunk of flesh, leaving a great, trough-shaped hemor rhaging hole in the hapless victim’s sider- a diabolically nasty wound, and one rather like those made by some modern sharks.