Diplodocus carnegii

Diplodocus carnegii was a large diplodocid sauropod from the Late Jurassic Morrison Formation of Wyoming. It combined a small head, a long pneumatic neck, a deep but relatively slender torso and an extremely long tapering tail. Peg-like teeth were concentrated at the front of a broad muzzle and were replaced throughout life. The species is best represented by Carnegie Museum specimens CM 84 and CM 94. Their mounted reconstruction, popularly called Dippy, became one of the most widely reproduced dinosaur skeletons in history, but modern documentation shows that both the Pittsburgh mount and its casts combine original, cast and sculpted elements from several specimens.

Its fossils occur between approximately 154 and 152 million years ago. Values shown here are approximate and reflect the current curated seed dataset.

Holotype CM 84 preserves much of the neck, trunk, pelvis, tail and hind limbs but lacks a skull and several limb elements. Paratype CM 94 and other diplodocids informed missing portions of the historic mount. A 2025 specimen-by-specimen audit measured the current Pittsburgh mount at about 26.1 metres and identified original fossils, casts and sculptures throughout it. Diplodocus had paired, beam-like chevrons beneath many tail vertebrae, the feature that inspired the genus name 'double beam'. Air-filled spaces within the vertebrae reduced skeletal weight.

• Very long neck built from elongated, air-filled vertebrae
• Small skull with a broad, squared snout
• Slender peg-like teeth concentrated at the front of the jaws
• Deep torso carried on four columnar limbs
• Single enlarged claw on the inner digit of each hand
• Paired beam-like chevrons beneath much of the tail
• Extremely long, tapering tail forming roughly half the body length

Carnegie Museum crews working around Sheep Creek, Wyoming, located Diplodocus material in 1898. The skeleton catalogued as CM 84 was excavated in 1899 by a field crew that included Arthur Coggeshall, Jacob L. Wortman, William H. Reed and W. C. Reed. A second partial skeleton, CM 94, was collected from the same quarry in 1900. John Bell Hatcher described both in the first Memoirs of the Carnegie Museum in July 1901 and named D. carnegii for Andrew Carnegie. The original mount opened in Pittsburgh in 1907 and was scientifically remounted in 2007.

Discovery credit: Arthur Coggeshall, Jacob L. Wortman, William H. Reed, W. C. Reed.

Naming authors: John Bell Hatcher.

The Morrison Formation records broad river floodplains, seasonal streams, ponds and drier open areas under a strongly seasonal climate. Conifers, tree ferns, cycads, horsetails and low ferns supplied vegetation. Diplodocus shared this landscape with other sauropods such as Apatosaurus, Brontosaurus, Camarasaurus and Brachiosaurus, as well as Stegosaurus, smaller herbivores and predators including Allosaurus and Ceratosaurus.

The broad muzzle and dental microwear of diplodocoids support non-selective cropping, probably often at low or middle heights, while biomechanical work rejects some forceful bark-stripping scenarios. The long neck enlarged the feeding area without requiring the whole animal to move for every bite. Rearing and high browsing were physically possible in some models but are not directly demonstrated. Tail-whip functions, herd structure, mating displays and precise neck posture remain debated. Bone histology indicates rapid growth; paratype CM 94 was at least about 24 years old despite its enormous size.

• The original Dippy was so large that Carnegie expanded the museum around it—earning the building the nickname 'the house that Dippy built'.
• Carnegie donated plaster casts to museums across Europe and the Americas, making Dippy one of the world's most recognisable dinosaur skeletons.
• The current Pittsburgh mount is about 26.1 metres long and combines original fossils, casts and sculpted replacements.
• The spelling carnegii is Hatcher's original species name; carnegiei is a common later misspelling.
• Despite its huge body, the head was less than a metre long and carried narrow teeth only near the front of the jaws.

A research repository is not necessarily a public exhibit. Loan and display status can change, so check with the institution before visiting.

1. 01
   The Paleobiology Database

   Open source
2. 02
   Diplodocus (Marsh): its osteology, taxonomy, and probable habits, with a restoration of the skeleton

   John Bell Hatcher · Memoirs of the Carnegie Museum · 1901

   Open source
3. 03
   A specimen-level phylogenetic analysis and taxonomic revision of Diplodocidae

   Emanuel Tschopp, Octávio Mateus, Roger B. J. Benson · PeerJ · 2015

   Open source
4. 04
   Inferences of diplodocoid feeding behavior from snout shape and microwear analyses

   John A. Whitlock · PLOS ONE · 2011

   Open source
5. 05
   Cranial biomechanics of Diplodocus: testing hypotheses of feeding behaviour in an extinct megaherbivore

   Mark T. Young, Emily J. Rayfield, Casey M. Holliday and 4 coauthors · Naturwissenschaften · 2012

   Open source
6. 06
   A new multi-faceted framework for deciphering diplodocid ontogeny

   D. Cary Woodruff, Denver W. Fowler, John R. Horner · Palaeontologia Electronica · 2017

   Open source
7. 07
   The history and composition of the Carnegie Diplodocus

   Michael P. Taylor, Amy Henrici, Linsly Church and 2 coauthors · Annals of the Carnegie Museum · 2025

   Open source
8. 08
   Carnegie Museum of Natural History Diplodocus Collection

   Carnegie Mellon University Libraries

   Open source
9. 09
   Section of Vertebrate Paleontology

   Carnegie Museum of Natural History

   Open source