麻豆传媒

A HUGE predatory dinosaur attacked its prey not by biting it, but by slashing
its flesh like a medieval knight wielding a mace. Allosaurus slammed
its upper jaw into its victims, ripping off flesh with its sharp teeth, says
Emily Rayfield of the University of Cambridge. Komodo dragons also use the
slash-and-tear method.

Palaeontologists believe the jaws of the massive Tyrannosaurus rex
were so powerful they could crush bones. Even though Allosaurus lived
in the late Jurassic, some 85 million years earlier than T. rex, it
left more fossils. But it has not been studied in much detail.

When Rayfield looked at its jaw muscles, she found 鈥渢he bite of
Allosaurus is by no means pathetic, but by no means as big as modern
predators like lions.鈥� It was only about a quarter as strong as T. rex鈥檚
bite or a modern crocodile鈥檚.

Trying to understand the comparatively weak bite, Rayfield created a computer
model of the skull of 鈥淏ig Al鈥�, an allosaur fossil from Wyoming, and calculated
the force that its jaws would need to break the skull of a living animal. The
allosaur skull is lighter and has more openings than that of T. rex,
but structural engineering analysis showed that it was many times stronger than
necessary to withstand biting forces.

The combination of the weak bite and the strong light skull led her to
conclude that Allosaurus had a different feeding strategy, perhaps
opening its jaws wide and slamming the upper jaw into its prey.

鈥淚t鈥檚 not what I would have expected, but it seems to fit the evidence in
general,鈥� says Tom Holtz, a dinosaur palaeontologist at the University of
Maryland in College Park. He points out that the massive jaws of tyrannosaurs
were atypical鈥攎ost other predators were more lightly built.