Open Paleo

Stegouros

Soto-Acuña et al., 2021 steh-GOO-ross /ˌstɛɡəˈjʊərɒs/

From Greek 'stegos' meaning 'roof' and 'oura' meaning 'tail'; meaning 'roofed tail', referring to the roof-like covering of osteoderms over the tail.

83.6–66.0 million years ago Campanian–Maastrichtian, Late Cretaceous
Late Cretaceous stages

Stegouros is an extinct genus of ankylosaurian dinosaurs from the Late Cretaceous Dorotea Formation of southern Chile. The genus contains a single species, Stegouros elengassen, known from a semi-articulated, near-complete skeleton. Stegouros is a member of the Parankylosauria, a clade of small Gondwanan armored dinosaurs. It is characterized by its small body size and distinct arrangement of fused osteoderms forming a macuahuitl-like tail weapon.

Diagnosis

  1. Short tail with no more than 26 vertebrae (lowest among armored dinosaurs)
  2. Seven pairs of large laterally-projecting osteoderms covering distal tail
  3. Distalmost five osteoderms fused into flat composite unit forming frond-like structure
  4. Medially bowed dentary tooth rows with 14 alveoli
  5. Strongly medially inset maxillary tooth rows
  6. Maxilla with medial process forming secondary palate

Species

Stegouros elengassen Soto-Acuña et al., 2021

Type species

Named for 'elengassen', an armored creature in the mythology of the Aónik'enk, the indigenous inhabitants of the region of southern Chile where the holotype was discovered.

Holotype
CPAP-3165 , Instituto Antártico Chileno
Material
Mostly complete skeleton with largely articulated posterior half (tail, sacrum, pelvis, hindlimbs), disarticulated anterior skeleton including vertebrae, sternal plates, coracoids, forelimbs, osteoderms, cranial bones.
Horizon
lower Dorotea Formation, Campanian–Maastrichtian, Late Cretaceous , 83.6–66.0 million years ago
Locality
SP17, Magellan and the Chilean Antarctic, Chile

References

  1. 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 soto-acuña2021a
  2. Paul, G. S. (2024). The Princeton Field Guide to Dinosaurs (3rd ed.). Princeton University Press.

    Source of the mass estimate.

    paul2024a
  3. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Ornithischians. Princeton University Press.

    Source of the hip height estimate, and the appearance features.

    jones2026a