An Ultimate Guide to Deinonychus: The Terrible Claw

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Name Meaning“Terrible claw”Height0.87 meters (2.9 feet)
PronunciationDi-non-ih-kusLength3.3 meters (10.8 feet)
EraMesozoicEarly CretaceousWeight60-73 kilograms (132-161 pounds)
ClassificationDinosauria,‭ Saurischia & TheropodaLocationWyoming, Montana, Utah; North America

Deinonychus Pictures

Deinonychus | MR1805 via iStock

The Deinonychus

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Gage Beasley Prehistoric’s Deinonychus Concept

The Deinonychus is now regarded as having an important role in supporting the theory that birds evolved from theropods.

In fact, the naming and description of the species opened the doors toward this possibility. 

John Ostrom’s description of the genus and its only species, Deinonychus antirrhopus, is often regarded as the most significant paleontological discovery of the mid-20th century, as it offered a completely different perspective on the concept of dinosaurs and contributed to the theory that some might have been warm-blooded.

This, in turn, served as a base for future speculation that birds evolved from dinosaurs.

This saurischian theropod lived in North America roughly 115-108 million years ago and is renowned for the sickle-shaped talons on the second toe of each foot, which is why people call it the terrible claw.

Read on to discover more fascinating details about the terrible claw!

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Physical Characteristics

Deinonychus dinosaur roaring by day | Elenarts108 via iStock

The size estimations scientists provide for Deinonychus are based on the few fully mature specimens.

As such, they concluded that this dinosaur was likely 3.3 meters (10.8 feet) long and had a hip height of roughly 0.87 meters (2.9 feet).

It weighed 60-73 kilograms (132-161 pounds). Other specialists argued the creature might have reached a larger mass.

For comparison purposes, we checked the size of other dinosaurs in the Dromaeosauridae family.

We concluded that the Deinonychus was relatively large, as only some family members grew longer than 2.07 meters (6.7 feet) and taller than 1.8 meters (5.9 feet).

The Utahraptor was longer, measuring 6 meters (20 feet) long and 1.2-1.5 meters (3.9-4.9 feet) tall.

Gage Beasley Prehistoric's Deinonychus Size Comparison Chart
Gage Beasley Prehistoric’s Deinonychus Size Comparison Chart

Conversely, the Velociraptor was much smaller, measuring 1.5-2.07 meters (4.9-6.7 feet) long and 0.5 meters (1.6 feet) tall. 

This creature had a relatively large head and a skull length of 41 centimeters (16 inches) and featured powerful jaws equipped with 70 teeth.

They were curved and blade-like.

The snout was relatively narrow, the skull roof was more robust than in other creatures like the Velociraptor, and it lacked depressed nasals.

There were distinctive fenestrae, meaning skull openings, in the skull and the lower jaw that aimed at reducing skull weight.

The forelimbs were large and featured three claws, each borne by three digits, the first being the shortest and the second the longest.

Unlike the forelimbs, the well-developed hind limbs had only one claw each, which grew from the second digit.

Dinosaur Deinonychus in a coastal landscape
The “Terrible Claw” in a coastal landscape | MR1805 via iStock

It measured roughly 10-12.7 centimeters (4-5 inches) long.

However, this single claw was likely enough during predation, as it was sickle-shaped and very effective in subduing prey. 

The Deinonychus was an obligatory biped, and the sickle-like claw had nothing to do with locomotion as it was primarily used to slash or cut.

Members of the Dromaeosauridae are thought to have had feathers.

Although no fossil evidence confirms this is valid for the Deinonychus, scientists believed it was feathered based on general dromaeosaurid characteristics. 

Habitat and Distribution

The Deinonychus was discovered in the Cloverly and Antlers Formations in Montana, Oklahoma, and Wyoming.

Supposedly, it lived in a swamp-like or floodplain habitat consisting of deltas, lagoons, and tropical and sub-tropical forests.

Some scientists argue that the climate was similar to what we now call Louisiana.

Apart from this, very little is known about the ecosystem the Deinonychus was part of.

Behavior and Diet

Deinonychus dinosaur hunting food at a cliff
Deinonychus dinosaur hunting food at a cliff | Elenarts108 via iStock

Physiological characteristics show that the Deinonychus was an active and agile creature.

Its tail likely functioned as a dynamic stabilizer while the host moved around its habitat. 

Scientists concluded it was a bipedal creature with an unusual body posture compared to other theropods.

Physiological characteristics indicate its body posture was similar to modern cassowary, emu, and ostrich.

The Deinonychus was likely a good runner thanks to its strong hind limbs, but it did not reach exceptional running speeds.

Based on the characteristics of its teeth, specialists argue that this “terrible claw” was carnivorous.

Strong evidence indicates it was an active predator that hunted and killed other animals but likely fed on carrion too.

Deinonychus showing its powerful teeth
Deinonychus showing its powerful teeth | Warpaintcobra via iStock

The forelimbs of this prehistoric animal were well-adapted for grasping and holding prey, which further proves it was primarily a predator and not a scavenger.

Additional proof comes from the sickle-like claws on the feet, which served as cutting or slashing aids.

As such, specialists argue that the Deinonychus caught prey, held it in its arms, and used one of the large pedal claws to tear it apart.

This would imply that the dinosaur stood on one leg while tearing its prey apart using the pedal claw.

Here’s where the tail helped, as it was an essential stabilizer element in this predator-prey struggle.

However, this is only one of the many theories regarding the technique the Deinonychus relied on to catch and subdue prey.

It is believed that this agile raptor preyed not only on small animals but also on creatures just as large or even larger than itself, as the pedal claw was well-adapted for deep skin penetration.

A pack of Deinonychus dinosaurs attacks a Tenontosaurus during the Cretaceous Period of North America
A pack of Deinonychus dinosaurs attacks a Tenontosaurus during the Cretaceous Period of North America | CoreyFord via iStock

Paleontological discoveries revealed that Deinonychus individuals might have even hunted in packs, which improved their chances of subduing large prey.

Other studies on Deinonychus life stages suggest that these animals didn’t have complex social behaviors similar to modern pack-hunters.

The only paleontological discoveries that indicate what kind of prey the Deinonychus went after are the ornithopod fossils associated with them.

However, specialists aren’t 100% sure the latter preyed upon the former.

However, since ornithopods were common in the habitat, we cannot rule out the possibility that they served as prey for the famously terrible claw

The bite force of the Deinonychus was estimated at 4,100-8,200 newtons, which is greater than the bite force of any living carnivorous mammal.

Another interesting trait researchers attribute to the Deinonychus is that juveniles were likely capable of engaging in some flying behavior.

Life Cycle

Deinonychus: The agile 'terrible claw' dinosaur, renowned for its intelligence and hunting prowess
Deinonychus: The agile ‘terrible claw’ dinosaur, renowned for its intelligence and hunting prowess | MR1805 via iStock

Like all dinosaurs, Deinonychus reproduced by laying eggs.

While modern birds lay only one egg at a time because they have only one functional oviduct, the terrible claw females laid two eggs at a time thanks to the paired functional oviducts.

Luckily for dinosaur enthusiasts and scientists concerned with the dinosaur reproductive system, paleontologists recovered an egg associated with the “terrible claw.”

The egg measured 7 centimeters (2.8 inches) in diameter. It was discovered in 2000 and has been the topic of many debates about whether it belonged to this genus.

In the end, specialists concluded that random association was unlikely and that it indeed belonged to a Deinonychus.

Deinonychus dinosaur roaring head up by day
Deinonychus dinosaur roaring head up by day | Elenarts108 via iStock

As such, they argued that these creatures probably engaged in brooding or nesting behavior seen in oviraptorids and troodontids.

Some scientists argue that the Deinonychus created open nests to lay their eggs, which were likely blue.

They argued that the discovery of this fossilized egg is a major contribution to outlining the origin of the blue eggs we see in modern birds.

Furthermore, a research paper on the evolution of thermophysiology in saurischian dinosaurs concluded that creatures like the Deinonychus developed as endotherms, similar to modern birds, and relied on body heat transfer for egg incubation.

The babies were likely precocial, meaning they didn’t require parental care after hatching.

This shouldn’t be surprising since many dinosaurs were born precocial. Juveniles and adults likely had different diets and predation techniques. 

Evolution and History

Deinonychus vector illustration
Deinonychus vector illustration | MattGrove via iStock

Supposedly, the first fossils belonging to a genus we now call Deinonychus were recovered in 1964 during an expedition from Yale University’s Peabody Museum, when paleontologists recovered a highly unusual animal destined to become one of the most insightful prehistoric species.

These fossils were discovered in the Cloverly Formation of Wyoming and Montana.

However, as it turned out, these weren’t the first Deinonychus fossils ever discovered.

Scientists later found some remains in the collections of the American Museum.

They had been recovered more than 30 years earlier on Montana’s Crow Indian Reservations.

Upon analyzing these discoveries, John Ostrom (the leader of the 1964 expedition) and Grant E. Meyer concluded the fossils belonged to the same species named Deinonychus antirrhopus.

In 1974, other skeletal elements were discovered that helped Ostrom complete the species description.

Reconstructed skeleton of specimen AMNH 3015, with outdated hand posture
Reconstructed skeleton of specimen AMNH 3015, with outdated hand posture | Daderot via Wikipedia CC0

The discovery of an egg that supposedly belonged to a Deinonychus represents a major contribution to understanding bird evolution.

The same study that focused on the fact that Deinonychus might have been endothermic suggests that this makes them an essential species in the rise of avians.

As such, Deinonychus is now regarded as one of the most important dinosaur species ever discovered, as its fossils set the path toward accepting the theory that birds evolved from dinosaurs.

Interactions with Other Species

A Cretaceous Acrocanthosaurus observing a Tenontosaurus being attacked by a group of Deinonychus.
A Cretaceous Acrocanthosaurus observing a Tenontosaurus being attacked by a group of Deinonychus | Mohamad Haghani via GettyImages

Based on other paleontological discoveries from the Cloverly and Antlers Formations, the Deinonychus was probably contemporary and shared its habitat with the following prehistoric creatures:

  • Ornithischians like Sauropelta, Tatankacephalus, Tenontosaurus, and Zephyrosaurus
  • Mammals like Montanalestes and Astroconodon
  • Turtles like Naomichelys

Since it was a fierce predator, the Deinonychus probably hunted many of the abovementioned creatures.

Still, the most significant evidence connects it to the Tenontosaurus, a 7-meter (23 feet) ornithopod that weighed ten times as much as the Deinonychus.

Can you imagine how strong the terrible claw was if it could subdue such large prey?

Paleontological discoveries revealed that teeth and skeletons belonging to Deinonychus were often associated with Tenontosaurus remains.

Of the 50 locations where Tenontosaurus fossils were found, 14 contained Deinonychus remains as well. As such, scientists suggest that the latter was a major predator of the former.

Deinonychus skeletal mount on display at the Field Museum of Natural History.
Deinonychus skeletal mount on display at the Field Museum of Natural History | Jonathan Chen via Wikipedia CC BY-SA 4.0

Whether Deinonychus individuals hunted in packs remains a mystery, although this theory could shed light on how it could subdue such large prey.

Other theories imply that it probably preferred juvenile Tenontosaurus individuals.

The Acrocanthosaurus was likely an apex predator in their habitat, although it rarely crossed paths with the Deinonychus.

First, the terrible claw probably wasn’t a preferred meal for the large carnivore, as it usually fed on sauropods and large ornithopods.

Moreover, they likely weren’t food competitors, as they preyed upon different animals.

Cultural Significance

Deinonychus skull
Deinonychus skull | bobainsworth via iStock

As we’ve already established, the discovery of Deinonychus fossils represents one of the most significant paleontological events that led to a myriad of speculations and theories, some of which have been confirmed, while others await further proof-carrying discoveries.

Who would’ve thought that, besides being of major interest to scholars, the Deinonychus would be a favorite among dinosaur enthusiasts?

If you’ve read this article, you know what we’re discussing! The Lost World, Jurassic Park, and Carnosaur are only some books and movie adaptations featuring this fearsome creature!

Did you know that Michael Crichton, the author of the novel The Lost World, met with John Ostrom, who first described the Deinonychus, to learn more about this carnivorous biped?

Although he used the term “Velociraptor” instead of “Deinonychus,” every detail used to describe it was related to the terrible claw.

As per the author, he opted for Velociraptor because it sounded more dramatic.


What a journey it was!

We’ve discovered so many jaw-dropping details about the renowned Deinonychus that we’ll undoubtedly need some time to process them!

Here’s a short recap of our discussion to ensure you don’t forget the essential things.

Deinonychus was a bipedal carnivore that lived in North America during the Early Cretaceous, approximately 115-108 million years ago.

Although relatively small, it was an expert at hunting and killing prey that was usually much larger than itself.

Besides this, the Deinonychus is known for having a sickle-like claw on each foot, which helped it subdue prey.


Are Deinonychus Velociraptors?

Deinonychus and Velociraptor are different creatures.

They form different genera, but both are eudromaeosaur theropods.

Is Deinonychus a Utahraptor?

Deinonychus and Utahraptor are different creatures.

They form different genera, but both are eudromaeosaur theropods.

Is Blue from Jurassic World a Deinonychus?

Blue from Jurassic World is a Velociraptor.


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