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Archaeornithoides

Elżanowski & Wellnhofer, 1992 AHR-kee-OR-ni-THOI-deez

From Greek 'archaios' meaning 'ancient', 'ornis' meaning 'bird', and '-oides' meaning 'resembling', translating to 'ancient bird-like'.

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

Archaeornithoides is a genus of maniraptoran theropod dinosaur of the Late Cretaceous of Mongolia.

Under dispute

Archaeornithoides is based on a fragmentary juvenile skull and was originally linked to troodontids and spinosaurids as a close bird relative (Elżanowski and Wellnhofer, 1992). Bever and Norell (2009) rejected the avialan placement and found only weak support for a troodontid position, noting complicating counter-evidence; the spinosaurid link is no longer supported. Given only weakly supported troodontid affinity on a juvenile holotype, it is placed conservatively at Maniraptora incertae sedis.

Diagnosis

  1. Maxilla with a major pit on the lateral surface of the nasal process and a rostromedial process recurved ventrally
  2. Large dorsal opening to the supraalveolar canal behind the base of the nasal process
  3. Broad palatal shelf enclosing a small rostral sinus and a large caudal sinus, shelf so expanded that subfenestral part of maxilla is distinctly broader than high
  4. Dentary with interdental septa descending labio-lingually and separated from the lingual wall by the paradental groove
  5. Maxillary teeth widely spaced, conical or only slightly compressed labio-lingually, lacking both serrations and carinae

Species

Archaeornithoides deinosauriscus Elżanowski & Wellnhofer, 1992

Type species

Means 'little dinosaur', alluding to the animal's small size for a dinosaur.

Holotype
ZPAL MgD-II/29 , Institute of Paleobiology, Polish Academy of Sciences
Material
Fragmentary skull comprising maxillae, dentaries, and palatal bones (right palatine best preserved); from a juvenile individual; total skull length estimated 5 cm
Horizon
Bayn Dzak Member, Djadokhta Formation, Campanian, Late Cretaceous , 83.6–72.2 million years ago
Locality
Bayan Zag, Ömnögovi, Mongolia Dashzeveg and colleagues (2005) list this genus under the Tugrugyin Shireh fauna in their Table 2, against their own body text and against Elżanowski and Wellnhofer (1992), who place the holotype at Bayan Zag. The table appears to be in error.

References

  1. Elżanowski, A.; Wellnhofer, P. (1992). A new link between theropods and birds from the Cretaceous of Mongolia. Nature 359(6398): 821-823. Springer Science and Business Media LLC. doi:10.1038/359821a0 elżanowski1992a
  2. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Theropods. Princeton University Press.

    Source of the body length estimate.

    jones2026c
  3. Bever, G. S.; Norell, M. A. (2009). The perinate skull of Byronosaurus (Troodontidae) with observations on the cranial ontogeny of paravian theropods. American Museum Novitates (3657): 1-51. doi:10.1206/650.1

    Rejected an avialan placement and found only weak support for a troodontid position for the fragmentary juvenile skull.

    bever2009a
  4. 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 dashzeveg2005a