Jurassic Park may have led you to believe that Velociraptors were six-foot tall ferocious beasts, but in reality the feared reptilian antagonists were feathered dinosaurs no larger than a turkey. There were bigger raptors out there, however, once again confirmed by a new study: the recently-discovered Dakotaraptor is 5 meters (16 feet 6 inches) long, and was armed with a 19 centimeter-long (7.5 inch) killing claw. This novel raptor was described in a paper published by the University of Kansas Paleontological Institute.
This meat-eating monster would have no doubt been an apex predator – a predator at the top of the local food chain – terrorizing herbivorous dinosaurs in the area as it chased them down. It’s likely that it hunted its prey much like the other raptors: storming towards it and pouncing, using its killing claw to pierce the victim’s skin and pin it to the ground. It would have co-existed with the Tyrannosaurs, and would have been able to compete for prey with any juveniles.
Image credit: A look at the frightening raptorial foot claws of the new giant raptor. DePalma et al., 2015.
Perhaps most strikingly, the attachment points for feathers were found on its ulna, the longer, thinner bone present in the forearm. These “quill knobs” appeared to be strong and robust, indicating that not only did this raptor have feathers, but it had a pronounced wingspan when its arms were outstretched. Although the dimensions and mass of the Dakotaraptor meant that it was unable to fly, it may have used these wings to stabilize itself when leaping towards its prey, and perhaps allowing it to briefly glide in order to extend its deadly grasp.
Modern-day birds are the living descendants of a large group of feathered dinosaurs called the Coelurosauria, which includes Deinonychus, Tyrannosaurus, and the Velociraptor. Birds use feathers for multiple reasons, but flight is their most prominent. Their ancient cousins evolved feathers perhaps initially to help regulate their internal body temperature, but it has been suggested that some of these dinosaurs may have been able to glide using their plumage.
This new giant raptor – and Coelurosauria family member – has thrown a spanner into the works: quill knobs are thought to be specific adaptations for flight, but as aforementioned, this raptor couldn’t fly. This indicates that it perhaps evolved from a creature that once had the ability to fly but lost it over time as it continued to evolve.
This incredible find was excavated from the Hell Creek Formation, a famous multiple state-spanning site for finding well-preserved dinosaurs that lived in the Upper Cretaceous period, the last chapter of geological time before the Chicxulub asteroid impact drove the non-avian dinosaurs to extinction. A duck-billed Hadrosaur called “Dakota” was uncovered from the site’s North Dakota locality a few years back; this “mummified” dinosaur was so pristinely preserved that muscle mass and soft tissue were still present 67 million years after it was buried.
The new Dakotaraptor (Dakotaraptor steini) was carefully removed from the site’s location in South Dakota after it was discovered by paleontologists in 2005 – the bones of both its arms, some leg bones, ten of the vertebrae in its tail, and its intimidating killing (or sickle) claw were found.