Open Paleo

Thescelosaurinae

Sternberg, 1937 Type genus Thescelosaurus

Its genera lived 121.4–66.0 million years ago Early Cretaceous–Late Cretaceous
Early Cretaceous and Late Cretaceous stages

Thescelosaurinae is one of the two subfamilies of Thescelosauridae, a group of small, plant-eating neornithischian dinosaurs from the Cretaceous of North America and East Asia. It unites Thescelosaurus and Parksosaurus, with Notohypsilophodon in the analysis of Madzia and colleagues (2021); other analyses add small Asian forms, among them Jeholosaurus and Changchunsaurus, previously classified in Jeholosauridae (Fonseca and colleagues, 2024), and the newly named Doolysaurus (Jung and colleagues, 2026), and it is recognized as the counterpart to the smaller, burrow-associated Orodrominae. Thescelosaurus, the largest known thescelosaurid, is notably robust and large-bodied, though several other thescelosaurine genera, including Haya, Changchunsaurus, and Doolysaurus, were much smaller. Like other thescelosaurids, they are thought to have been highly selective browsers that fed mainly on soft, pulpy plant material.

Diagnosis

  1. Two supraorbital bones that remain unfused
  2. Dorsally projecting, finger-like process on the surangular
  3. Robust, comparatively large-bodied build relative to orodromines
  4. Ilium with a sinuous dorsal margin in derived members

Genera placed directly in Thescelosaurinae

  • Changchunsaurus Zan et al., 2005 Aptian–Albian (121.4–100.5 Ma)China
  • Doolysaurus Jung et al., 2026 Albian–Cenomanian (113.2–93.9 Ma)South Koreaunder dispute
  • Fona Avrahami et al., 2024 Cenomanian (100.5–93.9 Ma)United States
  • Haya Makovicky et al., 2011 Santonian–Campanian (85.7–72.2 Ma)Mongoliaunder dispute
  • Parksosaurus Sternberg, 1937 Maastrichtian (72.2–66.0 Ma)Canadaunder dispute
  • Thescelosaurus Gilmore, 1913 Maastrichtian (72.2–66.0 Ma)United States

References

  1. Sternberg, C. M. (1937). Classification of Thescelosaurus, with a description of a new species. Proceedings of the Geological Society of America 1936: 375.

    Origin of the family-group name (Thescelosauridae), and by coordination the subfamily Thescelosaurinae.

    sternberg1937a
  2. Sternberg, C. M. (1940). Thescelosaurus edmontonensis, n. sp., and classification of the Hypsilophodontidae. Journal of Paleontology 14: 481-494.

    Named Thescelosaurinae as a new subfamily.

    sternberg1940c
  3. Madzia, D.; Arbour, V. M.; Boyd, C. A.; Farke, A. A.; Cruzado-Caballero, P.; Evans, D. C. (2021). The phylogenetic nomenclature of ornithischian dinosaurs. PeerJ 9: e12362. doi:10.7717/peerj.12362

    Provides the modern phylogenetic definition of Thescelosaurinae.

    madzia2021a
  4. Fonseca, A. O.; Reid, I. J.; Venner, A.; Duncan, R. J.; Garcia, M. S.; Müller, R. T. (2024). A comprehensive phylogenetic analysis on early ornithischian evolution. Journal of Systematic Palaeontology 22: 2346577. doi:10.1080/14772019.2024.2346577

    Recovered Jeholosaurus and Changchunsaurus within Thescelosaurinae, rendering Jeholosauridae inapplicable.

    fonseca2024a
  5. Jung, J.; Kim, M.; Jo, H.; Clarke, J. A. (2026). A new dinosaur species from Korea and its implications for early-diverging neornithischian diversity. Fossil Record 29(1): 87-113. Pensoft Publishers. doi:10.3897/fr.29.178152

    Described Doolysaurus and recovered it and other small Asian taxa within Thescelosaurinae in the Fonseca dataset.

    jung2026a