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Deinonychus

The Deinonychus is not as well known as its Asian cousin Velociraptor which it embodied in the films Jurassic Park and Jurassic World but it has much more influence with paleontologists because its many fossils have allowed to learn a lot about the appearance and behavior of raptors dinosaurs.

The name Deinonychus, which means "terrible claw", refers to the huge and unique sickle-shaped curved claw that garnishes each of the hind legs of this dinosaur. It is capable of rotating up to 180 degrees and is a unique feature that Deinonychus shares with its fellow raptors from the Middle and Late Cretaceous periods. The root of the name, "Deino", is the same Greek root as "dino" in dinosaur and is also shared by prehistoric reptiles like Deinosuchus and Deinocheirus.

First discoveries

Skeleton fossil of Deinonychus Antirrhopus
Deinonychus antirrhopus

The earliest fossils of Deinonychus were discovered in 1931 by famous American fossil hunter Barnum Brown, who was visiting Montana in search of bones belonging to another dinosaur, the duck-billed hadrosaur Tenontosaurus. Brown was not really interested in the small specimen of raptor he had excavated and tentatively decided to name it Daptosaurus before relegating it to oblivion.

The Jurassic Park velociraptors are modeled on the Deinonychus

Those familiar with Jurassic's popular franchises are familiar with the original trilogy pack raptors and their beefed-up military counterparts from Jurassic World's newest movies. Very few people are aware, but these virtual dinosaurs are actually modeled on the Deinonychus, a name that producers considered too hard to pronounce to anchor itself in popular culture. And for those who remember the memorable scene where a raptor quickly understands how to turn a doorknob, this is pure fiction and there is absolutely no chance that Deinonychus or any other dinosaur would be capable of such a feat. In comparison, the Troodon, which had the largest brain in proportion to his body and thus the largest IQ of the Mesozoic era, had an intelligence similar to that of chickens. Moreover, contrary to what is presented in Jurassic Park, Deinonychus did not have a green and scaly skin like that of reptiles but rather a dark plumage.

Another detail that Jurassic Park and Jurassic World wrongly depicted is the speed and agility of raptors. In the films these animals are of an almost supersonic speed and very agile; in reality, Deinonychus was much less agile than most other theropod dinosaurs and especially ornithomimids which were very fast and light on their legs. Recent studies have shown that this raptor was able to trot at speeds of about 10 km / h while hunting for prey, which is fast for a human but slow for a dinosaur.

Deinonychus possibly hunted the duck-billed dinosaur Tenontosaurus

Deinonychus vs Tenontosaurus

It is known that Tenontosaurus and Deinonychus shared the same North American territories during the Middle Cretaceous period and that they lived and died in close proximity to each other since Deinonychus fossils are associated with those of the duck-billed dinosaur. One could quickly be led to believe that there was almost certainly a predator-prey relationship between these two dinosaurs. However, an adult-sized Tenontosaurus weighed around 2 tons while Deinonychus weighed at most 200 pounds; to have the slighest chance to feast on the flesh of this duck-billed dinosaur, these raptors had to hunt in cooperative pack of at least 5 individuals if not more.

The difference in size between these animals is all the more important since the strength of the Deinonychus bite was quite weak compared with other Cretaceous theropod dinosaurs such as Tyrannosaurus or Spinosaurus; about the same as that of a modern alligator according to some detailed studies. The weapon of choice of this raptor was rather his hindclaws and his gripping hands which both had to be of little use against a creature as massive as the Tenontosaurus.

Deinonychus used his posterior claws to disembowel its prey

Raptor claw

Paleontologists are still not convinced of how raptors wielded their hind claws, but they were certainly used during hunting and could also help them climb trees when chased by larger theropods. These claws could also have been used to impress females during mating season, although this is still doubtful. Deinonychus probably used its talon to inflict deep cuts on its victims before retiring at a safe distance until they died out of blood.

Deinonychus inspired the theory that birds descended from dinosaurs

Today, paleontologists believe that most theropod dinosaurs, including raptors and tyrannosaurs, had feathers at certain stages of their lives. There is no direct evidence that Deinonychus had plumage, but the existence of such a characteristic in other raptors such as Velociraptor implies that Deinonychus was a bit like a bird, even if only during its young ages. In addition, raptors displayed an evolutionary pattern that is contrary to what is generally encountered in the animal kingdown; they gradually shrunk over time rather than grow. This is one of the most striking signs that these animals were preparing to take off.

Thus, in the late 1960s and early 1970s, American paleontologist John H. Ostrom noticed the similarity between modern birds and Deinonychus and was the first to propose the idea that birds evolved from dinosaurs. This idea seemed completely absurd at the time but is now accepted as a fact in the scientific community.

The first Deinonychus egg was discovered at the turn 21st century

Deinonychus egg

Although the fossilized eggs of other North American theropods such as Troodon abound, those of Deinonychus are relatively rare in comparison. The only specimens known so far were found in 2000 and analyzes suggest that Deinonychus had a gestation similar to that of the Citipati, another feathered dinosaur technically not a raptor but rather an oviraptor theropod.

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