The great white shark may have awesome jaws but they are nothing compared with those of megalodon, its gigantic, whale-eating ancestor. 

A new study of the extinct
creature's skull shows it had an almighty bite, making the prehistoric fish one of the most fearsome predators of all time. 

All the more
remarkable, scientists say, because the crushing force came from jaws made of cartilage, not bone

The researchers report their
skull work in the Journal of Zoology

The
megalodon super-shark swam in the oceans more than a million-and-a-half years ago. 

It grew up to 16m (52ft) in
length and weighed in at 100 tonnes - 30 times heavier than the largest great white - and must have been one of the most formidable carnivores to have existed. 

"
Pound for pound, your common house cat can bite down harder, " explained Dr Stephen Wroe of the University of New South Wales, Australia. "But the sheer size of the animal means that in absolute terms, it tops the scales." 

See a comparison of modern and ancient sharks


Measuring up
 

Dr Wroe's team used a technique known as
finite element analysis to compare the skulls of the great white with that of the prehistoric megalodon

The
approach is a common one in advanced design and manufacturing, and allows engineers to test the performance of load-bearing materials, such as the metal in the body and wings of an aeroplane

CT (X-ray) scans were taken of
megalodon remains to construct a high-resolution digital model. 

A model of a modern 2.4m-long male great white shark (
Carcharodon carcharias) was developed for comparison.

Megalodon
's muscles were based on those of the great white, and the simulations were then loaded with forces to see how the two skulls, jaws, teeth and muscles would have coped with the mechanical stresses and strains experienced during predation

By looking at the
distribution of stress and strain on the sharks' jaws, researchers found that the largest great whites have a bite force of up to 1.8 tonnes, three times the biting force of an African lion and 20 times harder than a human bites. 

Megalodon
, though, is more impressive. It is predicted to bite down with a force of between 10.8 to 18.2 tonnes. 

The team said biting with such force was quite a
feat given that the jaws of these ancient creatures were made of flexible cartilage

In
contrast to most other fish, sharks' skeletons are made up entirely of cartilage. Scientists think that cartilage, being a much lighter material than bone, allows sharks to swim without the aid of a swim bladder.

ieltspass 發表在 痞客邦 PIXNET 留言(0) 人氣()