Open Paleo

Ankylosauria

Osborn, 1923 Type genus Ankylosaurus

Its genera lived 168.2–66.0 million years ago Middle Jurassic–Late Cretaceous

Ankylosauria is a clade of herbivorous ornithischian dinosaurs that includes the great majority of the armored dinosaurs, whose bodies were sheathed in bony osteoderms much like a turtle's shell. Its members were bulky, low-slung quadrupeds carried on short, powerful limbs. The group first appeared in North Africa during the Middle Jurassic and persisted until the end of the Late Cretaceous. It was traditionally split into the Nodosauridae and the Ankylosauridae, a dichotomy that Raven and colleagues (2023) do not recover. The basal Parankylosauria, known from the latest Cretaceous of southern Gondwana, split from all other ankylosaurs before about 167 million years ago (Soto-Acuña and colleagues, 2021). Together with the plated and spiked stegosaurs, ankylosaurs make up the Thyreophora, the armored branch of ornithischians distinct from the ornithopods and marginocephalians.

Diagnosis

  1. Extensive dermal armor covering the dorsal surface and flanks
  2. Low, wide body plan with short, robust limbs
  3. Fused osteoderms on the skull forming a solid cranial shield
  4. Tail club present in Ankylosauridae (modified distal caudal vertebrae and osteoderms)
  5. Laterally projecting cervical or shoulder spines in many taxa
  6. Secondary palate present

Clades within Ankylosauria

Genera placed directly in Ankylosauria

  • Ahshislepelta Burns & Sullivan, 2011 Campanian (83.6–72.2 Ma)United Statesincertae sedisunder dispute
  • Crichtonsaurus Nomen dubium Dong, 2002 Albian–Cenomanian (113.2–93.9 Ma)Chinaincertae sedis
  • Cryptosaurus Nomen dubium Seeley, 1875 Oxfordian (161.5–154.8 Ma)United Kingdomincertae sedis
  • Heishansaurus Nomen dubium Bohlin, 1953 Barremian–Albian (125.8–100.5 Ma)Chinaincertae sedis
  • Horshamosaurus Nomen dubium Blows, 2015 Barremian (125.8–121.4 Ma)United Kingdomincertae sedis
  • Palaeoscincus Nomen dubium Leidy, 1856 Campanian (83.6–72.2 Ma)United Statesincertae sedis
  • Polacanthoides Nomen dubium Nopcsa, 1928 Berriasian–Aptian (143.1–113.2 Ma)United Kingdomincertae sedis
  • Priconodon Disputed Marsh, 1888 Aptian (121.4–113.2 Ma)United Statesincertae sedis
  • Priodontognathus Disputed Seeley, 1875 Oxfordian (161.5–154.8 Ma)United Kingdomincertae sedis
  • Sarcolestes Lydekker, 1893 Callovian (165.3–161.5 Ma)United Kingdomincertae sedis
  • Spicomellus Maidment et al., 2021 Bathonian–Callovian (168.2–161.5 Ma)Moroccoincertae sedis
  • Taohelong Yang et al., 2013 Barremian–Aptian (125.8–113.2 Ma)Chinaincertae sedisunder dispute
  • Tianchisaurus Nomen dubium Dong, 1993 Callovian (165.3–161.5 Ma)Chinaincertae sedis
  • Zhejiangosaurus Nomen dubium Lü et al., 2007 Cenomanian (100.5–93.9 Ma)Chinaincertae sedisunder dispute

References

  1. Osborn, H. F. (1923). Two Lower Cretaceous dinosaurs of Mongolia. American Museum Novitates 95: 1-10.

    Used the name Ankylosauria, as 'the armored suborder Ankylosauria', in describing Psittacosaurus; Madzia and colleagues (2021) credit the name to this paper.

    osborn1923b
  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

    Defined Ankylosauria as the largest clade containing Ankylosaurus magniventris but not Stegosaurus stenops.

    madzia2021a
  3. Raven, T. J.; Barrett, P. M.; Joyce, C. B.; Maidment, S. C. R. (2023). The phylogenetic relationships and evolutionary history of the armoured dinosaurs (Ornithischia: Thyreophora). Journal of Systematic Palaeontology 21(1): 2205433. doi:10.1080/14772019.2023.2205433

    Comprehensive recent phylogeny of the armored dinosaurs.

    raven2023a
  4. Soto-Acuña, S.; Vargas, A. O.; Kaluza, J.; Leppe, M. A.; Botelho, J. F.; Palma-Liberona, J.; Simon-Gutstein, C.; Fernández, R. A.; Ortiz, H.; Milla, V.; Aravena, B.; Manríquez, L. M. E.; Alarcón-Muñoz, J.; Pino, J. P.; Trevisan, C.; Mansilla, H.; Hinojosa, L. F.; Muñoz-Walther, V.; Rubilar-Rogers, D. (2021). Bizarre tail weaponry in a transitional ankylosaur from subantarctic Chile. Nature 600(7888): 259-263. Springer Science and Business Media LLC. doi:10.1038/s41586-021-04147-1

    Named Parankylosauria for Stegouros and its Gondwanan relatives, inferring an origin before the earliest euankylosaurs some 167 million years ago.

    soto-acuña2021a