Open Paleo

Neornithischia

Cooper, 1985

Its genera lived 184.2–66.0 million years ago Early Jurassic–Late Cretaceous

Neornithischia ("new ornithischians") is a clade of ornithischian dinosaurs and the sister group of the armored Thyreophora within the larger clade Genasauria. It brings together a variety of basal, small-bodied early-diverging forms historically lumped together as "hypsilophodonts" — including the thescelosaurids — with the more derived Cerapoda, which in turn splits into the bird-footed Ornithopoda and the Marginocephalia, the latter comprising the dome-headed pachycephalosaurs and the horned ceratopsians. Members are set apart by a thicker layer of asymmetrical enamel on the inner face of their lower teeth, which wore unevenly during chewing to develop sharp ridges that let them break down tougher plant food than other dinosaurs. The earliest neornithischians were small, gracile, cursorial bipeds, but the clade went on to encompass some of the most successful herbivore radiations of the Mesozoic, among them the duck-billed, dome-headed, and horned dinosaurs.

Diagnosis

  1. Tab-shaped (subrectangular) obturator process on the ischium
  2. Articulation between the sacral ribs and the ischiadic peduncle of the ilium
  3. Cheek-tooth crowns low and triangular with a well-developed primary ridge
  4. Premaxillary dentition reduced and restricted to the anterior premaxilla

Clades within Neornithischia

Genera placed directly in Neornithischia

  • Agilisaurus Peng, 1992 Bajocian–Oxfordian (170.9–154.8 Ma)China
  • Enigmacursor Maidment & Barrett, 2025 Kimmeridgian–Tithonian (154.8–143.1 Ma)United States
  • Hexinlusaurus Barrett et al., 2005 Bajocian–Oxfordian (170.9–154.8 Ma)China
  • Kulindadromeus Godefroit et al., 2014 Bathonian (168.2–165.3 Ma)Russia
  • Laosaurus Nomen dubium Marsh, 1878 Kimmeridgian–Tithonian (154.8–143.1 Ma)United Statesincertae sedisunder dispute
  • Minimocursor Manitkoon et al., 2023 Tithonian–Berriasian (149.2–137.1 Ma)Thailand
  • Nanosaurus Disputed Marsh, 1877 Kimmeridgian–Tithonian (154.8–143.1 Ma)United Statesincertae sedis
  • Phyllodon Nomen dubium Thulborn, 1973 Kimmeridgian (154.8–149.2 Ma)Portugalincertae sedisunder dispute
  • Pulaosaurus Yang et al., 2025 Callovian–Oxfordian (165.3–154.8 Ma)China
  • Sanxiasaurus Li et al., 2021 Toarcian–Aalenian (184.2–170.9 Ma)China
  • Yandusaurus He, 1979 Bajocian–Oxfordian (170.9–154.8 Ma)China
  • Yueosaurus Zheng et al., 2012 Albian–Cenomanian (113.2–93.9 Ma)Chinaincertae sedisunder dispute

References

  1. Cooper, M. R. (1985). A revision of the ornithischian dinosaur Kangnasaurus coetzeei Haughton, with a classification of the Ornithischia. Annals of the South African Museum 95: 281-317.

    Erected Neornithischia.

    cooper1985a
  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 Neornithischia.

    madzia2021a