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Scientific Classification
Kingdom: Animalia
Phylum: Chordata
SuperOrder: Dinosauria
Order: Theropoda
Family: Dromaeosauridae
Genus: Deinonychus
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The Deinonychus was a dinosaur that was present on the earth in the early Cretaceous Period. It belonged to the coelurosaurian group of dinosaurs, which is the category that holds those dinosaurs which were more closely related to birds than carnosaurs. This description is enough to tell that the Deinonychus was carnivore and its body was probably covered by feathers.
The fossils of this dinosaur date back to about 118 to 108 million years ago. This places the Deinonychus in the Aptian and Albanian ages of the Cretaceous. It was a medium sized theropod, with an adult length of 11 meters. Its weight is estimated to be close to 70 to 78 kilos, which indicates that this dinosaur was not very stout.
It is interesting to note that the Velociraptor portrayed in the movie Jurassic Park suspiciously looked like the Deinonychus. Both these dinosaurs belong to the same family, with the Deinonychus preceding the Velociraptor by 30 odd million years. The skull of the ‘movie Velociraptor’ resembled that of the Deinonychus more closely than its real life counterpart. Furthermore, the dinosaur in the movie was of a similar size as the Deinonychus (the actual velociraptor being 30 percent smaller).
Some sources say that the writers of Jurassic Park had the Deinonychus in mind, but chose to call their dinosaur a Velociraptor as it was easier to pronounce!

The word Deinonychus is a combination of two Greek words. The term ‘deinos’ is Greek for ‘formidable’, and the suffix is derived from this term. The words ‘onyx zoou’ roughly translates to ‘claw’ in English; the suffix takes inspiration from these Greek words. Thus, the name Deinonychus indicates ‘formidable claw’. This name refers to the strong clawed digit of the hind leg of the dinosaur.
The specific name D. antirrhopus is derived from the Greek word ‘antirropos’ which means ‘counterbalancing’. This probably is a nod to the unique manus of the reptile that was used balance its body while walking and running with the large talon.
The generic and species name of this dinosaur was coined by John Ostrum.

Discovery of fossils

  • The fossils of the Deinonychus were originally discovered by scientist Barnum Brown in the Cloverly Formation of Montana in 1931. Since he was studying the bones of the Tenontosaurus at that time, he classified the bones of the Deinonychus under a new genus Daptosaurus. He did not describe them at that time.
  • A few years later, Brown found another new carnivorous dinosaur skeleton that had disproportionately large teeth. He named this dinosaur Megadontosaurus. He did not describe these fossils either.
  • Three decades later, paleontologist John Ostrom led an expedition in Bridger that led to the discovery of many new theropod bones. Due to the fact that it was difficult curate these bones according to individual dinosaurs, only the partial potions of both the feet of one particular specimen was used to define the genus Deinonychus.

Since it was described based only upon foot bones, the name of the dinosaur seems to make even more sense!

  • By 1969, Ostrom had examined the bones found by Brown and found that they belonged to the Deinonychus. He even observed that the teeth found with Brown’s second theropod find could be linked to the Deinonychus. He renamed the rest of the bones as genus Microvenator.
  • A few more specimen have been recovered from the Antlers Formation of Oklahoma and the Potomac Formation of Maryland.

The dinosaur renaissance
John Ostrom made a remarkable observation while studying the bones of the Deinonychus in the 1960s. He found the forelimb of this dinosaur to be surprisingly similar to that of the Archaeopteryx. Due to this, he postulated that dinosaurs were not sluggish cold blooded beings, but were active and warm blooded. He even theorized that birds evolved from dinosaurs.
This viewpoint revolutionized the way paleontologist perceived dinosaurs. Today, over half a century later, most scientists agree with Ostrom.

The Deinonychus is classified under suborder Theropoda, family Dromaeosauridae and clade Eudromaeosauria. It was related to the Velociraptor and could have shared a common ancestor with it.
Dromaeosaurids are the bird-like theropods. They are often referred to as ‘raptors’ a moniker made popular by the movie Jurassic Park.

Physical features

  • Size:

The Deinonychus was an intermediately large dinosaur. Its adult weight was about 150 to 200 pounds and its length was about 3.5 meters. It likely stood a little over 3 feet tall.

  • Jaws:

The maxillae and mandible of the Deinonychus had curved and sharp teeth. These could inflict considerable damage to its prey. Scientists have found out that the bite force of its jaws was quite high for its size. But it likely did not use its teeth to tear or bite its prey, but rather used the bite force to subdue its victims.

  • Feathers:

The remains of this dinosaur have never been associated with feather fossils. But considering the fact that most other dromaeosaurids had feathers, the Deinonychus had them too.

  • Limbs:

The forelimbs of the Deinonychus had three digits and its hind limbs had four digits each. The eponymous talon was present on the second digit of the hind leg. The exact function of this appendage is debatable.

Habits and habitat

  • The Deinonychus was a bipedal dinosaur. Some paleontologist believe that it would keep its sharp talon suspended in the air while walking, and used only its third and fourth digit for support. Dromaeosaurids are believed to the swift animals, but the femur of the dinosaur was almost similar in size with its tibia, indicating that it was not as swift as modern day flightless birds.
  • The most recently held belief about the talon of this dinosaur is that it was used for climbing and not for ripping the bellies of its opponents.
  • In the year 2000, a Deinonychus fossil was found almost sitting atop an egg. This egg was established as a theropod and was linked to the Deinonychus itself. It is likely that the dinosaur was brooding the egg or that it was located within the oviduct of the female.
  • The habitat of this dinosaur consisted of swamps and marshes.

Related species
The Deinonychus was related to the Atrociraptor and the Achillobater. It probably shared its environment with the Sauropelta, Acrocanthosaurus, Sauroposeidon, etc. It probably hunted the Tenontosaurus.

The final notes
The Deinonychus, while not as dangerous as the tyrannosaurids, was a feared predator nonetheless. Its discovery helped scientists understand the relationship between birds and dinosaurs.