Open Paleo

Atrociraptor

Currie & Varricchio, 2004 Ah-TROSS-ee-rap-tor /əˌtrɑːsiˈræptər/

From Latin 'atrox' meaning 'savage' or 'cruel' and 'raptor' meaning 'robber' or 'thief', meaning 'savage robber'.

83.6–66.0 million years ago Campanian–Maastrichtian, Late Cretaceous
Late Cretaceous stages

Atrociraptor is a genus of dromaeosaurid dinosaur that lived during the Late Cretaceous in what is now Alberta, Canada. The first specimen, a partial skull, was discovered in 1995 by the fossil collector Wayne Marshall in the Horseshoe Canyon Formation, about 5 km (3 mi) from the Royal Tyrrell Museum of Palaeontology where it was brought for preparation. In 2004, the specimen became the holotype of the new genus and species Atrociraptor marshalli; the generic name is Latin for "savage robber", and the specific name refers to Marshall. The holotype consists of the premaxillae (frontmost bones of the upper jaw), a maxilla (main bone of the upper jaw), the dentaries (tooth-bearing bones of the lower jaw), associated teeth, and other skull fragments. Isolated teeth from the same formation have since been assigned to Atrociraptor.

Under dispute

Atrociraptor was originally described as a velociraptorine (Currie and Varricchio, 2004) but is recovered within Saurornitholestinae, as the sister taxon of Saurornitholestes, by most recent analyses (Longrich and Currie, 2009; Currie and Evans, 2019; Powers and colleagues, 2022), the placement followed.

Diagnosis

  1. Shorter, deeper face than Saurornitholestes and Velociraptor; subnarial body of premaxilla taller than its anteroposterior length
  2. Internarial and maxillary processes of premaxilla subparallel and oriented more dorsally than posteriorly
  3. Maxillary fenestra larger than in any other velociraptorines and positioned directly above the promaxillary fenestra rather than well behind it
  4. Maxillary teeth more strongly inclined toward the throat (posteroventrally) than in all other dromaeosaurids except Bambiraptor and Deinonychus
  5. Maxillary dentition essentially isodont with no replacement gaps and minimal height variation between adjacent teeth

Species

Atrociraptor marshalli Currie & Varricchio, 2004

Type species

Named for Wayne Marshall, the fossil collector who discovered the holotype specimen in 1995 in the Horseshoe Canyon Formation of Alberta.

Holotype
TMP 1995.166.0001 , Royal Tyrrell Museum of Paleontology
Material
Partial skull including premaxillae, right maxilla, right dentary, portions of left dentary, teeth, and numerous bone fragments
Horizon
Horseshoe Canyon Formation, Campanian–Maastrichtian, Late Cretaceous , 83.6–66.0 million years ago
Locality
5 km west of the Royal Tyrrell Museum of Palaeontology, Alberta, Canada

References

  1. Currie, P. J.; Varricchio, D. J. (2004). A new dromaeosaurid from the Horseshoe Canyon Formation (Upper Cretaceous) of Alberta, Canada. Feathered Dragons: Studies on the Transition from Dinosaurs to Birds (Currie, P. J.; Koppelhus, E. B.; Shugar, M. A.; Wright, J. L., eds.) 112-132. Indiana University Press, Bloomington. currie2004a
  2. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Theropods. Princeton University Press.

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

    jones2026c
  3. Longrich, N. R.; Currie, P. J. (2009). A microraptorine (Dinosauria-Dromaeosauridae) from the Late Cretaceous of North America. Proceedings of the National Academy of Sciences 106(13): 5002-5007. Proceedings of the National Academy of Sciences. doi:10.1073/pnas.0811664106

    Named Saurornitholestinae, recovering Atrociraptor as sister to Saurornitholestes in a new dromaeosaurid clade

    longrich2009a
  4. Powers, M. J.; Fabbri, M.; Doschak, M. R.; Bhullar, B. A. S.; Evans, D. C.; Norell, M. A.; Currie, P. J. (2022). A new hypothesis of eudromaeosaurian evolution: CT scans assist in testing and constructing morphological characters. Journal of Vertebrate Paleontology 41(5). doi:10.1080/02724634.2021.2010087

    Recovered Atrociraptor within Saurornitholestinae as the sister taxon of Saurornitholestes

    powers2022a
  5. Currie, P. J.; Evans, D. C. (2019). Cranial Anatomy of New Specimens of Saurornitholestes langstoni (Dinosauria, Theropoda, Dromaeosauridae) from the Dinosaur Park Formation (Campanian) of Alberta. The Anatomical Record 303(4): 691-715. Wiley. doi:10.1002/ar.24241

    Recovered Atrociraptor within Saurornitholestinae.

    currie2019a