Open Paleo

Thyreosaurus

Zafaty et al., 2024 TIE-ree-o-SOR-us

From Greek 'thyreos' meaning 'shield' (a large oblong shield) and 'sauros' meaning 'lizard', referring to the distinctive shield-like dermal armor of the animal.

168.2–161.5 million years ago Bathonian–Callovian, Middle Jurassic
Middle Jurassic stages

Thyreosaurus is an extinct genus of stegosaurian dinosaur from the Middle Jurassic El Mers III Formation of Morocco. The genus contains a single species, Thyreosaurus atlasicus, known from a partial disarticulated skeleton consisting of several dorsal vertebrae, ribs, a limb bone, and dermal bones. Thyreosaurus is characterized by a unique dermal armor with an asymmetrical texture, indicating that it may have been recumbent. Alongside Adratiklit, Thyreosaurus increases the diversity of unique stegosaurs occurring in the Middle Jurassic of Africa.

Diagnosis

  1. Thick osteoderms (up to 4 cm) with asymmetrical texture: one side with small pits and fiber bundles, other with cross-hatched pattern
  2. Dermal elements arranged in recumbent position rather than erect, based on fiber bundle orientation
  3. Dorsal centra wider than long, smaller in overall dimensions relative to neural arch than Dacentrurus
  4. Prezygapophyses with horizontal orientation in lateral view and continuous prezygodiapophyseal lamina lacking deep notch
  5. Prominent ventral notch between postzygapophyses and ventral keel on all dorsal centra

Species

Thyreosaurus atlasicus Zafaty et al., 2024

Type species

Named for the Atlas Mountains of Morocco, where the holotype was discovered near Boulemane in the Middle Atlas.

Holotype
HIIUC BN00 , Hassan II University of Casablanca
Material
Partial postcranial skeleton including 9 dorsal vertebrae, 21 dorsal ribs, and 6 dermal elements
Horizon
El Mers III Formation, Bathonian–Callovian, Middle Jurassic , 168.2–161.5 million years ago
Locality
Boulahfa North, Boulemane, Morocco

References

  1. Zafaty, O.; Oukassou, M.; Riguetti, F.; Company, J.; Bendrioua, S.; Tabuce, R.; Charrière, A.; Pereda-Suberbiola, X. (2024). A new stegosaurian dinosaur (Ornithischia: Thyreophora) with a remarkable dermal armour from the Middle Jurassic of North Africa. Gondwana Research 131: 344-362. Elsevier BV. doi:10.1016/j.gr.2024.03.009 zafaty2024a
  2. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Ornithischians. Princeton University Press.

    Source of the appearance features.

    jones2026a