Mononykus
From Greek 'monos' (one) and 'onyx' (claw); meaning 'one claw', referring to its single functional forelimb claw.
Mononykus is a genus of alvarezsaurid dinosaur that lived during the Late Cretaceous in what is now Mongolia, specifically the Nemegt Formation. Mononykus was a very small theropod, estimated around 1 to 1.2 meters (3.3 to 3.9 ft) in length with a weight of 3.5 kilograms (7.7 lb). As in Shuvuuia, Mononykus likely developed a shaggy feathering. It was lightly built with long, thin legs and highly reduced and specialized forelimbs that were likely used for foraging termite mounds or other insect colonies.
Diagnosis
- Edentulous maxilla lacking accessory fenestra in antorbital fossa
- Short robust forelimb with single stout claw on manual digit I
- Massive short quadrangular carpometacarpus with no intermetacarpal space
- Carinate sternum with thick sternal carina
- Fibula does not reach tarsus
- Very long olecranon process of ulna with pronounced pectoral crest of humerus
- Single distal condyle of humerus positioned on cranial surface
Species
Mononykus olecranus Perle et al., 1993
Type species
From Greek 'olekranon' meaning 'elbow head', referring to the large olecranon process of the ulna.
- Holotype
- IGM N107/6 , Paleontological Center, Mongolian Academy of Sciences
- Material
- Posterior part of skull, most precaudal vertebrae, all four limbs, thoracic girdle, and portions of ilium and pubis
- Horizon
- Nemegt Formation, Maastrichtian, Late Cretaceous , 72.2–66.0 million years ago
- Locality
- Bügiin Tsav, Ömnögovi, Mongolia
Synonyms of the genus
| Name | Type | Reason |
|---|---|---|
| Mononychus | preoccupied | Name preoccupied by Mononychus (Coleoptera). |
Notable specimens
-
MPC-D 100/206
Paleontological Center, Mongolian Academy of Sciences Found 2008 by Korea-Mongolia International Dinosaur Expedition complementary
Referred Nemegt Formation specimen of seven caudal vertebrae with a partial left hindlimb, found at Altan Uul III. It preserves tail anatomy absent in the holotype, whose partial skeleton lacks a tail.
References
- Perle, A.; Norell, M. A.; Chiappe, L. M.; Clark, J. M. (1993). Flightless bird from the Cretaceous of Mongolia. Nature 362: 623-626. doi:10.1038/362623a0 perle1993a
- Perle, A.; Norell, M. A.; Chiappe, L. M.; Clark, J. M. (1993). Correction: Flightless bird from the Cretaceous of Mongolia. Nature 363: 188. doi:10.1038/363188a0 perle1993b
-
Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Theropods. Princeton University Press.
Source of the hip height estimate, and the appearance features.
jones2026c - Lee, S.; Park, J. Y.; Lee, Y. N.; Kim, S. H.; Lü, J.; Barsbold, R.; Tsogtbaatar, K. (2019). A new alvarezsaurid dinosaur from the Nemegt Formation of Mongolia. Scientific Reports 9(1): 15493. Springer Science and Business Media LLC. doi:10.1038/s41598-019-52021-y lee2019a