Open Paleo

Saurornithoides

Osborn, 1924 saw-ROR-ni-THOY-deez /sɔːˌrɔːrnɪˈθɔɪdiːz/

From Greek 'sauros' meaning 'lizard', 'ornis' (stem 'ornith') meaning 'bird', and 'eidos' meaning 'form' or 'resemblance', referring to its bird-like skull.

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

Saurornithoides is a genus of troodontid maniraptoran dinosaur, which lived during the Late Cretaceous period. These creatures were predators, which could run fast on their hind legs and had excellent sight and hearing. The name is derived from the Greek stems saur~ (lizard), ornith~ (bird) and eides (form), referring to its bird-like skull.

Diagnosis

  1. Diapsid skull with five craniofacial fenestrations and one mandibular fenestration
  2. Long pointed rostrum suggesting avian affinities but reptilian/megalosaurian in form
  3. Teeth subhomodont, flattened, serrate on posterior borders only (unlike Velociraptor)
  4. Four premaxillary and fifteen maxillary teeth with uniform replacement and closely compacted crowns
  5. Hind limb with four digits of typical megalosaurian type; terminal claw 30 mm recurved

Species

Saurornithoides mongoliensis Osborn, 1924

Type species

Named for Mongolia, where the holotype was discovered in the Djadokhta Formation.

Holotype
AMNH 6516 , American Museum of Natural History
Material
Skull and jaws, found in concretion with weathering; series of vertebrae with pelvis and hind limb parts in separate concretion may belong to same individual.
Horizon
Bayn Dzak Member, Djadokhta Formation, Campanian, Late Cretaceous , 83.6–72.2 million years ago
Locality
Bayan Zag, Ömnögovi, Mongolia Norell and colleagues (2009) record that "the precise locality at the Flaming Cliffs where the specimen was collected was not recorded", the collection dating to 1923.

Synonyms of the genus

Name Type Reason
Ornithoides nomen nudum Osborn mentioned this name in a 1924 popular publication without a description, leaving it an invalid nomen nudum; the formal description used Saurornithoides.

Notable specimens

  • IVPP V1059

    Institute of Vertebrate Paleontology and Paleoanthropology ontogeny

    A juvenile specimen from the Upper Cretaceous of northern China whose highly ossified hindlimb suggested that Saurornithoides and other troodontids were well developed at birth and probably required little to no parental care, giving insight into troodontid life history.

    Currie & Peng (1993)

References

  1. Currie, P. J.; Peng, J. H. (1993). A juvenile specimen of Saurornithoides mongoliensis from the Upper Cretaceous of northern China. Canadian Journal of Earth Sciences 30(10): 2224-2230. doi:10.1139/e93-193 currie1993b
  2. Osborn, H. F. (1924). Three new Theropoda, Protoceratops zone, central Mongolia. American Museum Novitates 144: 1-12. osborn1924b
  3. Norell, M. A.; Makovicky, P. J.; Bever, G. S.; Balanoff, A. M.; Clark, J. M.; Barsbold, R.; Rowe, T. (2009). A Review of the Mongolian Cretaceous Dinosaur Saurornithoides (Troodontidae: Theropoda). American Museum Novitates 3654: 1-63. American Museum of Natural History (BioOne sponsored). doi:10.1206/648.1

    Redescribes the holotype and fixes its provenance to the Djadokhta Formation at Bayan Zag, noting that the precise spot at the Flaming Cliffs went unrecorded.

    norell2009a
  4. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Theropods. Princeton University Press.

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

    jones2026c