Open Paleo

Brontosaurus

Marsh, 1879 BRON-tuh-SOR-uhs /ˌbrɒntəˈsɔːrəs/

From Greek bronte (βροντή) meaning 'thunder' and Greek sauros (σαῦρος) meaning 'lizard'. Full meaning: 'thunder lizard'.

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

Brontosaurus is a genus of herbivorous sauropod dinosaur that lived in present-day United States during the Late Jurassic period. It was described by American paleontologist Othniel Charles Marsh in 1879, the type species being dubbed B. excelsus, based on a partial skeleton lacking a skull found in Como Bluff, Wyoming. In subsequent years, two more species of Brontosaurus were named: B. parvus in 1902 and B. yahnahpin in 1994. Brontosaurus lived about 156 to 146 million years ago (mya) during the Kimmeridgian and Tithonian ages in the Morrison Formation of what is now Utah and Wyoming. For decades, the animal was thought to have been a taxonomic synonym of its close relative Apatosaurus, but a 2015 study by Emmanuel Tschopp and colleagues found it to be distinct. It has seen widespread representation in popular culture, being the archetypal "long-necked" dinosaur in general media.

Under dispute

Brontosaurus was resurrected as a genus distinct from Apatosaurus on the basis of a specimen-level phylogenetic analysis (Tschopp and colleagues, 2015), which is followed. The separation is not universally accepted, and some workers continue to regard Brontosaurus as a junior synonym of Apatosaurus.

Diagnosis

  1. Base of the posterior dorsal neural spines longer than wide
  2. Scapula excavated in the area posterior to the acromial ridge and the distal blade
  3. Acromial edge of the scapular blade bearing a rounded expansion at its distal end
  4. Astragalus with a proximodistal length to transverse breadth ratio of 0.55 or greater

Species

Brontosaurus excelsus Marsh, 1879

Type species

From Latin 'excelsus' meaning 'lofty' or 'elevated', likely referring to the great stature of the animal.

Holotype
YPM 1980 , Yale Peabody Museum of Natural History
Material
Partial remains including sacrum, ilium, lumbar vertebrae, and caudal vertebrae.
Horizon
Brushy Basin Member, Morrison Formation, Kimmeridgian–Tithonian, Late Jurassic , 154.8–143.1 million years ago
Locality
Reed's Quarry 10, Como Bluff, Wyoming, United States

Synonyms of the genus

Name Type Reason
Elosaurus junior subjective Originally described as Elosaurus parvus by Peterson and Gilmore (1902); reassigned to Apatosaurus in 1994 and ultimately to Brontosaurus parvus by Tschopp and colleagues (2015).
Eobrontosaurus junior subjective Erected by Bakker (1998) for material originally referred to Apatosaurus yahnahpin; now generally placed in Brontosaurus yahnahpin.

Notable specimens

  • UW 15556

    University of Wyoming Geological Museum Found 1901 by William Harlow Reed most complete

    A very well-preserved adult postcranial skeleton bearing many cervical and caudal vertebrae; the most complete definite specimen of the species. Found intermingled with a juvenile skeleton (CM 566) during a Carnegie Museum expedition.

    Tschopp et al. (2015)

  • AMNH 460

    American Museum of Natural History historic

    Principal specimen of the first-ever mounted sauropod skeleton, unveiled by the AMNH in 1905 as Brontosaurus excelsus, a composite incorporating bones from AMNH 592, 222, and 339 plus a sculpted conjectural skull.

    Norell et al. (1995)

References

  1. Marsh, O. C. (1879). Notice of new Jurassic reptiles. American Journal of Science s3-18(108): 501-505. American Journal of Science (AJS). doi:10.2475/ajs.s3-18.108.501 marsh1879a
  2. Norell, M. A.; Gaffney, E. S.; Dingus, L. (1995). Discovering Dinosaurs in the American Museum of Natural History. Alfred A. Knopf. norell1995a
  3. Tschopp, E.; Mateus, O.; Benson, R. B. J. (2015). A specimen-level phylogenetic analysis and taxonomic revision of Diplodocidae (Dinosauria, Sauropoda). PeerJ 3: e857. PeerJ. doi:10.7717/peerj.857

    Specimen-level revision that resurrected Brontosaurus as a genus distinct from Apatosaurus.

    tschopp2015a
  4. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Sauropods. Princeton University Press.

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

    jones2026b
  5. Bakker, R. T. (1998). Dinosaur mid-life crisis: the Jurassic-Cretaceous transition in Wyoming and Colorado. New Mexico Museum of Natural History and Science Bulletin 14: 67-77. New Mexico Museum of Natural History and Science.

    Erected Eobrontosaurus for material referred to Apatosaurus yahnahpin.

    bakker1998a
  6. Peterson, O. A.; Gilmore, C. W. (1902). Elosaurus parvus: a new genus and species of the Sauropoda. Annals of the Carnegie Museum 1: 490-499. doi:10.5962/p.78087 peterson1902a