Dinosaurs with killer claws yield new theory about evolution of flight
Posted by Xeno on December 16, 2011
New research from Montana State University’s Museum of the Rockies has revealed how dinosaurs like Velociraptor and Deinonychus used their famous killer claws, leading to a new hypothesis on the evolution of flight in birds.
“This study is a real game-changer,” said lead author Fowler. “It completely overhauls our perception of these little predatory dinosaurs, changing the way we think about their ecology and evolution.”
The study focuses on dromaeosaurids; a group of small predatory dinosaurs that include the famous Velociraptor and its larger relative, Deinonychus. Dromaeosaurids are closely related to birds, and are most famous for possessing an enlarged sickle-claw on digit two (inside toe) of the foot. Previous researchers suggested that this claw was used to slash at prey, or help climb up their hides, but the new study proposes a different behavior.
“Modern hawks and eagles possess a similar enlarged claw on their digit 2′s, something that hadn’t been noted before we published on it back in 2009,” Fowler said. “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.”
As in modern birds of prey, precise use of the claw is related to relative prey size.
“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,” Fowler said. “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.” …
Note that Jurassic Park got it wrong, velociraptor had feathers.
A new look at some old bones have shown that velociraptor, the dinosaur made famous in the movie Jurassic Park, had feathers. The discovery was made by paleontologists at the American Museum of Natural History and the Field Museum of Natural History.Scientists have known for years that many dinosaurs had feathers. Now the presence of feathers has been documented in velociraptor, one of the most iconic of dinosaurs and a close relative of birds.
… “The more that we learn about these animals the more we find that there is basically no difference between birds and their closely related dinosaur ancestors like velociraptor,” said Mark Norell, a Curator in the Division of Paleontology at the American Museum of Natural History and co-author on the study. “Both have wishbones, brooded their nests, possess hollow bones, and were covered in feathers. If animals like velociraptor were alive today our first impression would be that they were just very unusual looking birds”. ….