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Temporal range: Late Jurassic, 155–145 Ma
Cathetosaurus skeleton 1.jpg
Referred specimen SMA 002
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Clade: Dinosauria
Order: Saurischia
Suborder: Sauropodomorpha
Clade: Neosauropoda
Clade: Macronaria
Clade: Camarasauridae
Genus: Cathetosaurus
Jensen, 1988
Type species
Cathetosaurus lewisi
Jensen, 1988

Cathetosaurus is a dinosaur sauropod genus that contains one species: Cathetosaurus lewisi[1] that was thought to be within the Camarasaurus genus. The holotype specimen was originally described by James Jensen and is now in the Brigham Young University collection.


Sacrum of holotype BYU 9047

Cathetosaurus is supposedly different from other species due to the bifurcation (split) of its neck vertebrae starting at a different point in the neck, and bony tendons present in the hip region. However, no other Camarasaurus specimens are well preserved enough to be sure the supposedly distinct neck vertebrae are really distinct, and bony hip tendons are also known in large, mature specimens of C. lentus and C. supremus, indicating that this difference may be a feature that changed with age.[2]

Soft tissue from the mouth region of SMA 002 made researchers propose in 2016 that the tooth crowns were covered by gingival tissue, and perhaps a keratinous beak.[3]

The diagnostic characters for Cathetosaurus are: the pelvis is rotated anteriorly, such that the pubis projects posteroventrally, and the ischium projects posteriorly, lateroventrally projecting spurs in the neural spines of the last dorsals; posterior cervical and anterior dorsal diapophyses bearing an anterior projection lateral to the prezygapophysis. Frontals with anterior midline projection into the nasals; trapezoidal supraoccipital (more expanded dorsally than ventrally), lateral spur on the dorsal part of the lacrimal, iv) fenestrated pterygoid; the large pineal foramen between the frontals.[4]


The holotype specimen of Cathetosaurus lewisi is contemporary with the middle of the C. grandis age range. This species was originally named as Cathetosaurus lewisi and later synonymized with Camarasaurus. More recent research has split the two genera again, based on the recognition of a second specimen.[4]


  1. ^ Jensen, J. A. (1988). "A fourth new sauropod dinosaur from the Upper Jurassic of the Colorado Plateau and sauropod bipedalism". Great Basin Naturalist. 48 (2): 121–145. 
  2. ^ Ikejiri, T. (2005). Distribution and biochronology of Camarasaurus (Dinosauria, Sauropoda) from the Jurassic Morrison Formation of the Rocky Mountain Region. In New Mexico Geological Society, 56th Field Conference Guidebook, Geology of the Chama Basin (pp. 367-379).
  3. ^ Wiersma, K.; Sander, P. M. (2016). "The dentition of a well-preserved specimen of Camarasaurus sp.: implications for function, tooth replacement, soft part reconstruction, and food intake". PalZ. doi:10.1007/s12542-016-0332-6. 
  4. ^ a b Mateus, O., & Tschopp E. (2013). Cathetosaurus as a valid sauropod genus and comparisons with Camarasaurus. Journal of Vertebrate Paleontology, Program and Abstracts, 2013. 173.