10 Fun Facts About Deinonychus

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Wikimedia Commons / Wikimedia Commons

We no longer see dinosaurs as the same oafish, tail-dragging monsters that trudged through King Kong (1933). Over the past 50 years, they’ve undergone an amazing scientific makeover—and if this shift in our perception could be traced back to a single breakthrough, it’d have to be the discovery of an athletic creature named Deinonychus antirrhopus.

1. Deinonychus Helped Revolutionize Dino Paleontology ...

Some odd-looking remains were discovered on a fossil-hunting trip through Montana in 1964. Yale paleontologist John Ostrom quickly deduced that these were the bones of a carnivorous dinosaur that belonged to the theropod suborder. He also realized that this new animal defied almost everything we thought we knew about the “terrible lizards.” This predator clearly wasn’t built for a sluggish, reptilian existence. Instead, its light frame, counterbalancing tail, and huge, hooked claws betrayed an active lifestyle. Perhaps it was even warm-blooded. Five years later, Ostrom released a paper that introduced the world to his game-changing dinosaur, which the scientist called Deinonychus, or “terrible claw.”

2. … And it Revived the Whole Dinosaur/Bird Idea.

Today, virtually all paleontologists recognize that birds are the descendants of dinosaurs. Back in 1970, however, this notion seemed outdated. Naturalists started wondering about a possible link during the mid-to-late 1800s, but the conclusion that birds actually evolved from dinosaurs quickly fell out of favor—until Ostrom came along. In short order, he noted many glaring similarities between Deinonychus’ arms and those belonging to an ancient, feathery critter known as Archaeopteryx, and the long-dormant concept once again took flight.

3. Deinonychus Inspired the Raptors of Jurassic Park.

Didier Descouens, Wikimedia Commons //CC BY-SA 4.0

An unfortunate naming mix-up has kept Deinonychus from getting the celebrity treatment it so richly warrants. In 1988, researcher Gregory S. Paul published a splendid book entitled Predatory Dinosaurs of the World: A Complete Illustrated Guide. At the time, he believed that Deinonychus antirrhopus was really a large, North American species of Velociraptor, an exclusively Asian genus, and his book uses the name Velociraptor antirrhopus instead.

Even then, however, the overwhelming majority of paleontologists strongly disagreed with this assessment. Deinonychus, they argued, was far too different from Velociraptor to be casually lumped together with it. For starters, the Old World dinosaur was only about 6 feet long and had a fairly narrow snout. In contrast, Deinonychus antirrhopus stretched over 11 feet from end to end and sported a much taller snout. Soon enough, Paul heeded their remarks and resumed calling a spade a spade and a Deinonychus a Deinonychus.

But Paul’s work left a big impact on novelist Michael Crichton, who almost certainly used Predatory Dinosaurs of the World as a reference while writing Jurassic Park. So his characters wound up fleeing from an animal that’s obviously modeled after Deinonychus—right down to its size and skull shape—but is called Velociraptor anyway. Stephen Spielberg followed suit, and the rest is pop culture history.

4. Deinonychus and its Kin Probably Weren’t Half as Smart as the Media Would Have You Believe.

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Thanks to Jurassic Park, dromaeosaurs—also known as raptors—have been painted as super-intelligent killers whose IQs were supposedly on par with those of whales and primates. Don’t buy the hype. Though they do appear a bit brainier than your typical dinosaur, it’s impossible to figure out just how smart an extinct animal really was, and even liberal estimates put clever dinosaurs in the same league as ostriches and opossums.

5. Also, There’s no Concrete Evidence that They Hunted in Wolf-Like Packs.

Ostrom himself first suggested this in the '60s after finding the skeletons of three Deinonychus scattered around one Tenontosaurusa much larger herbivore. Case closed, right? Not so fast: Perhaps they were merely squabbling over carrion, Komodo dragon-style. Nowadays, you won’t find any nonmammalian carnivores that form complicated hunting groups. Usually, a disorganized mob works just as well. 

6. Deinonychus Had a Semi-Rigid Tail.

AStrangerintheAlps via Wikimedia Commons // CC BY-SA 3.0

Long, interweaving rods extended from most of its tail vertebrae, which made the appendage abnormally stiff. According to most experts, the dinosaur’s strange tail acted as a counterweight to the rest of its body. Hence, a running Deinonychus could have made sharp turns midstride by suddenly swinging that thing about.  

7. Its Dexterity Left a Lot to Be Desired.   

Listen up, humans: Never, ever take your opposable digits for granted! Deinonychus’ smaller cousin Bambiraptor—and, yes, the lil’ bugger was named after Disney’s wide-eyed deer—had one on each hand, meaning that it could grasp things with relative ease. Deinonychus wasn’t so lucky: Because none of its fingers worked this way, the animal had to pick up an object by squeezing it between its palms.

8. A Probable Deinonychus Egg Has Been Located.   

Certain dinosaurs had stomach ribs called gastralia. These bones (which crocodiles also possess) were situated in the belly, where they helped support vital organs. In 2006, researchers found a few Deinonychus gastralia nestled atop an incomplete fossil egg. Assuming that a Deinonychus actually laid this egg, the position of the ribs implies that one of its parents died while brooding on it like a hen.

9. Deinonychus Most Likely Kept its Arms Folded.  

Emily Willoughby via Wikimedia Commons // CC BY-SA 4.0

By and large, dromaeosaurs have been illustrated with their forelimbs dangling almost limply from their torsos. But in recent years, this portrayal has come under fire. That position would have been ungainly, and although Deinonychus, Bambiraptor, and company couldn’t bend their wrists as far as today’s birds can, they probably spent most of their time with each arm tucked up against the body anyway.

10. We May Have Been Underrating its Bite Force.

Depending on who you ask, Deinonychus either bit weakly or used more chomping power than a hungry hyena. One 2010 analysis of several Tenontosaurus bones laced with Deinonychus tooth marks concluded that in order to leave these punctures, the dino’s jaws had to have been as strong as a present-day alligator’s. But this study had its critics, who argued that Deinonychus’ slender skull didn’t leave room for jaw muscles large enough to cause such damage. Besides, it was plenty frightening without them.