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Deinonychus

life science Maturity 5-7 Next article →

Deinonychus is a genus of dromaeosaurid theropod dinosaur. This group of dinosaurs includes many famous meat-eaters. The only known species is Deinonychus antirrhopus. This animal lived during the Early and Late Cretaceous Period. This was about 115 to 93.9 million years ago.

Dromaeosaurs
Dromaeosaurs

Scientists find these fossils in several U.S. states. These include Montana, Utah, Wyoming, and Oklahoma. Some teeth may even belong to this genus in Maryland. Understanding Deinonychus is important because it changed how we see all dinosaurs.

Deinonychus ewilloughby
Deinonychus ewilloughby

The body of Deinonychus was built for active hunting. It had a sleek, horizontal posture. This means it held its body out rather than upright. The dinosaur had a large, sickle-shaped claw on its second toe. This is called a raptorial claw. In life, a horny sheath covered the bone of this claw. This sheath made the talon even longer.

Deinonychus patte arrière gauche
Deinonychus patte arrière gauche

The tail was also a vital part of its movement. The tail vertebrae had ossified tendons, which are hardened tissues. These tendons made the tail stiff. This stiffness allowed the tail to act as a counterbalance. This helped the animal stay steady while moving quickly.

Deinonychus (Raptor Prey Restraint)
Deinonychus (Raptor Prey Restraint)

We can learn a lot about its diet from fossil evidence. In the Cloverly and Antlers formations, fossils of Deinonychus are found near Tenontosaurus. Tenontosaurus was an ornithopod dinosaur. Teeth found near these fossils suggest that Deinonychus hunted or scavenged them. This has led scientists to debate how these dinosaurs lived. Some think they were solitary animals. Others suggest they were gregarious, meaning they lived in groups. However, they did not live in mammal-like packs.

Deinonychus antirrhopus - AMNH - DSC06297
Deinonychus antirrhopus - AMNH - DSC06297

The history of discovering Deinonychus is very interesting. In 1931, Barnum Brown found the first remains in Montana. He was actually looking for Tenontosaurus at the time. He found a small carnivore but did not finish describing it. He called it "Daptosaurus agilis" in his notes. Decades later, John Ostrom reviewed this material. He realized the teeth and skeletons belonged to different animals. In 1964, Ostrom led a new expedition near Bridger. His team found over 1,000 bones from at least three individuals.

Deinonychus antirrhopus hand
Deinonychus antirrhopus hand

Ostrom officially named the species in 1969.

Deinonychus skull ROM
Deinonychus skull ROM

The size and shape of Deinonychus were quite impressive. One researcher, Paul, estimated its skull length and hip height. Another scientist, Campione, suggested a higher mass estimate. This was based on the size of the femur and humerus. The skull had about seventy curved, blade-like teeth. It also had fenestrae, which are openings in the skull. These openings helped reduce the total weight of the head. The antorbital fenestra, a hole between the eye and nostril, was very large. This helped make the skull lighter for an active predator.

Deinonychus Steveoc
Deinonychus Steveoc

Recent discoveries have added even more to our knowledge. In 2000, researchers looked at old, unprepared fossil blocks. They found fossilized eggshells in the rock surrounding a specimen. This might be the first identified egg from a dromaeosaurid. The eggshell was touching a gastralium, which is an abdominal rib. This suggests that Deinonychus might have brooded its eggs. Brooding means using body heat to keep eggs warm. This points toward endothermy, or being warm-blooded, like modern birds.

Archaeo-deinony hands
Archaeo-deinony hands

Deinonychus is a key link in understanding the history of life. Ostrom noticed the forelimbs looked very similar to those of birds. This observation helped revive the idea that birds descended from dinosaurs. Today, most scientists accept this connection. Because it was so similar to birds, many believe it had feathers. While we have no skin impressions for Deinonychus, other related dinosaurs like Velociraptor do have them. This makes the connection to modern birds even stronger.

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🖼️ Images & Media (32)
File:Deinonychus patte arrière gauche.jpg
Deinonychus patte arrière gauche.jpg
File:Harvard Deinonychus.jpg
Harvard Deinonychus.jpg
File:Deinonychus antirrhopus - AMNH - DSC06297.JPG
Deinonychus antirrhopus - AMNH - DSC06297.JPG
File:Archaeo-deinony hands.svg
Archaeo-deinony hands.svg
File:Dromaeosaurs.png
Dromaeosaurs.png
File:Austroraptor Restoration.png
Austroraptor Restoration.png
File:Changyuraptor.png
Changyuraptor.png
File:Bambiraptor reconstruction.jpg
Bambiraptor reconstruction.jpg
File:Adasaurus Restoration.jpg
Adasaurus Restoration.jpg
File:Tsaagan.png
Tsaagan.png
File:Saurornitholestes langstoni skeletal.png
Saurornitholestes langstoni skeletal.png
File:Fred Wierum Velociraptor.png
Fred Wierum Velociraptor.png

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