It's not as well-known as Velociraptor, but Deinonychus is the more influential raptor in the paleontology community. Here are 10 facts you may (or may not) have known about Deinonychus. (See 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 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 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). Deinonychus probably used its claws to inflict deep stab wounds on its prey, perhaps withdrawing to a safe distance as its dinner bled to death.
3. The first Deinonychus fossils were discovered in 1931...
Ironically, the famous American paleontologist Barnum Brown discovered fossils of Deinonychus while he was on the prowl for an entirely different dinosaur, 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.
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 accepted as fact today 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 raptor, was smart enough to turn doorknobs.)
7. The jaws of Deinonychus were relatively weak...
Deinonychus had a 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 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, notably the fleet-footed ornithomimids, though a recent analysis shows that it may have walked at a healthy 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, meaning that these two dinosaurs shared the same North American ecosystem. 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 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 implies that this dinosaur must have looked a bit like Big Bird.