Ceratonykus

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Ceratonykus, meaning “horned claw,” is a small alvarezsaurid dinosaur from Mongolia that lived about 72 million years ago in the Late Cretaceous. It is known from a single species, Ceratonykus oculatus, based on a fragmentary skeleton that includes part of the skull. The animal was described in 2009 by Vladimir Alifanov and Rinchen Barsbold. The holotype is MPC 100/124 and shows an adult with an incomplete skull and various other bones.

Ceratonykus was about 0.6 meters (roughly 2 feet) long and weighed around 1 kilogram. As an alvarezsaurid, it belonged to a group of small, likely insect-eating theropods with specialized forelimbs. Its exact place in the dinosaur family tree has been debated. For a time it was linked with Parvicursor and other alvarezsaurids, but some researchers have suggested different placements, and in 2022 some analyses even proposed that Ceratonykus might be the same as Parvicursor. Most views, however, keep it as a distinct alvarezsaurid genus.

Ceratonykus was found in the Barun Goyot Formation, dating to the Campanian stage of the Late Cretaceous. The rocks indicate a semi-arid environment with dunes and occasional lakes, and the formation has yielded several other dinosaurs, including other alvarezsaurids, ankylosaurs, ceratopsians, and dromaeosaurs.

One notable study of Ceratonykus looked at its braincase and suggested some bird-like brain features, especially in the areas tied to vision. This has contributed to ideas about how alvarezsaurids might have hunted or moved, including the possibility of climbing abilities in their ancestors. Overall, Ceratonykus is a small, bird-like, insect-eating dinosaur known from limited remains, with ongoing discussion about its precise relationship to other alvarezsaurids.