Tooth by deadly tooth, dinosaurs with a hunger for meat bit using four basic techniques, with strength sacrificed for speed and vice versa, new research finds.
Carnivorous dinosaurs ranged from weak yet fast nippers, like Velociraptor, to strong and efficient biters, such as Tyrannosaurus rex.
Tyrannosaurs, allosaurs, ceratosaurs, and parrot-like dinosaurs, such as Citipati, inflicted the most damaging, efficient bites, the new research suggests. These dinosaurs didn't even have many teeth, compared to certain other dinos. But the teeth they possessed did the job well, like ripping the heads off of prey.
"These dinosaurs have consistently high efficiency in biting along the entirety of their relatively short tooth rows," said Manabu Sakamoto, author of the study, published in the latest Proceedings of the Royal Society B. Sakamoto is a researcher in the Department of Earth Sciences at the University of Bristol.
To determine the biting strength of carnivorous dinosaurs, he calculated the ratio of the muscle force and biting force, together known as the "mechanical advantage," for several meat-eating species. He did this for each biting position along the tooth rows present in a particular dinosaur's jaws.
Sakamoto discovered that the most primitive type of biting belonged to dinosaurs such as Herrerasaurus, Carcharodontosaurus, and Ceratosaurus. Their back teeth did much of the work.
One of the most bizarre biting styles belonged to the coelophysoid dinosaurs: Coelophysis and Syntarsus. They could bite with a great deal of force at the back of their mouths, but their front teeth were limited to a really weak and fast bite.
The final type of carnivorous dino bite belonged to what Sakamoto called "the ostrich-like dinosaurs," such as Velociraptor.
"These dinosaurs have consistently low efficient biting across their tooth rows so they have relatively weak bites," he said. "But, in effect, this also means that they have relatively fast biting speeds."
He added that Archaeopteryx, the world's oldest known bird, also bit in this Velociraptor manner.
Another component of the study involved testing whether or not closely related dinosaurs bit in similar ways. For the most part, this was true, providing evidence that the various biting styles were inherited, evolved behaviors.
There were a few exceptions to the rule, however. Oviraptorosaurs — known for their parrot-like skulls — and therizinosaurs — that looked like a cross between a big sloth, lizard and bird — did not have predictable biting styles based on family history. Although their relatives were weak yet fast biters, oviraptorosaurs and therizinosaurs were highly efficient, strong biters.
"A possible explanation is that the ancestral stock of this group underwent adaptive evolution and filled an open ecological and functional niche," said Sakamoto.
Other research suggests that if meat-hungry dinosaurs were alive today, they would be among the world's strongest biters.
Stephen Wroe of the University of South Wales recently reported that the bite force of T. rex was 3.1 tons, which is more powerful than the bite of a great white shark. Great white sharks, in turn, bite 20 times harder than humans can.
But Wroe believes the most formidable carnivore and biter to have ever lived was the now-extinct shark Carcharodon megalodon, otherwise known as "Big Tooth." According to his analysis, it could generate up to 18.2 tons of bite force, and was at least 30 times as heavy as today's largest great whites.