Avimimus

Lore & Background

The remains of Avimimus were recovered by Russian paleontologists and officially described by Dr. Sergei Kurzanov in 1981. The fossils were initially described as coming from the Djadokhta Formation, but later research (e.g., Watabe et al., 2000) re-assigned them to the Nemegt Formation. The type species is A. portentosus. Because no tail was found with the original find, Kurzanov mistakenly concluded that Avimimus lacked a tail, but subsequent finds containing caudal vertebrae confirmed its presence. A second nearly complete specimen was discovered in 1996 and described in 2000 by Watabe and colleagues, who also identified small theropod footprints in the same area as belonging to Avimimus.

In 2008, a team headed by Phil Currie reported an extensive bonebed of Avimimus sp. fossils in the Nemegt Formation, containing abundant bones of at least ten individuals, all adult or subadult. The adults showed little size variation, suggesting determinate growth, and the team suggested the individuals were gregarious in life, possibly forming age-segregated groups for lekking or flocking. The preservation suggests rapid burial by water flow. In 2018, Avimimus sp. was named as a new species, A. nemegtensis, with its formal description published in 2019.

Reader's Guide

Avimimus holds a notable place in dinosaur paleontology due to its highly bird-like anatomy and the early controversy over its relationship to birds. Kurzanov originally argued that Avimimus, rather than Archaeopteryx, was close to the direct ancestor of modern birds, a view not supported by later phylogenetic analyses, which place it within the oviraptorosaurs, more primitive than Archaeopteryx. The presence of quill knobs on the ulna, reported by Kurzanov and confirmed by Chiappe, suggests feathers, though most paleontologists do not believe Avimimus could fly. Its long, slender legs and fused hand bones indicate it was a specialized runner. The discovery of a bonebed with multiple individuals suggests gregarious behavior, offering insights into the social structure of oviraptorosaurs. The uncertainty about its diet—herbivore, omnivore, or insectivore—and the disputed provenance of its fossils highlight the ongoing refinement of knowledge about this genus. Avimimus remains a key taxon for understanding the evolution of bird-like traits in non-avian dinosaurs.

Did You Know?

• Kurzanov originally thought Avimimus lacked a tail, but later finds confirmed it had caudal vertebrae.
• The bonebed of Avimimus sp. contained at least ten individuals, all adult or subadult, suggesting gregarious behavior.
• Kurzanov described a ridge on the ulna, which later researchers (e.g., Chiappe & Witmer, 2002) interpreted as quill knobs indicating feather attachments.
• The species A. nemegtensis was formally described in 2019 from the Nemegt Formation.