# Deinocheirus mirificus

> A giant, humpbacked ornithomimosaur from the Late Cretaceous of Mongolia, known for decades only from a pair of 2.4 m arms. New skeletons in 2014 revealed a duck-like snout, a sail on its back and a stomach full of stones and fish.

- Classification: Dinosauria (clade) > Saurischia (clade) > Theropoda (clade) > Coelurosauria (clade) > Ornithomimosauria (clade) > Deinocheiridae (family) > Deinocheirus (genus) > Deinocheirus mirificus (species)
- Length: 11 m
- Hip height: 2.9–3.5 m
- Mass: 6.4 t
- Age: 72.1–66 million years ago (Late Cretaceous)
- Fossils found in: Nemegt Formation (Ömnögovi Province); Mongolia
- Diet: omnivore
- Described: Halszka Osmólska & Ewa Roniewicz, 1970

Canonical page: https://dinodex.club/dinosaurs/deinocheirus-mirificus
Last updated: 2026-09-27

## Overview

Deinocheirus mirificus lived in the Nemegt Formation of Mongolia at the end of the Cretaceous. The 1965 Polish-Mongolian expedition found its holotype at Altan Uul III: mostly a pair of giant forelimbs, 2.4 m long, with shoulder girdles. Halszka Osmólska and Ewa Roniewicz named it in 1970, and for almost fifty years it remained a mystery.

Two new skeletons, found in 2006 and 2009, were described by Lee and colleagues in 2014. Deinocheirus turned out to be the largest ornithomimosaur: a heavily built, slow animal with a long, toothless snout, a deep jaw, very tall spines along the back, short hind legs and broad, blunt toe claws.

More than a thousand gastroliths and fish remains in its body cavity suggest it was a giant omnivore of wet environments. Parts of one skeleton had been poached and sold abroad before being returned to Mongolia in 2014.

## Name meaning

"Terrible hand", from Greek deinos ("terrible") and cheir ("hand"); mirificus, Latin for "unusual, peculiar" (Osmólska & Roniewicz 1970).

## Sources

1. (2026). Paleobiology Database: Deinocheirus occurrences. The Paleobiology Database (paleobiodb.org), data service 1.2, accessed 2026-09-23. https://paleobiodb.org/data1.2/occs/list.txt?base_name=Deinocheirus&show=coords,paleoloc,strat,loc,ref&pgm=gplates
2. (2026). Wikipedia: Deinocheirus. Wikipedia (English), accessed 2026-09-23. https://en.wikipedia.org/wiki/Deinocheirus
3. 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
4. Lee, Y.-N., Barsbold, R., Currie, P. J., Kobayashi, Y., Lee, H.-J., Godefroit, P., Escuillié, F. & Chinzorig, T. (2014). Resolving the long-standing enigmas of a giant ornithomimosaur Deinocheirus mirificus. Nature 515: 257-260. https://doi.org/10.1038/nature13874
5. Osmólska, H. & Roniewicz, E. (1970). Deinocheiridae, a new family of theropod dinosaurs. Palaeontologia Polonica 21: 5-19.
6. Paul, G. S. (2016). The Princeton Field Guide to Dinosaurs (2nd edition). Princeton University Press.

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Cite as: "Deinocheirus mirificus". DinoDex. https://dinodex.club/dinosaurs/deinocheirus-mirificus (updated 2026-09-27).