DinoDex
Humped, long-armed feathered dinosaur with a duck-like snout walking in side view
Life restoration of the giant ornithomimosaur Deinocheirus mirificus from the Nemegt Formation of Mongolia.Image credit: PaleoNeolitic, CC BY 4.0, via Wikimedia CommonsCC BY 4.0Source (opens in a new tab)

Deinocheirus mirificus

Pronounced DYE-noh-KY-rus mih-RIF-ih-kus

Ornithomimosauria · Deinocheiridae

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.

  • Bipedal
  • Giant
  • Giant claws
  • Sail backed
  • Unusual anatomy
Compare
Period
Cretaceous· Maastrichtian
Diet
Omnivore
Length
11 m
Mass
6,360 kg
Location
Ömnögovi Province, Mongolia, Asia

Quick answers

How big was Deinocheirus mirificus?
Deinocheirus mirificus was about 11 m long. It stood about 2.9–3.5 m tall at the hips. It weighed about 6.4 t. (Wikipedia: Deinocheirus 2026; Lee et al. 2014)
When did Deinocheirus mirificus live?
Deinocheirus mirificus lived during the Late Cretaceous, about 72.1–66 million years ago. (Paleobiology Database: Deinocheirus occurrences 2026; Cohen et al. 2023)
Where have Deinocheirus mirificus fossils been found?
Fossils of Deinocheirus mirificus have been found in Nemegt Formation (Ömnögovi Province) and Mongolia. (Osmólska & Roniewicz 1970; Lee et al. 2014)
What did Deinocheirus mirificus eat?
Deinocheirus mirificus was a omnivore. (Osmólska & Roniewicz 1970; Lee et al. 2014)
Who named Deinocheirus mirificus, and when?
Deinocheirus mirificus was described by Halszka Osmólska & Ewa Roniewicz in 1970. (Osmólska & Roniewicz 1970; Lee et al. 2014)

On this page

DYE-noh-KY-rus mih-RIF-ih-kus

Period
Cretaceous72.1–66 Ma
Diet
Omnivore
Length
11 m
Mass
6.4 t
Location
Mongolia, Asia
Classification
Ornithomimosauria · Deinocheiridae
Described
1970, Halszka Osmólska & Ewa Roniewicz

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).

Biology & evidence

What scientists think about how this animal lived, and how strong the evidence for each idea is.

Locomotion

  • Deinocheirus was a slow, heavy animal rather than a runner.

    Evidence level: Moderate evidence

    Unlike its fast relatives, it had short hind limbs and a heavily built body.

    Evidence for / against · 1
    Evidence for

    • Specimen · New Deinocheirus skeletons

      Two skeletons showing an elongate snout, deep jaw, tall neural spines, a pygostyle, a U-shaped furcula, an expanded pelvis, short hind limbs and broad-tipped toe claws.

      Specimen: MPC-D 100/127, MPC-D 100/128

Feeding

  • Deinocheirus was a giant omnivore that also ate fish.

    Evidence level: Moderate evidence

    Its skull suggests plant-eating, while gut stones and fish remains show a mixed diet in wet environments.

    Evidence for / against · 2
    Evidence for

    • Specimen · Deinocheirus gastroliths and stomach contents

      More than a thousand gastroliths and fish remains in the body cavity.

      Specimen: MPC-D 100/127

    • Specimen · New Deinocheirus skeletons

      Two skeletons showing an elongate snout, deep jaw, tall neural spines, a pygostyle, a U-shaped furcula, an expanded pelvis, short hind limbs and broad-tipped toe claws.

      Specimen: MPC-D 100/127, MPC-D 100/128

Other

  • Deinocheirus was the largest ornithomimosaur.

    Evidence level: Strong evidence

    Phylogenetic analysis of the new skeletons places it in Ornithomimosauria, the "ostrich dinosaurs", of which it is by far the biggest.

    Evidence for / against · 1
    Evidence for

    • Specimen · New Deinocheirus skeletons

      Two skeletons showing an elongate snout, deep jaw, tall neural spines, a pygostyle, a U-shaped furcula, an expanded pelvis, short hind limbs and broad-tipped toe claws.

      Specimen: MPC-D 100/127, MPC-D 100/128

Size

Length
11 m

(36.1 ft)

Height
3.2 mpublished range 2.9–3.5 m

(10.5 ft)

Based on MPC-D 100/127 (femur c. 1.32 m)

Mass
6,360 kg
Deinocheirus mirificus was about 11 m (36.1 ft) long, roughly 6.1 times the height of a 1.8 m adult human.

Timeline

Lived from about 72.1 to 66 million years ago (Ma), within the Mesozoic era (252–66 Ma).

Periods: Maastrichtian (72.1–66 Ma), Late Cretaceous (100.5–66 Ma)

Maastrichtian bounds of the type collection in PBDB.

Location

Formations

Map data: Natural Earth (public domain). Modern positions, not where the continents were then.

These are the places where fossils have been found, not the full area where the animal lived.

Ecosystem

Nemegt Basin ecology: a Tarbosaurus feeding on a Deinocheirus carcass, with Saurolophus and other Nemegt dinosaurs (Chiarenza & Bonadonna 2024).Image credit: Alfio Alessandro Chiarenza, Davide Bonadonna, CC BY 4.0, via Wikimedia CommonsCC BY 4.0Source (opens in a new tab)

Lived in: Nemegt

72–68 million years ago · river system, floodplain, forest, swamp / wetland

Wetter than the Djadokhta dunes before it: braided rivers, channels and floodplain forests in the Late Cretaceous Gobi, supporting large herbivores and the tyrannosaurid Tarbosaurus.

Same ecosystem

Therizinosaurus cheloniformis

Cretaceous· MaastrichtianHerbivore

Same ecosystem

Tarbosaurus bataar

Cretaceous· MaastrichtianCarnivore

Same ecosystem

Gallimimus bullatus

Cretaceous· MaastrichtianOmnivore

Classification

  1. cladeDinosauria
  2. cladeSaurischia
  3. cladeTheropoda
  4. cladeCoelurosauria
  5. cladeOrnithomimosauria
  6. familyDeinocheiridae
  7. genusDeinocheirus
  8. speciesDeinocheirus mirificus

Taxonomic status: Valid

Fossil record

Cast of the giant forelimbs of the Deinocheirus mirificus holotype MPC-D 100/18 at the Natural History Museum, London.Image credit: Jacek Plewa, CC BY-SA 3.0, via Wikimedia Commons (unmodified except resizing), Natural History Museum, LondonCC BY-SA 3.0 (unmodified)Source (opens in a new tab)
Specimens
Catalog numberStatusInstitutionFound
MPC-D 100/18HolotypeInstitute of Paleontology, Mongolian Academy of Sciences (MPC)1965
MPC-D 100/127Referred specimenInstitute of Paleontology, Mongolian Academy of Sciences (MPC)2009
MPC-D 100/128Referred specimenInstitute of Paleontology, Mongolian Academy of Sciences (MPC)2006

What has been found

Holotype: MPC-D 100/18

  • Preserved
  • Partial
  • Reconstructed
  • Unknown / not recorded

Holotype: MPC-D 100/18

Region by region (table)
Skeleton regions of Holotype: MPC-D 100/18
RegionState
SkullUnknown / not recorded
MandibleUnknown / not recorded
TeethUnknown / not recorded
Cervical vertebraeUnknown / not recorded
Dorsal vertebraeUnknown / not recorded
SacrumUnknown / not recorded
Caudal vertebraeUnknown / not recorded
RibsUnknown / not recorded
GastraliaUnknown / not recorded
Scapula / shoulder girdlePreserved
HumerusPreserved
Forearm (radius / ulna)Preserved
Hand (manus)Preserved
PelvisUnknown / not recorded
FemurUnknown / not recorded
Tibia / fibulaUnknown / not recorded
Foot (pes)Unknown / not recorded

Referred specimen: MPC-D 100/127

Region by region (table)
Skeleton regions of Referred specimen: MPC-D 100/127
RegionState
SkullUnknown / not recorded
MandibleUnknown / not recorded
TeethUnknown / not recorded
Cervical vertebraeUnknown / not recorded
Dorsal vertebraeUnknown / not recorded
SacrumUnknown / not recorded
Caudal vertebraeUnknown / not recorded
RibsUnknown / not recorded
GastraliaUnknown / not recorded
Scapula / shoulder girdleUnknown / not recorded
HumerusUnknown / not recorded
Forearm (radius / ulna)Preserved
Hand (manus)Preserved
PelvisUnknown / not recorded
FemurUnknown / not recorded
Tibia / fibulaUnknown / not recorded
Foot (pes)Unknown / not recorded
Life-size replica of the restored Deinocheirus skull and neck vertebrae at the KIGAM Geological Museum, South Korea.Image credit: Jun-Hyeok Jang, CC BY-SA 4.0, via Wikimedia Commons (unmodified except resizing), KIGAM Geological MuseumCC BY-SA 4.0 (unmodified)Source (opens in a new tab)

All specimens

Discovery

Year described
1970
Described by
Halszka Osmólska & Ewa Roniewicz
Type specimen
MPC-D 100/18

Discovery timeline

  1. 1965 · First material found

    Giant arms found at Altan Uul III

    The Polish-Mongolian expedition collects a pair of 2.4 m forelimbs.

    People: Zofia Kielan-Jaworowska

  2. 1970 · Formally described

    Osmólska and Roniewicz name Deinocheirus

    The "terrible hand" is named with its own family.

    People: Halszka Osmólska, Ewa Roniewicz

  3. 2014 · Major study

    Deinocheirus mystery solved

    Lee and colleagues describe two new skeletons revealing the whole animal.

    People: Yuong-Nam Lee, Philip J. Currie

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 (opens in a new tab)
  2. (2026). Wikipedia: Deinocheirus. Wikipedia (English), accessed 2026-09-23. https://en.wikipedia.org/wiki/Deinocheirus (opens in a new tab)
  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 (opens in a new tab)
  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. doi:10.1038/nature13874 (opens in a new tab)
  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.