Open Paleo

Styracosterna

Sereno, 1986

Its genera lived 143.1–66.0 million years ago Early Cretaceous–Late Cretaceous
Early Cretaceous and Late Cretaceous stages

Styracosterna is a clade of ankylopollexian ornithopod dinosaurs defined to include Iguanodon and all its relatives that are closer to it than to Camptosaurus. It encompasses the classic "iguanodont-grade" forms as well as the more derived Hadrosauriformes, which in turn contains the duck-billed hadrosaurids. Body size within the clade ranges widely, from small, lightly built, likely fast-running species known from the latest Cretaceous to some of the largest ornithopod dinosaurs that ever lived. The oldest known styracosternans date to the Late Jurassic of Europe, and by the Cretaceous the clade had spread worldwide, with hadrosaurids becoming among the dominant large plant-eaters of Late Cretaceous ecosystems across Asia, Europe, Africa, and the Americas.

Diagnosis

  1. Elongate, spur- or hatchet-shaped ossified sternal plate
  2. Conical, spike-like manual pollex ungual
  3. Elongate snout with an expanded, edentulous premaxilla
  4. Reduction of the phalanges in the lateral manual digits
  5. Hoof-like unguals on the pedal digits

Clades within Styracosterna

Genera placed directly in Styracosterna

  • Barilium Norman, 2010 Valanginian (137.1–132.6 Ma)United Kingdomunder dispute
  • Bayannurosaurus Xu et al., 2018 Aptian (121.4–113.2 Ma)China
  • Brighstoneus Lockwood et al., 2021 Barremian (125.8–121.4 Ma)United Kingdomincertae sedisunder dispute
  • Calvarius Prieto-Márquez & Sellés, 2022 Maastrichtian (72.2–66.0 Ma)Spain
  • Cedrorestes Gilpin et al., 2007 Aptian (121.4–113.2 Ma)United States
  • Dakotadon Paul, 2008 Valanginian–Barremian (137.1–121.4 Ma)United Statesunder dispute
  • Delapparentia Disputed Ruiz-Omeñaca, 2011 Barremian (125.8–121.4 Ma)Spainincertae sedis
  • Fukuisaurus Kobayashi & Azuma, 2003 Aptian (121.4–113.2 Ma)Japanunder dispute
  • Hippodraco McDonald et al., 2010 Barremian (125.8–121.4 Ma)United States
  • Hypselospinus Norman, 2010 Valanginian (137.1–132.6 Ma)United Kingdom
  • Iguanacolossus McDonald et al., 2010 Berriasian–Barremian (143.1–121.4 Ma)United States
  • Istiorachis Lockwood et al., 2025 Barremian (125.8–121.4 Ma)United Kingdom
  • Lanzhousaurus You et al., 2005 Barremian–Aptian (125.8–113.2 Ma)China
  • Lurdusaurus Taquet & Russell, 1999 Aptian (121.4–113.2 Ma)Niger
  • Magnamanus Fuentes Vidarte et al., 2016 Hauterivian–Barremian (132.6–121.4 Ma)Spain
  • Morelladon Gasulla et al., 2015 Barremian (125.8–121.4 Ma)Spain
  • Napaisaurus Ji & Zhang, 2022 Aptian (121.4–113.2 Ma)China
  • Ouranosaurus Taquet, 1976 Aptian (121.4–113.2 Ma)Niger
  • Paulodon Sancarlo et al., 2025 Barremian (125.8–121.4 Ma)Spainincertae sedisunder dispute
  • Planicoxa DiCroce & Carpenter, 2001 Aptian (121.4–113.2 Ma)United States
  • Proa McDonald et al., 2012 Albian (113.2–100.5 Ma)Spainunder dispute
  • Ratchasimasaurus Shibata et al., 2011 Aptian (121.4–113.2 Ma)Thailandunder dispute
  • Riabininohadros Lopatin & Averianov, 2020 Maastrichtian (72.2–66.0 Ma)Ukraine
  • Theiophytalia Brill & Carpenter, 2007 Aptian–Albian (121.4–100.5 Ma)United States

References

  1. Sereno, P. C. (1986). Phylogeny of the bird-hipped dinosaurs (Order Ornithischia). National Geographic Research 2(2): 234-256.

    Named Styracosterna.

    sereno1986a
  2. 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 Styracosterna.

    madzia2021a