Velociraptor is one of the most bird-like dinosaurs ever discovered. It was small and fast, and the sickle-shaped claw on the second toe of each foot made it a formidable predator. A special bone in its wrist allowed it to swivel its wrist sideways in a flapping motion and to fold its arm against its body like a bird. This motion allowed it to snap its arms forward to grab fleeing prey and is an important part of the flight stroke in modern birds.
Credit: Todd Marshall
The vicious Velociraptor of pop culture slashes and disembowels its prey with large, curved claws. The dinosaur gore makes for good cinema, but one research team thinks those claws were made for climbing.
Phillip Manning at the University of Manchester and his colleagues used X-ray scans of fossils from the Late Cretaceous period (spanning from 144 million to 65 million years ago) and drew from knowledge of the material in modern-day owl claws to make a model of the Velociraptor's supposed death sickles.
Velociraptor and other dromaeosaurids were bipedal and lightweight and related to modern birds. A study in 2007 found Velociraptor had feathers, though it could not fly.
Stress tests showed the curved claws "were well-adapted for climbing as they would have been resistant to forces acting in a single (longitudinal) plane, in this case due to gravity," the scientists write in the journal Anatomical Record. "The tip of the claw functioned as the puncturing and gripping element," and the rest of the claw could have transferred the stress to bones.
Previous work by Manning and colleagues, in 2006, used a hydraulic reconstruction of dromaeosaurid limbs to cast doubt on whether the curved claws were effective at disemboweling prey, a long-suspected use for the implements.
The new study found that the claws had a high "failure stress" threshold, "suggesting that Velociraptor would have been able to support its weight on a small contact area while climbing," the researchers write. And it could have perched, much like a modern bird in a tree, they figure.
That doesn't mean Velociraptor wasn't fearsome.
The claws of these extinct creatures could have served to capture prey, too.
"The geometry of dromaeosaur claws would have caused the claw to rotate as it was pushed deeper into prey," the scientists write. A rachet-like ligament would have helped get the claw in deep, they speculate, allowing the dinosaur to use its body weight "to lock the claws passively and allowing the jaws to dispatch the prey."
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