DinoDex
Long, slender sauropod with a whip-like tail and a row of low spines along its back, in side view
Scientific reconstruction of Diplodocus carnegii.Image credit: Fred Wierum, CC BY-SA 4.0, via Wikimedia Commons (unmodified except resizing)CC BY-SA 4.0 (unmodified)Source (opens in a new tab)

Diplodocus carnegii

Pronounced dih-PLOD-oh-kus kar-NEG-ee-eye

Sauropoda · Diplodocidae

A very long, slender sauropod from the Late Jurassic Morrison Formation of Wyoming, with a whip-like tail. Its skeleton, "Dippy", was cast and sent to museums around the world, making it one of the most seen dinosaurs anywhere.

  • Giant
  • Long necked
  • Quadrupedal
  • Famous specimen
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Period
Jurassic· Kimmeridgian
Diet
Herbivore
Length
24–26 m
Mass
12,000–14,800 kg
Location
Wyoming, United States, Colorado

Quick answers

How big was Diplodocus carnegii?
Diplodocus carnegii was about 24–26 m long. It stood about 3–3.4 m tall at the hips. It weighed about 12–14.8 t. (Wikipedia: Diplodocus 2026; Paul 2016)
When did Diplodocus carnegii live?
Diplodocus carnegii lived during the Late Jurassic, about 154.8–143.1 million years ago. (Paleobiology Database: Diplodocus occurrences 2026)
Where have Diplodocus carnegii fossils been found?
Fossils of Diplodocus carnegii have been found in Morrison Formation (Colorado) and United States. (Marsh 1878; Hatcher 1901)
What did Diplodocus carnegii eat?
Diplodocus carnegii was a herbivore. (Marsh 1878; Hatcher 1901)
Who named Diplodocus carnegii, and when?
Diplodocus carnegii was described by John Bell Hatcher in 1901. (Hatcher 1901; Tschopp et al. 2015)

On this page

dih-PLOD-oh-kus kar-NEG-ee-eye

Period
Jurassic154.8–143.1 Ma
Diet
Herbivore
Length
24–26 m
Mass
12–14.8 t
Location
United States
Classification
Sauropoda · Diplodocidae
Described
1901, John Bell Hatcher

Overview

Diplodocus carnegii lived in western North America in the Late Jurassic. John Bell Hatcher named it in 1901 from a skeleton (CM 84) dug up at Sheep Creek, Wyoming, by a Carnegie Museum crew, and named it after the museum's patron, Andrew Carnegie. Carnegie gave casts of the mounted skeleton, nicknamed "Dippy", to museums in Europe and Latin America.

Diplodocus was long and relatively light for a sauropod, with a horizontal neck, peg-like teeth at the front of the jaws and a tail of about 80 vertebrae ending in a thin whip. The genus is named for the double-beamed chevron bones under its tail.

The first species, D. longus (Marsh 1878), is based on poor material, and a proposal to make D. carnegii the type species was rejected by the ICZN in 2018. Whether the tail could crack like a bullwhip at supersonic speed is debated: a 1997 model said yes, a 2022 model found the tip reached only about 30 m/s.

Name meaning

From Greek diploos ("double") and dokos ("beam"), for the double chevron bones under the tail (Marsh 1878); carnegii honours Andrew Carnegie (Hatcher 1901).

Biology & evidence

What scientists think about how this animal lived, and how strong the evidence for each idea is.

Skin & covering

  • Diplodocus had a row of pointed spines along its back.

    Evidence level: Hypothesis

    Spines were found with diplodocid skin impressions, but not with a Diplodocus carnegii skeleton, and their position on the body is inferred.

    Evidence for / against · 1
    Evidence for

    • Skin impression · Diplodocid dermal spines

      Skin impressions from a diplodocid quarry in Wyoming with narrow, pointed keratinous spines, reconstructed as a row along the midline.

Biomechanics

  • Diplodocus could crack its tail like a whip at supersonic speed.

    Evidence level: Disputed

    A 1997 model said the tail tip could break the sound barrier. A 2022 model including soft tissue found the tip reached only about 30 m/s and that tissues would fail at supersonic speed.

    Evidence for / against · 2
    Evidence for

    • Biomechanical model · Supersonic diplodocid tail model

      A computer model of the Apatosaurus louisae tail reaching supersonic speed at the tip, like a bullwhip.

    Evidence against

    • Biomechanical model · Diplodocid tail multibody model

      A multibody model with soft-tissue strength limits: the tail tip reaches about 30 m/s, far below the speed of sound.

Other

  • Diplodocus longus, not D. carnegii, is the type species of Diplodocus.

    Evidence level: Direct evidence

    This is a naming decision, not a biological finding: in 2018 the ICZN kept the original type species even though its fossils are poor.

    Evidence for / against · 1
    Evidence for

    • Other · ICZN Opinion 2425 on the type species of Diplodocus

      The Commission declined to replace D. longus with D. carnegii as the type species.

Size

Length
24–26 m

(85.3 ft)

Based on CM 84

Height
3.2 mpublished range 3–3.4 m

(10.5 ft)

Based on CM 84 (holotype, femur 1.54 m)

Mass
12,000–14,800 kg

Based on CM 84

Diplodocus carnegii was about 26 m (85.3 ft) long, roughly 14.4 times the height of a 1.8 m adult human.

Timeline

Lived from about 154.8 to 143.1 million years ago (Ma), within the Mesozoic era (252–66 Ma).

Periods: Kimmeridgian (154.8–149.2 Ma), Tithonian (149.2–145 Ma), Late Jurassic (161.5–145 Ma)

First and last appearance bounds of D. carnegii in PBDB (Kimmeridgian-Tithonian, PBDB time scale).

Location

Formations

Map data: Natural Earth (public domain). Modern positions, not where the continents were then.

These are the places where fossils have been found, not the full area where the animal lived.

Ecosystem

Lived in: Morrison

156–147 million years ago · floodplain, river system, open woodland, lake

A vast, seasonally dry floodplain crossed by rivers in the western interior of North America in the Late Jurassic, with a wet and a dry season, conifer and fern vegetation along the water and giant sauropods in abundance.

Same ecosystem

Allosaurus fragilis

Jurassic· KimmeridgianCarnivore

Same ecosystem

Stegosaurus stenops

Jurassic· KimmeridgianHerbivore

Same ecosystem

Brachiosaurus altithorax

Jurassic· KimmeridgianHerbivore

Same ecosystem

Brontosaurus excelsus

Jurassic· KimmeridgianHerbivore

Same ecosystem

Apatosaurus ajax

Jurassic· KimmeridgianHerbivore

Same ecosystem

Ceratosaurus nasicornis

Jurassic· KimmeridgianCarnivore

Classification

  1. cladeDinosauria
  2. cladeSaurischia
  3. cladeSauropodomorpha
  4. cladeSauropoda
  5. superfamilyDiplodocoidea
  6. familyDiplodocidae
  7. subfamilyDiplodocinae
  8. genusDiplodocus
  9. speciesDiplodocus carnegii

Taxonomic status: Valid

Fossil record

The Diplodocus carnegii holotype (CM 84, with CM 94 and CM 307), mounted at the Carnegie Museum of Natural History, Pittsburgh.Image credit: James St. John, CC BY 2.0, via Wikimedia Commons, Carnegie Museum of Natural HistoryCC BY 2.0Source (opens in a new tab)
Specimens
Catalog numberStatusInstitutionFound
CM 84 “Dippy”HolotypeCarnegie Museum of Natural History (CM)1899
CM 94ParatypeCarnegie Museum of Natural History (CM)—

What has been found

Holotype: CM 84 “Dippy”

  • Preserved
  • Partial
  • Reconstructed
  • Unknown / not recorded
Region by region (table)
Skeleton regions of Holotype: CM 84 “Dippy”
RegionState
SkullUnknown / not recorded
MandibleUnknown / not recorded
TeethUnknown / not recorded
Cervical vertebraePreserved
Dorsal vertebraePartial
SacrumUnknown / not recorded
Caudal vertebraePartial
RibsUnknown / not recorded
GastraliaUnknown / not recorded
Scapula / shoulder girdleUnknown / not recorded
HumerusUnknown / not recorded
Forearm (radius / ulna)Unknown / not recorded
Hand (manus)Unknown / not recorded
PelvisUnknown / not recorded
FemurUnknown / not recorded
Tibia / fibulaUnknown / not recorded
Foot (pes)Unknown / not recorded
Multiview skeletal reconstruction of Diplodocus carnegii, scaled as CM 84 'Dippy', with a human for scale.Image credit: Gunnar Bivens, CC BY 3.0, via Wikimedia CommonsCC BY 3.0Source (opens in a new tab)

Gallery

Historical reconstruction: Charles R. Knight's 1919 illustration with Brontosaurus wading in water and Diplodocus on land, reflecting the outdated view of swamp-bound sauropods.Image credit: Charles R. Knight, Public domain, via Wikimedia CommonsPublic domain

All specimens

Discovery

Year described
1901
Described by
John Bell Hatcher
Type specimen
CM 84
The New York Journal and Advertiser of 11 December 1898 announcing the find that led Andrew Carnegie to fund the Diplodocus carnegii excavations.Image credit: New York Journal and Advertiser (via Library of Congress), Public domain, via Wikimedia CommonsPublic domainSource (opens in a new tab)

Discovery timeline

  1. 1878 · Formally described

    Marsh names Diplodocus

    Marsh names Diplodocus longus from fragmentary material from Garden Park, Colorado.

    People: Othniel Charles Marsh

  2. 1899 · Specimen recovered

    Carnegie Museum crew finds CM 84 at Sheep Creek

    A large, well-preserved Diplodocus skeleton is excavated in Albany County, Wyoming.

  3. 1901 · Formally described

    Hatcher names Diplodocus carnegii

    Hatcher names the species after Andrew Carnegie.

    People: John Bell Hatcher

  4. 2018 · Revision

    ICZN keeps D. longus as the type species of Diplodocus

    A proposal to make D. carnegii the type species is rejected.

Sources

  1. (2026). Paleobiology Database: Diplodocus occurrences. The Paleobiology Database (paleobiodb.org), data service 1.2, accessed 2026-09-23. https://paleobiodb.org/data1.2/occs/list.txt?base_name=Diplodocus&show=coords,paleoloc,strat,loc,ref&pgm=gplates (opens in a new tab)
  2. (2026). Wikipedia: Diplodocus. Wikipedia (English), accessed 2026-09-23. https://en.wikipedia.org/wiki/Diplodocus (opens in a new tab)
  3. Conti, S., Tschopp, E., Mateus, O., Zanoni, A., Masarati, P. & Sala, G. (2022). Multibody analysis and soft tissue strength refute supersonic dinosaur tail. Scientific Reports 12. doi:10.1038/s41598-022-21633-2 (opens in a new tab)
  4. Hatcher, J. B. (1901). Diplodocus (Marsh): its osteology, taxonomy, and probable habits, with a restoration of the skeleton. Memoirs of the Carnegie Museum 1: 1-63. doi:10.5962/p.234818 (opens in a new tab)
  5. International Commission on Zoological Nomenclature (2018). Opinion 2425 (Case 3700) – Diplodocus Marsh, 1878 (Dinosauria, Sauropoda): Diplodocus longus Marsh, 1878 maintained as the type species. Bulletin of Zoological Nomenclature 75. https://www.biotaxa.org/bzn/article/view/44176 (opens in a new tab)
  6. Marsh, O. C. (1878). Principal characters of American Jurassic dinosaurs. Part I. American Journal of Science, series 3, 16: 411-416.
  7. Myhrvold, N. P. & Currie, P. J. (1997). Supersonic sauropods? Tail dynamics in the diplodocids. Paleobiology 23: 393-409. doi:10.1017/s0094837300019801 (opens in a new tab)
  8. Paul, G. S. (2016). The Princeton Field Guide to Dinosaurs (2nd edition). Princeton University Press.
  9. Tschopp, E., Mateus, O. & Benson, R. B. J. (2015). A specimen-level phylogenetic analysis and taxonomic revision of Diplodocidae (Dinosauria, Sauropoda). PeerJ 3: e857. doi:10.7717/peerj.857 (opens in a new tab)