# Deinonychus antirrhopus

> A wolf-sized dromaeosaurid with a large sickle claw from the Early Cretaceous of Montana. Its 1969 description started the "dinosaur renaissance" and the idea that birds descend from dinosaurs; it was the model for the films' "raptors".

- Classification: Dinosauria (clade) > Saurischia (clade) > Theropoda (clade) > Coelurosauria (clade) > Maniraptora (clade) > Dromaeosauridae (family) > Eudromaeosauria (clade) > Deinonychus (genus) > Deinonychus antirrhopus (species)
- Length: 3.3–3.4 m
- Hip height: 0.8–1 m
- Mass: 60–100 kg
- Age: 121.4–100.5 million years ago (Early Cretaceous)
- Fossils found in: Cloverly Formation (Montana); Wyoming
- Diet: carnivore
- Described: John H. Ostrom, 1969

Canonical page: https://dinodex.club/dinosaurs/deinonychus-antirrhopus
Last updated: 2026-09-27

## Overview

Deinonychus antirrhopus lived in western North America in the Early Cretaceous, about 115 to 108 million years ago. John Ostrom and Grant Meyer found its remains in the Cloverly Formation of Montana in 1964, and Ostrom named it in 1969.

It was a light, agile predator about 3 m long, with a stiffened tail, grasping hands and an enlarged, raised claw on the second toe of each foot. Ostrom argued that such an animal must have been active and warm-blooded, and noticed its many similarities with Archaeopteryx and birds. This work revived the idea that birds are living dinosaurs.

Several Deinonychus have been found with skeletons of the plant-eater Tenontosaurus, which led to the idea of pack hunting. Roach and Brinkman (2007) argued instead for mobbing behaviour like that of modern crocodiles or Komodo dragons. The "Velociraptor" of Jurassic Park was modelled largely on Deinonychus.

## Name meaning

From Greek deinos ("terrible") and onyx ("claw"); antirrhopus, "counterbalancing", for the stiff tail (Ostrom 1969).

## Sources

1. Cohen, K. M., Harper, D. A. T., Gibbard, P. L. & Car, N. (2023). International Chronostratigraphic Chart (v2023/09). International Commission on Stratigraphy. https://stratigraphy.org/ICSchart/ChronostratChart2023-09.pdf
2. Fowler, D. W., Freedman, E. A., Scannella, J. B. & Kambic, R. E. (2011). The predatory ecology of Deinonychus and the origin of flapping in birds. PLoS ONE 6(12): e28964. https://doi.org/10.1371/journal.pone.0028964
3. Maxwell, W. D. & Ostrom, J. H. (1995). Taphonomy and paleobiological implications of Tenontosaurus-Deinonychus associations. Journal of Vertebrate Paleontology 15(4): 707-712. https://doi.org/10.1080/02724634.1995.10011256
4. Ostrom, J. H. (1969). A new theropod dinosaur from the Lower Cretaceous of Montana. Postilla 128: 1-17.
5. Ostrom, J. H. (1969). Osteology of Deinonychus antirrhopus, an unusual theropod from the Lower Cretaceous of Montana. Bulletin of the Peabody Museum of Natural History 30: 1-165.
6. Paul, G. S. (2010). The Princeton Field Guide to Dinosaurs. Princeton University Press.
7. Paul, G. S. (2016). The Princeton Field Guide to Dinosaurs (2nd edition). Princeton University Press.
8. Roach, B. T. & Brinkman, D. L. (2007). A reevaluation of cooperative pack hunting and gregariousness in Deinonychus antirrhopus and other nonavian theropod dinosaurs. Bulletin of the Peabody Museum of Natural History 48(1): 103-138. https://doi.org/10.3374/0079-032X(2007)48[103:AROCPH]2.0.CO;2

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Cite as: "Deinonychus antirrhopus". DinoDex. https://dinodex.club/dinosaurs/deinonychus-antirrhopus (updated 2026-09-27).