Open Paleo

Ornithomimosauria

Barsbold, 1976 Type genus Ornithomimus

Its genera lived 143.1–66.0 million years ago Early Cretaceous–Late Cretaceous
Early Cretaceous and Late Cretaceous stages

Ornithomimosauria, the "ostrich dinosaurs," is a group of theropod dinosaurs that bore a superficial resemblance to modern ostriches. Its members lived during the Cretaceous of Laurasia, now Asia, Europe, and North America, with possible records from Africa, first appearing in the Early Cretaceous and persisting until the close of the period. The most primitive forms, such as Pelecanimimus and Shenzhousaurus, retained small teeth, while the more derived species of the family Ornithomimidae, including Gallimimus and Struthiomimus, had toothless beaks. Ornithomimosaurs were lightly built and long-limbed, with feathered bodies and long, powerful hind legs that likely made them among the fastest of all dinosaurs. Numerous specimens preserving gastroliths in the gut, together with their peculiar hook-like hands, suggest that most were herbivores or omnivores rather than the carnivores typical of theropods.

Under dispute

The higher placement of Ornithomimosauria within Coelurosauria is unsettled. It is retained within Arctometatarsalia, the grouping proposed on arctometatarsalian-foot evidence by Holtz (1994) and redefined by Holtz (1996) as a stem-based clade anchored on Ornithomimus. Meso and colleagues (2024) report that recent studies instead recover Ornithomimosauria as the earliest-diverging branch of Maniraptoriformes, though their own analysis displaces Ornithomimosauria from it in favor of Alvarezsauria. Cau (2024) recovers a third arrangement, pairing Ornithomimosauria with Therizinosauroidea as sister taxa outside Maniraptora. The node is retained conservatively at its current position.

Diagnosis

  1. Elongate cervical vertebrae forming a long, gracile neck
  2. Reduced or absent dentition, with a keratinous beak in derived members
  3. Small, lightly built skull with large orbits
  4. Long, slender, cursorial hindlimbs
  5. Manus with subequal, elongate metacarpals and weakly curved unguals

Clades within Ornithomimosauria

Genera placed directly in Ornithomimosauria

  • Arkansaurus Hunt & Quinn, 2018 Albian (113.2–100.5 Ma)United States
  • Beishanlong Makovicky et al., 2010 Aptian (121.4–113.2 Ma)Chinaunder dispute
  • Harpymimus Barsbold & Perle, 1984 Albian (113.2–100.5 Ma)Mongoliaunder dispute
  • Hexing Jin et al., 2012 Barremian (125.8–121.4 Ma)China
  • Kinnareemimus Buffetaut et al., 2009 Valanginian–Hauterivian (137.1–125.8 Ma)Thailandunder dispute
  • Nqwebasaurus de Klerk et al., 2000 Berriasian–Valanginian (143.1–132.6 Ma)South Africaunder dispute
  • Pelecanimimus Pérez-Moreno et al., 1994 Barremian (125.8–121.4 Ma)Spain
  • Shenzhousaurus Ji et al., 2003 Barremian (125.8–121.4 Ma)China
  • Tyrannomimus Hattori et al., 2023 Aptian (121.4–113.2 Ma)Japanunder dispute

References

  1. Barsbold, R. (1976). On the evolution and systematics of the late Mesozoic dinosaurs. Transactions of the Joint Soviet-Mongolian Paleontological Expedition 3: 68-75.

    Diagnosed the infraorder Ornithomimosauria, crediting the name to Barsbold (1974).

    barsbold1976b
  2. Barsbold, R. (1974). Poyedinok dinozavrov [Dueling dinosaurs]. Priroda 2: 81-83.

    The 1974 Barsbold paper credited with the name Ornithomimosauria in Barsbold (1976).

    barsbold1974a
  3. Lee, Y. N.; Barsbold, R.; Currie, P. J.; Kobayashi, Y.; Lee, H. J.; Godefroit, P.; Escuillié, F. O.; Chinzorig, T. (2014). Resolving the long-standing enigmas of a giant ornithomimosaur Deinocheirus mirificus. Nature 515(7526): 257-260. doi:10.1038/nature13874

    Redescribed Deinocheirus and recovered Ornithomimosauria as two lineages, Deinocheiridae and Ornithomimidae.

    lee2014a
  4. Holtz, T. R. (1994). The phylogenetic position of the Tyrannosauridae: implications for theropod systematics. Journal of Paleontology 68: 1100-1117.

    Proposed Arctometatarsalia on arctometatarsalian-foot evidence, recovering Ornithomimosauria within it as sister to Troodontidae in Bullatosauria.

    holtz1994a
  5. Holtz, T. R. (1996). Phylogenetic taxonomy of the Coelurosauria (Dinosauria: Theropoda). Journal of Paleontology 70(3): 536-538. Cambridge University Press (CUP). doi:10.1017/s0022336000038506

    Replaced the apomorphy-based definition of Arctometatarsalia with a stem-based one anchored on Ornithomimus, and coined Maniraptoriformes.

    holtz1996a
  6. Cau, A. (2024). A Unified Framework for Predatory Dinosaur Macroevolution. Bollettino della Società Paleontologica Italiana 63(1): 1-19. doi:10.4435/BSPI.2024.08

    Recovered Ornithomimosauria as the sister group of Therizinosauroidea, both outside Maniraptora.

    cau2024a
  7. Meso, J. G.; Pol, D.; Chiappe, L.; Qin, Z.; Díaz-Martínez, I.; Gianechini, F.; Apesteguía, S.; Makovicky, P. J.; Pittman, M. (2024). Body size and evolutionary rate analyses reveal complex evolutionary history of Alvarezsauria. Cladistics 41(2): 135-155. Wiley. doi:10.1111/cla.12600

    Treats an early-diverging maniraptoriform position for Ornithomimosauria as the prevailing view, recovering Alvarezsauria in that position instead.

    meso2024a