Open Paleo

Camarasaurus

Cope, 1877 KAM-uhr-uh-SOR-uhs /ˌkæmərəˈsɔːrəs/

From Greek kamara (καμάρα) meaning 'vaulted chamber' or 'anything with an arched cover' + Greek sauros (σαῦρος) meaning 'lizard'; overall meaning 'chambered lizard', referring to the hollow pleurocoels in its cervical vertebrae.

154.8–143.1 million years ago Kimmeridgian–Tithonian, Late Jurassic
Late Jurassic stages

Camarasaurus is a genus of sauropod dinosaur that lived during the Late Jurassic in what is now the United States. Its fossils are primarily known from the Morrison Formation dating to the Kimmeridgian and Tithonian ages of the Jurassic, between 155 and 145 million years ago (mya). It was named by Edward Drinker Cope in 1877; it definitively contains three species, C. supremus, the type species, C. grandis, and C. lentus, while some researchers consider C. lewisi to be in its own genus, Cathetosaurus. The generic name means "chambered lizard", referring to the hollow chambers, known as pleurocoels, in its cervical vertebrae (Greek καμαρα [kamara] meaning 'vaulted chamber', or anything with an arched cover, and σαυρος [sauros] meaning 'lizard'). Hundreds of specimens have been excavated to date, including some nearly complete skeletons. It is among the best understood dinosaurs, with detailed studies of its anatomy, paleobiology, paleoecology, and more.

Diagnosis

  1. Dorsal vertebral centra hollow with two large internal chambers separated by a thin longitudinal median septum, communicating with exterior via a large lateral foramen below the diapophysis base.
  2. Neural arches extraordinarily elevated with neural spines set transversely to the vertebral axis; spine of anterior dorsal strongly emarginate/bifurcate.
  3. Cervical centra very elongate, exceeding proportions known in other Dinosauria and Crocodilia, with a deep linear lateral foramen running most of the centrum length.
  4. Anterior zygapophyses of neural arches separated by a deep median fissure; posterior zygapophyses united, bearing a pendant hyposphen that locks into the anterior fissure of the succeeding vertebra.
  5. Scapula relatively very large (1.517 m long) with a prominent mesoscapular process absent in Cetiosaurus; sacrum short, only four coossified centra.
  6. Caudal vertebrae amphicoelous and lacking the lateral pneumatic fossae present in dorsal centra; composed of finely spongy rather than hollow bone.

Species (4)

Camarasaurus supremus Cope, 1877

Type species

From Latin 'supremus' meaning 'supreme' or 'highest', reflecting the very large size of the type species as recognized by Cope in describing it in 1877.

Holotype
AMNH 5760 , American Museum of Natural History
Material
Cervical and twenty dorsal/lumbar vertebrae, twenty caudals, both scapulae and coracoids, half sacrum, two pairs pelvic bones, femur, tibia, one metapodial.
Horizon
upper Morrison Formation, Kimmeridgian–Tithonian, Late Jurassic , 154.8–143.1 million years ago
Locality
Cope Quarry No. 1, Colorado, United States

Synonyms

  • Caulodon junior subjective

    Cope's species C. diversidens and C. leptoganus were based on fragmentary fossils now considered referable to Camarasaurus supremus.

Camarasaurus grandis Marsh, 1877

From Latin 'grandis' meaning 'large' or 'great', referring to the animal's size.

Holotype
YPM 1901 , Yale Peabody Museum of Natural History
Material
Partial skeleton including cervical and caudal vertebrae, a femur, and metapodials.
Horizon
Morrison Formation, Kimmeridgian–Tithonian, Late Jurassic , 154.8–143.1 million years ago
Locality
Marsh Quarry No. 1, Como Bluff, Wyoming, United States
Diagnosis
  1. Neural arch of the anterior dorsal vertebrae borne on highly elevated pedicels above the centra (the arch rests directly on the centrum in C. lentus).
  2. Femoral great trochanter positioned distinctly below the femoral head and continuous with it.

Camarasaurus lentus Marsh, 1889

Holotype
YPM 1910 , Yale Peabody Museum of Natural History
Material
Partial postcranial skeleton: vertebral column C2–caudal 8, cervical rib, left scapula, right coracoid, humeri, left radius, ilia, left ischium, right pubis, left hindlimb/pes, right tibia
Horizon
Morrison Formation, Oxfordian–Kimmeridgian, Late Jurassic , 161.5–149.2 million years ago
Locality
Quarry 13, Como Bluff, Wyoming, United States Carpenter and Wilson (2008) date Quarry 13 "latest Oxfordian-earliest Kimmeridgian".
Diagnosis
  1. Smaller than C. grandis, with proportionally shorter fore- and hindlimbs.
  2. Vertebrae shorter and more massive, with smaller internal pneumatic cavities.
  3. Cervical and dorsal centra more strongly depressed (dorsoventrally compressed) than in other species.
  4. Neural arch resting directly on the centrum rather than elevated on pedicels above the articular faces (elevated in C. grandis and C. supremus).
  5. Pubic foramen open posteriorly (entirely enclosed in C. supremus and C. grandis).
  6. Axis with a depressed neural spine rising at a low angle (steeply inclined in C. supremus).

Camarasaurus lewisi (Jensen, 1988)

First named as Cathetosaurus lewisi

Honors Arnold D. Lewis, a field and laboratory preparator who trained the author.

Holotype
BYU 9047 , Earth Sciences Museum, Brigham Young University
Material
Articulated skeleton: atlas/axis plus 12 cervical vertebrae with ribs; right humerus, radius, ulna, partial manus; 12 dorsal vertebrae; 1 dorsosacral vertebra; 20 dorsal ribs; 4 sacral vertebrae and ribs co-ossified with 1 ilium; 1 pubis; both ischia; 43 anterior caudal vertebrae with articulated chevrons
Horizon
Brushy Basin Member, Morrison Formation, Kimmeridgian–Tithonian, Late Jurassic , 154.8–143.1 million years ago
Locality
Dominguez-Jones Quarry, Pit 1, Colorado, United States
Diagnosis
  1. Presacral neural spines bifid except the atlas/axis and the last dorsal, the cleft persisting from cervical 3 through dorsal 11 (ending in the mid-dorsal region in other species).
  2. Cleft in the dorsal neural spines V-shaped rather than U-shaped, extending farther posteriorly than in other species.
  3. Prominent pre-epipophyseal ridges on the cervical postzygapophyses; suprapostzygapophyseal laminae not confluent with the epipophyses.
  4. Anterior iliac processes rotated ventrally 18-20 degrees below the axis of the vertebral column.
  5. Diagonal bone-struts connecting the metapophyseal spurs of the second and third sacral neural spines to supracostal plates on the third and fourth sacral ribs.
  6. Sacrocostal plate more strongly developed than in other species, even in very aged individuals.
  7. Chevron heads with two articular surfaces of unequal orientation (anterior facet horizontal, posterior sloping about 60 degrees posteroventrally); anterior caudal chevrons about one-third longer than in C. supremus.
  8. Forelimb more slender than in C. lentus, similar to that of C. grandis.

Synonyms

  • Cathetosaurus lewisi reassigned

    Originally erected as the type species of a new genus Cathetosaurus (Jensen, 1988); McIntosh and colleagues (1996) found Cathetosaurus indistinguishable from Camarasaurus at the generic level and recombined the species as Camarasaurus lewisi.

Synonyms of the genus

Name Type Reason
Cathetosaurus possible subjective Erected by Jensen (1988) for C. lewisi and synonymized with Camarasaurus by McIntosh and colleagues (1996); some workers have since argued for its resurrection as a distinct genus.
Morosaurus junior subjective Now widely recognized as indistinguishable from Camarasaurus.
Uintasaurus junior subjective U. douglassi was found to be indistinguishable from Camarasaurus lentus and is now treated as a junior synonym.

Notable specimens

  • “E.T.”

    SMA 0002 Sauriermuseum Aathal Found 1992 by Swiss field workers of the Sauriermuseum Aathal exceptional preservation

    One of the best-known Camarasaurus skeletons, nearly every element articulated, with skin impressions showing hexagonal scales on the hindlimb and a patch of soft tissue interpreted as gums over the lower jaw and teeth. Among the oldest individuals identified, with five co-occurring pathologies.

    Tschopp et al. (2015)Wiersma & Sander (2016)

  • CM 11338

    Carnegie Museum of Natural History Found 1914 by Earl Douglass exceptional preservation

    Nearly complete and articulated juvenile skeleton unearthed at Dinosaur National Monument; one of the best sauropod specimens known to science, with nearly every element preserved in articulation, and one of only two specimens preserving a complete tail.

    Gilmore (1925)Ikejiri et al. (2005)

  • GMNH-PV 101

    Gunma Museum of Natural History Found 1992 by Jeffrie Parker and colleagues pathology

    Nearly complete articulated skeleton preserving a complete tail with pathologies in thirteen vertebrae, including spina bifida in two vertebrae, the first reported example of this condition in dinosaurs, plus osteoarthritis and five pathologically fused caudal vertebrae.

    McIntosh et al. (1996a)

References

  1. Carpenter, K.; Wilson, Y. (2008). A new species of Camptosaurus (Ornithopoda: Dinosauria) from the Morrison Formation (Upper Jurassic) of Dinosaur National Monument, Utah, and a biomechanical analysis of its forelimb. Annals of Carnegie Museum 76(4): 227-263. Carnegie Museum of Natural History. doi:10.2992/0097-4463(2008)76[227:ANSOCO]2.0.CO;2

    Dates Quarry 13 "latest Oxfordian-earliest Kimmeridgian" from regional correlations with dated horizons.

    carpenter2008a
  2. McIntosh, J. S.; Berman, D. S. (1975). Description of the palate and lower jaw of the sauropod dinosaur Diplodocus (Reptilia: Saurischia) with remarks on the nature of the skull of Apatosaurus. Journal of Paleontology 49(1): 187-199. Cambridge University Press (CUP).

    Lists YPM 1910, "type of 'Morosaurus' lentus", among the sauropods from Quarry 13.

    mcintosh1975a
  3. Cope, E. D. (1877). On a gigantic saurian from the Dakota epoch of Colorado. Paleontological Bulletin 25: 5-10. cope1877b
  4. Osborn, H. F.; Mook, C. C. (1921). Camarasaurus, Amphicoelias and other sauropods of Cope. Memoirs of the American Museum of Natural History, New Series 3(3): 249-387.

    Comprehensive iconographic monograph redescribing all of Cope's Canyon City sauropod material at the AMNH; the primary osteological reference for Camarasaurus supremus.

    osborn1921a
  5. Gilmore, C. W. (1925). A nearly complete articulated skeleton of Camarasaurus, a saurischian dinosaur from the Dinosaur National Monument. Memoirs of the Carnegie Museum 10: 347-384. doi:10.5962/p.217807 gilmore1925a
  6. McIntosh, J. S.; Miles, C. A.; Cloward, K. C.; Parker, J. R. (1996). A new nearly complete skeleton of Camarasaurus. Bulletin of Gunma Museum of Natural History 1: 1-87. mcintosh1996a
  7. Ikejiri, T.; Tidwell, V.; Trexler, D. L. (2005). New adult specimens of Camarasaurus lentus highlight ontogenetic variation within the species. Thunder-Lizards: The Sauropodomorph Dinosaurs 154-179. Indiana University Press, Bloomington. ikejiri2005a
  8. Tschopp, E.; Wings, O.; Frauenfelder, T.; Brinkmann, W. (2015). Articulated bone sets of manus and pedes of Camarasaurus (Sauropoda, Dinosauria). Palaeontologia Electronica. doi:10.26879/559 tschopp2015b
  9. 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 91(1): 145-161. doi:10.1007/s12542-016-0332-6 wiersma2016a
  10. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Sauropods. Princeton University Press.

    Source of the hip height estimate.

    jones2026b
  11. Marsh, O. C. (1877). Notice of new dinosaurian reptiles from the Jurassic formation. American Journal of Science s3-14(84): 514-516. American Journal of Science (AJS). doi:10.2475/ajs.s3-14.84.514

    Erects the basionym Apatosaurus grandis, later recombined as Camarasaurus grandis.

    marsh1877c
  12. Marsh, O. C. (1889). Notice of new American Dinosauria. American Journal of Science 37(220): 331-336. doi:10.2475/ajs.s3-37.220.331

    Erects the basionym Morosaurus lentus, later recombined as Camarasaurus lentus.

    marsh1889b
  13. 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. Brigham Young University.

    Original description of the species, as Cathetosaurus lewisi.

    jensen1988a
  14. McIntosh, J. S.; Miller, W. E.; Stadtman, K. L.; Gillette, D. D. (1996). The osteology of Camarasaurus lewisi (Jensen, 1988). Brigham Young University Geology Studies 41: 73-115. Brigham Young University.

    Redescribes the holotype (BYU 9047, misprinted as BYU 9740 in the original description) and synonymizes Cathetosaurus with Camarasaurus, providing a revised diagnosis of Camarasaurus lewisi.

    mcintosh1996b