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Dino Index



2.5 -3.5 m

1.6 meters

70 Kilogra



Dai – Nah – Ni – Kus


How Big Was Deinonychus?

Deinonychus was probably as tall as a man when standing, though with the tail, the whole length was 2.5 to 3.5 meters long. With a mass of 50 to 70 kg , this was not one of the big carnosaurs, but he was a scary foe all the same (you wouldn’t want to mee him in a dark alley…).

Where Did Deinonychus Live?

Deinonychus fossils have been found in Montana, Wyoming, and Oklahoma. Teeth that may be Deinonychus teeth have been found as far away as Maryland, but thay have not been identified for certain yet. The type of environment Deinonychus was found in were tropical or sub tropical forests and lagoons, rather similar to Louisiana today (with appropriate mid-Cretaceous plants).

What is Special About Deinonychus?


Deinonychus started the Dinosaur Renaissance with the discovery of new fossils by Ostrom (Deinonychus was first discovered in 1931 by Barnum Brown) who suggsted that Deinonychus was warm blooded. Until then everyone thought dinosaurs were big, slow and cold-blooded. Ostrom suggested that they were warm-blooded partly because he found fossils that strongly looked like Deinonychus was sitting on top of eggs to keep them warm, like a bird does. He also got he idea that dinosaurs were ancestors of birds.


Unlike the other carnosaurs, Deinonychus had rather long powerful arms, and these arms had sharp claws that could be used to hold things. While we think they could not hold both arms out at the same time, one arm or the other could be held out to grab things, and they could pull them in towards their body, clutching it at their chest if they wanted to. Perhaps these arms were used when hunting to help it hold on to its prey.

Sickle Claw

As it was attacking the prey, Deinonychus probably used a single long sickle like claw on its back legs to do much of the dirty work killing the prey. This sickle like claw was really long. It was so long and curved infact, that the whole toe had to be raised when it walked. It had a joint on it that bent backwards so it could raise this toe while it walked. It is not prefectly clear whether Deinonychus used the claw for slashing (to maybe cut open the stomach of its prey), or stabbing. Either way, it was a scary weapon, and probably quite effective.

Hunted Packs or Not

Some dinosaur experts think that Deinonychus used to hunt in packs to kill its prey. The reason for this is that the Deinonychus fossils have been found together with Tenontosaurus fossils and there are marks on the Tenontosaurus that could easily be from Deinonychus teeth. If Deinonychus hunted Tenontosaurus, they could not do it alone since Tenontosaurus was just too big. There are tracks that show a dinosaur that could be made Deinonychus.

These tracks make it look like Deinonychus was walking together at about the same speed, so we think they did not attck each other but perhaps worked together. On the other hand, there are no know examples of lizards hunting in packs, or working together like this. Komodo dragons don’t do it, and neither do crocodiles. This does not mean that Deinonychus did not hunt in packs, but simply that we cannot be certain either way.


Deinonychus had a great brain mass to body mass ratio. This does not mean it was smart beyond a doubt, but if it can be an indicator, it would mean that Deinonychus was one of the smarter for sure. (remember that humans are thought to be smart, but they don’t have the most impressive ratio of all animals either)


Most pictures of Deinonychus show a rather standard looking (albeit scary) lizard like dinosaur, but Deinonychus might actually have been much more like a bird. Deinonychus belongs to the group called dromaeosaurs, and all dromaeosaur skin impressions show feathers. In fact, there is clear evidence that Velociraptor and Microraptor both had feathers. We don’t know if Deinonychus had feather for sure, but it looks safe to think they probably did.

What Other Dinosaurs Lived at the Same Time?

They lived together with Tenontosaurus which was a big sauropod. Carnotaurus also lived at the same time, as did another carnosaur, CarcharodontosaurusIguanadon also lived around the same time. However, if we think about the ecosystem that Deinonychus lived in then we might picture it living alongside dinosaurs like Acrocanthosaurus, and Sauroposeidon. the crocodilian Goniopholis, and the gar Lepisosteus also probably lived nearby.

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