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Thyreophora

Nopcsa, 1915

Its genera lived 201.4–66.0 million years ago Early Jurassic–Late Cretaceous

Thyreophora, meaning "shield bearers," is a clade of armored ornithischian dinosaurs. It contains two major subgroups, the plated stegosaurs and the heavily armored ankylosaurs, together with a grade of early-diverging forms such as Scutellosaurus, Emausaurus, and Scelidosaurus. Its members are defined by body armor arranged in longitudinal rows along the back and flanks: primitive forms bore simple low keeled scutes, while more derived members developed elaborate spikes and plates. Thyreophorans first appeared in the Early Jurassic and persisted until the end of the Cretaceous. The earliest species were small and at least partly bipedal, but the group trended toward a robust, low-slung body plan, with the large stegosaurs and ankylosaurs becoming obligate quadrupeds whose forelimbs were much shorter than their hindlimbs.

Diagnosis

  1. Parasagittal rows of keeled dermal osteoderms along the dorsal surface
  2. Low, transversely broad jugal with a horizontally expanded anterior process
  3. Postorbital region of the skull roof thickened and rugose
  4. Robust, low-slung body plan trending toward obligate quadrupedality
  5. Simple, low-crowned, leaf-shaped cheek teeth

Clades within Thyreophora

Genera placed directly in Thyreophora

  • Bienosaurus Nomen dubium Dong, 2001 Hettangian–Sinemurian (201.4–192.9 Ma)Chinaincertae sedisunder dispute
  • Emausaurus Haubold, 1990 Toarcian (184.2–174.7 Ma)Germany
  • Jakapil Riguetti et al., 2022 Cenomanian (100.5–93.9 Ma)Argentinaunder dispute
  • Minmi Disputed Molnar, 1980 Aptian (121.4–113.2 Ma)Australiaincertae sedis
  • Regnosaurus Nomen dubium Mantell, 1848 Valanginian (137.1–132.6 Ma)United Kingdomincertae sedisunder dispute
  • Scelidosaurus Owen, 1859 Sinemurian (199.5–192.9 Ma)United Kingdomunder dispute
  • Scutellosaurus Colbert, 1981 Sinemurian–Pliensbachian (199.5–184.2 Ma)United States
  • Stegosaurides Nomen dubium Bohlin, 1953 Barremian–Albian (125.8–100.5 Ma)Chinaincertae sedisunder dispute
  • Tatisaurus Nomen dubium Simmons & Nash, 1965 Sinemurian (199.5–192.9 Ma)Chinaincertae sedisunder dispute
  • Yuxisaurus Yao et al., 2022 Pliensbachian (192.9–184.2 Ma)China

References

  1. Nopcsa, B. F. (1915). Die Dinosaurier der siebenbürgischen Landesteile Ungarns [The Dinosaurs of the Transylvanian Territories of Hungary]. Mitteilungen aus dem Jahrbuche der Königlich Ungarischen Geologischen Reichsanstalt 23: 1-26.

    Erected Thyreophora.

    nopcsa1915a
  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 Thyreophora.

    madzia2021a