Velociraptor's claw 'trapped prey'

With it, Velociraptor and its relatives would have been able to hold on to large-size prey.

Like an eagle with a rabbit, the victim would have been anchored to the ground while its flesh was torn away and devoured.

The claw may have also contributed to the evolution of flapping wings and - ultimately - flight, scientists believe.

Velociraptor belonged to a group of carnivorous dinosaurs called dromaeosaurids which had much in common with birds.

Unlike its portrayal in Jurassic Park, the dinosaur was only about the size of a large chicken. It is also thought to have had feathers, and possibly small rudimentary "wings" attached to its forelimbs.

All dromaeosaurids shared the distinctive oversized second digit foot claw which was normally held aloft.

Until now most scientists believed the claw was a formidable weapon used for slashing and bringing down prey.

But the new study published in the online journal Public Library of Science ONE uses comparisons with birds of prey to offer a different explanation.

"Modern hawks and eagles possess a similar enlarged claw on their digit twos, something that hadn't been noted before," said US dinosaur expert Dr Denver Fowler, from Montana State University.

"We showed that the enlarged D-2 claws are used as anchors, latching into the prey, preventing their escape. We interpret the sickle claw of dromaeosaurids as having evolved to do the same thing: latching in, and holding on.

"This strategy is only really needed for prey that are about the same size as the predator; large enough that they might struggle and escape from the feet.

"Smaller prey are just squeezed to death, but with large prey all the predator can do is hold on and stop it from escaping, then basically just eat it alive. Dromaeosaurs lack any obvious adaptations for dispatching their victims, so just like hawks and eagles, they probably ate their prey alive too."

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