Open Paleo

Aepyornithomimus

Chinzorig et al., 2017 ee-PEE-or-NITH-o-MIEM-us

Named after Aepyornis (the extinct elephant bird) combined with Greek 'mimos' meaning 'mimic'; meaning 'Aepyornis mimic'

83.6–72.2 million years ago Campanian, Late Cretaceous
Late Cretaceous stages

Aepyornithomimus is a genus of ornithomimid theropod dinosaur from the Late Cretaceous Djadokhta Formation of Mongolia. It lived in the Campanian, around 75 million years ago, when the area is thought to have been a desert. The type and only species is A. tugrikinensis.

Diagnosis

  1. Unevenly developed pair of concavities on the posterior margin of distal tarsal III, with the medial concavity deeper than the lateral
  2. Robust distal articular caput of second metatarsal in dorsal view, nearly as wide as distal articulation of Mt III
  3. Unusual curved contact between proximal ends of Mt II and Mt IV (straight in all other ornithomimosaurs)
  4. Elongate fourth digit relative to derived ornithomimosaurs, with mediolaterally slender successive phalanges
  5. Medial condyle of phalanx IV-1 inclined laterally at ~35°, greater than in any other known ornithomimosaur
  6. Proximoventral ridge of phalanx II-1 forming a rounded curvature (rectilinear in other ornithomimosaurs)

Species

Aepyornithomimus tugrikinensis Chinzorig et al., 2017

Type species

Named for the Tögrögin Shiree locality of the Djadokhta Formation in Mongolia, where the holotype was discovered.

Holotype
MPC-D 100/130 , Paleontological Center, Mongolian Academy of Sciences
Material
Articulated left pes with astragalus (ascending process missing), complete calcaneum, and distal tarsal III
Horizon
Tugrugyin Member, Djadokhta Formation, Campanian, Late Cretaceous , 83.6–72.2 million years ago
Locality
Central Sayr, Ömnögovi, Mongolia

References

  1. Chinzorig, T.; Kobayashi, Y.; Tsogtbaatar, K.; Currie, P. J.; Watabe, M.; Barsbold, R. (2017). First Ornithomimid (Theropoda, Ornithomimosauria) from the Upper Cretaceous Djadokhta Formation of Tögrögiin Shiree, Mongolia. Scientific Reports 7(1). Springer Science and Business Media LLC. doi:10.1038/s41598-017-05272-6 chinzorig2017a
  2. Dashzeveg, D.; Dingus, L.; Loope, D. B.; Swisher, C. C., III; Dulam, T.; Sweeney, M. R. (2005). New stratigraphic subdivision, depositional environment, and age estimate for the Upper Cretaceous Djadokhta Formation, southern Ulan Nur Basin, Mongolia. American Museum Novitates 3498: 1-31. American Museum of Natural History. doi:10.1206/0003-0082(2005)498[0001:NSSDEA]2.0.CO;2

    Erects the Tugrugyin Member and describes its type section at Tögrögiin Shiree.

    dashzeveg2005a
  3. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Theropods. Princeton University Press.

    Source of the body length, mass, and hip height estimates.

    jones2026c