It's not as well-known as Velociraptor (which it played in the first Jurassic Park movie), but Deinonychus is the more influential raptor among paleontologists. Here are 10 facts you may (or may not) have known about this fearsome meat-eater. (See also a gallery of Deinonychus pictures.)
1. Deinonychus is Greek for "terrible claw..."
The name Deinonychus (pronounced die-NON-ih-kuss) references the single, large, curving claws on this dinosaur's hind feet, a diagnostic trait that it shared with its fellow raptors. (The "deino" in Deinonychus, by the way, is the same Greek root as the "dino" in dinosaur, and is also shared by such prehistoric reptiles as Deinosuchus and Deinocheirus.)
2. ...which this dinosaur used to slash at its prey.
Paleontologists are still trying to figure out how raptors used their hind claws, but it's a sure bet that they had some kind of offensive function (in addition to, for example, helping their owners to climb trees in a tight spot). Deinonychus probably used its claws to inflict deep stab wounds on its prey, perhaps withdrawing to a safe distance and waiting for its dinner to bleed to death.
3. The first Deinonychus fossils were discovered in 1931...
Ironically, the famous American paleontologist Barnum Brown discovered the "type fossils" of Deinonychus while he was on the prowl for an entirely different dinosaur, the hadrosaur Tenontosaurus (about which more below). He didn't seem all that interested in the smaller reptile, and provisionally named it "Daptosaurus" before forgetting about it entirely.
4. ...but they weren't fully understood until decades later.
In 1964, John H. Ostrom led a fossil-hunting expedition through Montana and Wyoming, and wound up discovering hundreds of bones later diagnosed as belonging to Deinonychus (a name Ostrom coined to replace Daptosaurus). Today, many of these bones still reside at Ostrom's sponsoring institution, the Yale Peabody Museum of Natural History in New Haven. Connecticut.
5. Deinonychus inspired the theory that birds descended from dinosaurs.
The years John Ostrom spent poring over his Deinonychus bones were not in vain. In the late 1960's and early 1970's, he commented on the similarity of Deinonychus to modern birds--and was the first paleontologist to broach the idea that birds evolved from dinosaurs. What seemed like a wacky theory back then is today accepted as fact by most of the scientific community!
6. Deinonychus was the model for Jurassic Park's Velociraptors.
Remember those scary, man-sized, pack-hunting Velociraptors from the first Jurassic Park movie? Well, those were really modeled on Deinonychus, which the film's producers presumably considered too hard to pronounce. (By the way, there's no chance that Deinonychus, or any other dinosaur, was smart enough to turn doorknobs.)
7. The jaws of Deinonychus were relatively weak...
Deinonychus had a relatively wimpy bite compared to other, larger theropod dinosaurs of the Cretaceous period, such as Tyrannosaurus Rex and Spinosaurus--only about as powerful as that of a modern alligator. This makes sense, since this slender predator's primary weapons were its curved hind claws and its long, grasping hands, not its teeth!
8. ...and it wasn't the fastest dinosaur on the block, either.
Another detail that Jurassic Park got wrong was the blazing speed of Deinonychus (aka Velociraptor). It turns out that this raptor wasn't nearly as agile as other theropod dinosaurs, such as the fleet-footed ornithomimids, though a recent analysis demonstrates that it may have been capable of walking at a brisk clip of six miles per hour (if that sounds slow, try doing it yourself).
9. Tenontosaurus was probably on Deinonychus' lunch menu.
The fossils of Deinonychus are "associated" with those of Tenontosaurus, which means that these two dinosaurs shared the same North American territory. It's tempting to draw the conclusion that Deinonychus preyed on Tenontosaurus, but the problem is that full-grown Tenontosaurus adults weighed about two tons--meaning that Deinonychus would have had to hunt in cooperative packs!
10. Deinonychus was almost certainly covered with feathers.
Today, paleontologists believe that just about every theropod dinosaur (including raptors and tyrannosaurs) sported feathers at some stage in its life cycle. To date, no direct evidence has been found for Deinonychus feathers, but the proven existence of other feathered raptors (such as the real-life Velociraptor) implies that this dinosaur must have looked a bit like Big Bird.