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Chebsaurus

Mahammed et al., 2005 cheb-SOR-us

From colloquial Arabic 'cheb' (شاب) meaning 'young man', referring to the juvenile nature of the fossils found, combined with Greek 'sauros' meaning 'lizard'.

165.3–149.2 million years ago Callovian–Kimmeridgian, Middle Jurassic–Late Jurassic
Middle Jurassic and Late Jurassic stages

Chebsaurus is a genus of sauropod dinosaur, specifically a eusauropod. It lived in present-day Algeria, in the Aïssa Formation. The type species, C. algeriensis, was named in 2005 by Mahammed and colleagues and is the most complete Algerian sauropod known. It was around 8 to 9 meters (26 to 30 ft) long.

Under dispute

Chebsaurus was erected within Cetiosauridae (Mahammed and colleagues, 2005), a referral its describers presented as untested pending a phylogenetic analysis. That analysis (Läng and Mahammed, 2010) recovered Cetiosauridae sensu Bonaparte (1986) as paraphyletic and placed Chebsaurus in an unresolved polytomy with Lapparentosaurus, Ferganasaurus and Cetiosaurus, referring the genus no further than Eusauropoda. Subsequent treatments follow that reading, listing it as a non-neosauropod eusauropod (Mannion and colleagues, 2019). No numerical analysis has recovered it within a monophyletic Cetiosauridae.

Diagnosis

  1. Slender surangular
  2. Short and robust basioccipital tubera diverging from each other at a 60° angle, with elliptical anteroventral facets whose long axis is oriented anterodorsally
  3. Pneumatic fossae of the dorsal vertebrae positioned on the anterior two-thirds of the lateral surface
  4. Ventral surface of the anterior caudal vertebrae slightly narrowed transversally
  5. Slender limbs and girdles, the ratio between the midshaft diameter of the ulna and its length being 0.07
  6. Absence of a coracoid notch on the ventral side of the coracoid

Species

Chebsaurus algeriensis Mahammed et al., 2005

Type species

Named for Algeria, the country where the fossils were discovered.

Holotype
D001-01, D001-02, D001-03, D001-04, D001-05, D001-06, D001-07, D001-08, D001-09, D001-10, D001-11, D001-12, D001-13, D001-14, D001-15, D001-16, D001-17, D001-18, D001-19, D001-20, D001-21, D001-22, D001-23, D001-24, D001-25, D001-26, D001-27, D001-28, D001-29, D001-30, D001-31, D001-32, D001-33, D001-34, D001-35, D001-36, D001-37, D001-38, D001-39, D001-40, D001-41, D001-42, D001-43, D001-44, D001-45, D001-46, D001-47, D001-48, D001-49, D001-50, D001-51, D001-52, D001-53, D001-54, D001-55, D001-56, D001-57, D001-58, D001-59, D001-60, D001-61, D001-62, D001-63, D001-64, D001-65, D001-66, D001-67, D001-68, D001-69, D001-70, D001-71, D001-72, D001-73, D001-74, D001-75, D001-76, D001-77, D001-78 , Research and Development Center of Sonatrach
Material
Partial juvenile skeleton with vertebrae, incomplete girdle and limb bones, and cranial material including the basicranium, surangular, and teeth.
Horizon
Aïssa Formation, Callovian–Kimmeridgian, Middle Jurassic–Late Jurassic , 165.3–149.2 million years ago
Locality
Rouis El Djir, Naama, Algeria Kacemi and colleagues (2026) place the bones in the informal Member of the Rouis el Djir Alternations (MI), the lower member of the formation, in unit E3 at levels 73 to 78: "These same bioturbated greenish clays yielded the bones of Chebsaurus". The Djara Formation lies beneath the Aïssa in the same syncline.

References

  1. Mahammed, F.; Läng, É.; Mami, L.; Mekahli, L.; Benhamou, M.; Bouterfa, B.; Kacemi, A.; Chérief, S. A.; Chaouati, H.; Taquet, P. (2005). The 'Giant of Ksour', a Middle Jurassic sauropod dinosaur from Algeria. Comptes Rendus Palevol 4(8): 707-714. Museum National D'Histoire Naturelle. doi:10.1016/j.crpv.2005.07.001 mahammed2005a
  2. Läng, É.; Mahammed, F. (2010). New anatomical data and phylogenetic relationships of Chebsaurus algeriensis (Dinosauria, Sauropoda) from the Middle Jurassic of Algeria. Historical Biology 22(1-3): 142-164. Taylor & Francis. doi:10.1080/08912960903515570

    New cranial and postcranial material from two juvenile individuals, with an emended diagnosis and a phylogenetic analysis leaving the genus in an unresolved non-neosauropod eusauropod polytomy.

    läng2010a
  3. Mannion, P. D.; Upchurch, P.; Schwarz, D.; Wings, O. (2019). Taxonomic affinities of the putative titanosaurs from the Late Jurassic Tendaguru Formation of Tanzania: phylogenetic and biogeographic implications for eusauropod dinosaur evolution. Zoological Journal of the Linnean Society 185(3): 784-909. Oxford University Press (OUP). doi:10.1093/zoolinnean/zly068

    Lists Chebsaurus among the non-neosauropod eusauropods of the Middle Jurassic of Africa.

    mannion2019a
  4. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Sauropods. Princeton University Press.

    Source of the mass and hip height estimates.

    jones2026b
  5. Bonaparte, J. F. (1986). Les Dinosaures (Carnosaures, Allosaurides, Sauropodes, Cetiosaurides) du Jurassique moyen de Cerro Cóndor (Chubut, Argentine) [The Dinosaurs (Carnosaurs, Allosaurids, Sauropods, Cetiosaurids) of the Middle Jurassic of Cerro Cóndor (Chubut, Argentina)]. Annales de paléontologie 72(4): 325-386. bonaparte1986b
  6. Kacemi, A.; Benhamou, M.; Boucif, A.; Benramdane, H.; Hebib, H. (2026). Évolution des milieux de dépôt et traces des dinosauriens du Jurassique supérieur dans les Monts des Ksour (Atlas saharien, Algérie) [Evolution of depositional environments and dinosaur tracks of the Upper Jurassic in the Ksour Mountains (Saharan Atlas, Algeria)]. Estudios Geológicos 82(2): e1154. doi:10.3989/egeol.45894.1154

    Places the bones in the Aïssa Formation and dates their dinosaur biotope "Callovian-Kimmeridgian", the bracket the species takes.

    kacemi2026a
  7. Benddine, A.; Benaouda, S. (2022). Lithostratigraphie et paléo environnement de la « Formation de Aïssa », coupes de Rouis El Djir et Djebel Larouia, Sillon pré-atlasique – Monts des Ksour (Atlas saharien) [Lithostratigraphy and paleoenvironment of the 'Aïssa Formation', Rouis El Djir and Djebel Larouia sections, pre-Atlas trough, Ksour Mountains (Saharan Atlas)]. Masters thesis, Université Abou Bekr Belkaïd, Tlemcen. https://dspace.univ-tlemcen.dz/handle/112/19392

    Supervised by Kacemi; puts the find at the same level and holds that "the Kimmeridgian age is much more probable".

    benddine2022a