Open Paleo

Albertonykus

Longrich & Currie, 2009 al-BUHR-toh-NYE-kuss

Named after Alberta, Canada, combined with Greek 'onyx' (genitive 'onykos') meaning 'claw'; meaning 'Alberta claw'

72.2–66.0 million years ago Maastrichtian, Late Cretaceous
Late Cretaceous stages

Albertonykus is an extinct genus of alvarezsaurid dinosaur from the Maastrichtian-age (Upper Cretaceous) rocks of the Horseshoe Canyon Formation of Alberta, Canada. It is known from forelimb and hindlimb remains from multiple individuals. All but two of the specimens come from a bonebed dominated by Albertosaurus, located at the top of Unit 4 of the Horseshoe Canyon Formation, dating to ~68.5 million years ago.

Diagnosis

  1. Ulna extremely broad, maximum width 35% of length
  2. Distinct tubercle on medial margin of ulna, absent or only weakly developed as a small ridge in other alvarezsaurs
  3. Manual ungual I with Y-shaped lateral grooves, absent in both Asian and South American alvarezsaurs
  4. Ventral groove of manual ungual I extends proximally to the level of the ventral foramina, further than in Mononykus
  5. Metatarsal III shaft with sharp longitudinal ventral keel and flat, unexpanded dorsal surface, contrasting with rounded ventral and expanded dorsal surfaces of Asian taxa

Species

Albertonykus borealis Longrich & Currie, 2009

Type species

Means 'north', referring to the northern location of the discovery in Alberta, Canada.

Holotype
TMP 2001.045.0091 , Royal Tyrrell Museum of Paleontology
Material
Left ulna.
Horizon
Tolman Member, Horseshoe Canyon Formation, Maastrichtian, Late Cretaceous , 72.2–66.0 million years ago
Locality
Albertosaurus Bonebed, Dry Island Buffalo Jump, Alberta, Canada

References

  1. Longrich, N. R.; Currie, P. J. (2009). Albertonykus borealis, a new alvarezsaur (Dinosauria: Theropoda) from the Early Maastrichtian of Alberta, Canada: implications for the systematics and ecology of the Alvarezsauridae. Cretaceous Research 30(1): 239-252. Elsevier BV. doi:10.1016/j.cretres.2008.07.005 longrich2009b
  2. Larson, D. W.; Brinkman, D. B.; Bell, P. R. (2010). Faunal assemblages from the upper Horseshoe Canyon Formation, an early Maastrichtian cool-climate assemblage from Alberta, with special reference to the Albertosaurus sarcophagus bonebed. Canadian Journal of Earth Sciences 47(9).

    Places the Albertosaurus bonebed at the top of unit 4.

    larson2010a
  3. Eberth, D. A.; Braman, D. R. (2012). A revised stratigraphy and depositional history for the Horseshoe Canyon Formation (Upper Cretaceous), southern Alberta plains. Canadian Journal of Earth Sciences 49(9): 1053-1086. Canadian Science Publishing. doi:10.1139/e2012-035

    Source of the Tolman Member, unit 4 of the revised Horseshoe Canyon stratigraphy.

    eberth2012a
  4. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Theropods. Princeton University Press.

    Source of the hip height estimate, and the appearance features.

    jones2026c