Project 3298: S. J. Nesbitt, R. K. Denton, M. A. Loewen, S. L. Brusatte, N. D. Smith, A. H. Turner, J. I. Kirkland, A. T. McDonald, D. G. Wolfe. 2019. A mid-Cretaceous tyrannosauroid and the origin of North American end-Cretaceous dinosaur assemblages. Nature Ecology & Evolution. 3 (6):892-899.
Specimen: † Suskityrannus hazelae (MSM:P6178)
View: cross section


Late Cretaceous dinosaur assemblages of North America—characterized by gigantic tyrannosaurid predators, and large-bodied herbivorous ceratopsids and hadrosaurids—were highly successful from around 80 million years ago (Ma) until the end of the ‘Age of Dinosaurs’ 66 Ma. However, the origin of these iconic faunas remains poorly understood because of a large, global sampling gap in the mid-Cretaceous, associated with an extreme sea-level rise. We describe the most complete skeleton of a predatory dinosaur from this gap, which belongs to a new tyrannosauroid theropod from the Middle Turonian (~92 Ma) of southern Laramidia (western North America). This taxon, Suskityrannus hazelae gen. et sp. nov., is a small-bodied species phylogenetically intermediate between the oldest, smallest tyrannosauroids and the gigantic, last-surviving tyrannosaurids. The species already possesses many key features of the tyrannosaurid bauplan, including the phylogenetically earliest record of an arctometatarsalian foot in tyrannosauroids, indicating that the group developed enhanced cursorial abilities at small body size. Suskityrannus is part of a transitional Moreno Hill (that is, Zuni) dinosaur assemblage that includes dinosaur groups that became rare or were completely absent in North America around the final 15 Myr of the North American Cretaceous before the end-Cretaceous mass extinction, as well as small-bodied forebears of the large-bodied clades that dominated at this time.

Read the article »

Article DOI: 10.1038/s41559-019-0888-0

Project DOI: 10.7934/P3298,
This project contains
  • 2 Media
  • 3 Documents
  • 1 Taxon
  • 1 Specimen
Total size of project's media files: 1.61G

Download Project SDD File
Currently Viewing:
MorphoBank Project 3298

    Authors' Institutions

    • Western Science Center, Hemet

    • University of Edinburgh

    • University of Utah

    • Virginia Tech (Virginia Polytechnic Institute and State University)

    • Natural History Museum of Los Angeles County

    • Natural History Museum of Utah

    • Stony Brook University

    • GeoConcepts Engineering (a Terracon Company)

    • Utah Geological Survey

    • Zuni Dinosaur Institute for Geosciences


    member name taxa specimens media
    Sterling Nesbitt
    Project Administrator

    Project has no matrices defined.

    Project views

    type number of views Individual items viewed (where applicable)
    Total project views6387
    Project overview1145
    Media views2234Media search (1685 views); M669115 (273 views); M595506 (276 views);
    Taxon list627
    Views for media list547
    Specimen list962
    Documents list507

    Project downloads

    type number of downloads Individual items downloaded (where applicable)
    Total downloads from project177
    Project downloads166
    Media downloads7M595506 (6 downloads); M669115 (1 download);
    Document downloads4TNT data matrix used for the phylogenetic analysis. Brusatte and Carr 2016 tyrannosauroid phylogeny dataset with Suskityrannus (1 download); TNT data matrix used for the phylogenetic analysis. Brusatte et al. 2014 theropod dataset with Suskityrannus (3 downloads);