Mononykus
muh-NON-ih-kus
"one claw"
- Lived
- 84 to 66 million years ago, Late Cretaceous
- Diet
- Carnivore
- Length
- about 1 m (3 ft)
- Group
- Theropods, Alvarezsauridae
- Found in
- Mongolia
- Named by
- Perle et al. 1993
Size comparison
To scale
Scale in metersOutline: typical theropod shape
Where its fossils were found
The evidence
Today
75 million years ago
Habitat
The Nemegt Formation in Mongolia records rivers and broad floodplains. Tarbosaurus, Therizinosaurus and Deinocheirus inhabited this landscape.
Field notes
About Mononykus
What it was like
Mononykus was a small, lightly built dinosaur about 1 meter (3 feet) long, with long thin legs and probably a coat of feathers. Its arms were short and stout, each ending in a single large claw.
Scientists think it used those claws to break into insect nests, such as termite mounds, a bit like an anteater.
Its world
It lived in the Late Cretaceous, in what is now Mongolia. Its fossils come from the Nemegt and Djadokhta formations, where it lived alongside Velociraptor, Protoceratops, Tarbosaurus and Therizinosaurus.
How it was found
Perle and colleagues named Mononykus in 1993. It was at first thought to be an early bird, but it is now known to be an alvarezsaurid, a small branch of feathered dinosaurs. Five finds are known.
Field gallery
More views of Mononykus
Scenes reconstructed from the available fossil evidence.
1 of 3
Lived alongside
Found in the same rock formations
A rock formation can hold fossils laid down millions of years apart, so not every animal here met Mononykus.
The evidence
The science behind Mononykus
Which parts of the picture come from its own bones, and which come from its relatives.
From its own fossils
- Its skeleton has very short, stout arms, each with a single large functional claw.
- The forelimb joints allowed a strong hook-and-pull movement that probably helped open tough insect nests.
Borrowed from relatives
- A feather coat is inferred from relatives such as Shuvuuia, which preserves feather-like fibers.
Still unknown
- Which insects it ate.
- Its feather colors and patterns.
- Whether it had a long tongue for collecting insects.
Discovery timeline
- 1993Named itPerle et al.
- 1999Close relativeSchweitzer et al.
- 2005How it fedSenter
Key papers
The research behind what we know of Mononykus
Named it
Described a small dinosaur with short, powerful arms and a single stout claw, initially interpreting it as a flightless bird.
Correction: Flightless bird from the Cretaceous of Mongolia. Nature 363: 188
No link available
Close relative
Studied tiny fibers preserved with Shuvuuia and interpreted them as feather-like structures, supporting feathered restorations of related dinosaurs.
Beta-keratin specific immunological reactivity in feather-like structures of the Cretaceous Alvarezsaurid,Shuvuuia deserti. Journal of Experimental Zoology 285: 146-157
Read the paper : Beta-keratin specific immunological reactivity in feather-like structures of the Cretaceous Alvarezsaurid,Shuvuuia deserti (opens in a new tab)How it fed
Tested the forelimb joints and found movements suited to pulling apart insect nests, much like an anteater's claws.
Function in the stunted forelimbs of Mononykus olecranus (Theropoda), a dinosaurian anteater. Paleobiology 31: 373-381
Read the paper : Function in the stunted forelimbs of Mononykus olecranus (Theropoda), a dinosaurian anteater (opens in a new tab)
Close relatives
Other members of Alvarezsauridae
Sources: Wikidata