Open Paleo

Eutyrannosauria

Delcourt & Grillo, 2018

Its genera lived 83.6–66.0 million years ago Late Cretaceous
Late Cretaceous stages

Eutyrannosauria is a clade of large-bodied tyrannosauroid theropod dinosaurs of the Northern Hemisphere, encompassing the family Tyrannosauridae together with its closest non-tyrannosaurid relatives, such as the eastern North American genera Dryptosaurus and Appalachiosaurus (Voris and colleagues, 2025). The southwestern North American Bistahieversor is the sister of Tyrannosauridae in the analysis of Delcourt and Grillo (2018) but falls within Tyrannosaurinae in that of Voris and colleagues (2025). It was defined to set these advanced, often gigantic northern forms apart from the more basal, globally distributed tyrannosauroids. Members are distinguished by their great size and by prominent cranial ornamentation, including roughened, ridge-bearing nasal bones. Powers and colleagues (2026) instead recover a family Dryptosauridae, including Dryptosaurus, in all their implied-weights analyses.

Diagnosis

  1. Rugose nasals with cornual ornamentation
  2. Lacrimal with an inflated cornual process that expands dorsally during ontogeny
  3. Anteroposteriorly expanded dorsal process of the quadratojugal
  4. Pneumatic recess on the anterior surface of the quadrate condyles
  5. Medial margins of the distal condyle and diaphysis of metatarsal III aligned (not offset)

Clades within Eutyrannosauria

Genera placed directly in Eutyrannosauria

  • Appalachiosaurus Carr et al., 2005 Campanian (83.6–72.2 Ma)United States
  • Bistahieversor Carr & Williamson, 2010 Campanian (83.6–72.2 Ma)United States
  • Dryptosaurus Marsh, 1877 Maastrichtian (72.2–66.0 Ma)United States
  • Nanotyrannus Disputed Bakker et al., 1988 Maastrichtian (72.2–66.0 Ma)United States
  • Stygivenator Disputed Olshevsky et al., 1995 Maastrichtian (72.2–66.0 Ma)United Statesincertae sedis

References

  1. Delcourt, R.; Grillo, O. N. (2018). Tyrannosauroids from the Southern Hemisphere: implications for biogeography, evolution, and taxonomy. Palaeogeography, Palaeoclimatology, Palaeoecology 511: 379-387. doi:10.1016/j.palaeo.2018.09.003

    Erected Eutyrannosauria as the least inclusive clade containing Tyrannosaurus rex and Dryptosaurus, with two unambiguous synapomorphies.

    delcourt2018a
  2. Voris, J. T.; Zelenitsky, D. K.; Kobayashi, Y.; Modesto, S. P.; Therrien, F.; Tsutsumi, H.; Chinzorig, T.; Tsogtbaatar, K. (2025). A new Mongolian tyrannosauroid and the evolution of Eutyrannosauria. Nature 642(8069): 973-979. Springer Science and Business Media LLC. doi:10.1038/s41586-025-08964-6

    Uses Eutyrannosauria (Delcourt and Grillo, 2018) as an established clade and recovers Khankhuuluu mongoliensis as its immediate sister taxon.

    voris2025a
  3. Powers, M. J.; Napoli, J. G.; Coppock, C. C.; Sharpe, H. S.; Garros, C. W.; Demers-Potvin, A. V.; Raun, G. S.; Stock, J. C.; Miyashita, T.; Currie, P. J. (2026). A new albertosaurine from the Oldman Formation, Alberta, Canada, illuminates ambiguity between albertosaurine and tyrannosaurine characteristics. Journal of Vertebrate Paleontology e2728669. Informa UK Limited. doi:10.1080/02724634.2026.2728669

    Described a new albertosaurine and recovered Dryptosauridae as a clade in all implied-weights analyses, in place of Eutyrannosauria.

    powers2026a