Category: Dinosaur

Deinonychus (Dye-NON-ick-us) lived during the Early Cretaceous Period, from 115 to 108 million years ago. It lived in what is now North America. It was a fast, effective predator with an enlarged, curved claw on the second toe of each foot. It was closely related to Velociraptor.



Genera and Species

Classification: Saurischia. Theropoda. Dromaeosauridae.

Genus: Deinonychus (“Terrible Claw”)

Species: D. antirrhopus


Deinonychus had a long tail, large hands, powerful legs, and a mouthful of blade-like teeth. The second toe on each foot featured a sharp, sickle-shaped claw, much like its close relative Velociraptor. Like Velociraptor and other dromaeosaurids, Deinonychus is believed to have been covered with bird-like feathers.


LENGTH: 3.4 meters (11 feet, 2 inches)

WEIGHT: Estimated 73-100 kg (161-220 lbs)


Deinonychus is thought to have been a strong predator, hunting large animals in packs. Some scientists think it may have used its large, sickle-shaped claws to pin prey down and grasp it tightly, preventing escape. Other believe it used its claw to slash at its prey to wound it and make it easier to subdue.

History of Discovery

The first fossils of Deinonychus were discovered in 1931 by a team led by Barnum Brown, who at the time was more concerned with digging up the remains of another dinosaur, Tenontosaurus.

About 30 years later, paleontologist John Ostrom found much more Deinonychus material, allowing him to describe the dinosaur in more detail. His description shook the world of paleontology and changed a lot about how many people viewed dinosaurs. He believed that Deinonychus was a quick and agile predator, not the lumbering, slow-moving dinosaurs that was the common public perception at the time.

This led to even more ideas, such as the suggestion that dinosaurs were warm-blooded, and may have more in common with modern day birds than reptiles. This “Dinosaur Renaissance” would reshape how many people pictured dinosaurs, and we now know not only that dinosaurs were warm-blooded, but that many had feathers and very likely evolved into birds.


Deinonychus lived in what is now Montana. Its environment is believed to have been a semi-arid floodplain with prairies, woodlands and forests, or a swamp-like habitat like modern day Louisiana.

Deinonychus lived alongside dinosaurs including the ankylosaur Sauropelta, the theropod Acrocanthosaurus, the giant sauropod Sauroposeidon, and the ornithopod Tenontosaurus.



2. Paul, G. (2016). The Princeton Field Guide to Dinosaurs, 2nd Edition. Princeton, New Jersey: University Press Princeton.