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Stegosaurus with two alternating rows of plates and a spiked tail, in side view
Life restoration of Stegosaurus stenops based on the 'Sophie' specimen.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)

Stegosaurus stenops

Pronounced STEG-oh-SORE-us STEN-ops

Thyreophora ยท Stegosauridae

A plated thyreophoran from the Late Jurassic Morrison Formation of the western United States, with two rows of tall bony plates along its back and four tail spikes. Known from the exceptionally complete specimen "Sophie".

  • Armored
  • Quadrupedal
  • Famous specimen
  • Unusual anatomy
  • Movie icon
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Period
Jurassicยท Kimmeridgian
Diet
Herbivore
Length
6.5 m
Mass
1,560 kgpublished range 1,080โ€“2,260 kg
Location
Colorado, Wyoming

Quick answers

How big was Stegosaurus stenops?
Stegosaurus stenops was about 6.5 m long. It stood about 2โ€“2.6 m tall at the hips. It weighed about 1.1โ€“2.3 t. (Paul 2016; Brassey et al. 2015)
When did Stegosaurus stenops live?
Stegosaurus stenops lived during the Late Jurassic, about 154.8โ€“145 million years ago. (Cohen et al. 2023; Maidment et al. 2015)
Where have Stegosaurus stenops fossils been found?
Fossils of Stegosaurus stenops have been found in Morrison Formation (Colorado) and Wyoming. (Marsh 1887; Maidment et al. 2015)
What did Stegosaurus stenops eat?
Stegosaurus stenops was a herbivore. (Marsh 1887; Maidment et al. 2015)
Who named Stegosaurus stenops, and when?
Stegosaurus stenops was described by Othniel Charles Marsh in 1887. (Marsh 1887)
Was Stegosaurus stenops in Jurassic Park?
Yes. Stegosaurus stenops appears in The Lost World: Jurassic Park (1997), Jurassic Park III (2001), Jurassic World (2015), Jurassic World: Fallen Kingdom (2018), and Jurassic World Dominion (2022). Plated herbivores that defend their young in The Lost World, then brief appearances in each later film. Jurassic World shows the tail dragging low; the skeleton points to a tail held more horizontally. (Wikipedia: Dinosaurs in Jurassic Park 2026; Maidment et al. 2015)

On this page

STEG-oh-SORE-us STEN-ops

Period
Jurassic154.8โ€“145 Ma
Diet
Herbivore
Length
6.5 m
Mass
1.6 t
Classification
Thyreophora ยท Stegosauridae
Described
1887, Othniel Charles Marsh

Overview

Stegosaurus stenops lived in western North America in the Late Jurassic, and its fossils come from the Morrison Formation. O. C. Marsh named the species in 1887 from a nearly complete, articulated skeleton (USNM 4934) collected at Garden Park, Colorado.

It was a four-legged plant eater with a small, narrow head, two alternating rows of large plates along its back and two pairs of spikes at the end of the tail. The best-known individual, NHMUK PV R36730 ("Sophie"), from Red Canyon Ranch in Wyoming, is about 85 percent complete; Maidment et al. (2015) found it was not fully grown.

Brassey et al. (2015) modelled Sophie's volume and estimated about 1.6 tonnes, noting that equations based on limb bones give much higher values. Full-grown animals were larger.

Name meaning

From Greek stegos ("roof") and sauros ("lizard"), as Marsh first thought the plates lay flat like roof tiles; stenops means "narrow face" (Marsh 1887).

Biology & evidence

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

Behavior

  • Stegosaurus used its tail spikes to defend itself against predators such as Allosaurus.

    Evidence level: Strong evidence

    An Allosaurus bone has a hole that matches a Stegosaurus spike, and many spikes are broken and healed at the tip. Both show the spikes hit things hard, and the most likely targets were predators.

    Evidence for / against ยท 2
    Evidence for

    • Specimen ยท Allosaurus vertebra pierced by a Stegosaurus spike

      An Allosaurus tail vertebra with a healed puncture matching the size and shape of a Stegosaurus tail spike.

    • Specimen ยท Damaged and broken Stegosaurus tail spikes

      A notable share of Stegosaurus tail spikes are broken and remodelled at the tip, consistent with use in impacts.

Other

  • The plates of Stegosaurus were mainly for display.

    Evidence level: Hypothesis

    The plates were probably too thin to protect and their blood vessels are what any growing bone needs. Display or recognition is the leading idea, with heat control a possible side effect, but a function cannot be observed in fossils.

    Evidence for / against ยท 1
    Evidence for

    • Histology ยท Stegosaurus plate histology

      Thin sections of the plates show thin bone with many blood channels; the internal structure fits growth of a keratin-covered display structure better than a dedicated radiator.

  • The plates of Stegosaurus stood in two staggered rows along its back.

    Evidence level: Direct evidence

    Skeletons found with the plates still in position show the arrangement directly: two rows, offset from each other.

    Evidence for / against ยท 1
    Evidence for

Size

Length
6.5 m

(21.3 ft)

Height
2.3 mpublished range 2โ€“2.6 m

(7.5 ft)

Based on NHMUK PV R36730 ("Sophie")

Mass
1,560 kgpublished range 1,080โ€“2,260 kg

Based on NHMUK PV R36730 "Sophie" (not fully grown)

Stegosaurus stenops was about 6.5 m (21.3 ft) long, roughly 3.6 times the height of a 1.8 m adult human.

Timeline

Lived from about 154.8 to 145 million years ago (Ma), within the Mesozoic era (252โ€“66 Ma).

Periods: Kimmeridgian (154.8โ€“149.2 Ma), Tithonian (149.2โ€“145 Ma), Late Jurassic (161.5โ€“145 Ma)

Ages are the ICS 2023/09 bounds of the Kimmeridgian and Tithonian, the stage(s) the fossils are assigned to; they bracket the record and are not dated first/last appearances.

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

156โ€“147 million years ago ยท 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

Jurassicยท KimmeridgianCarnivore

Same ecosystem

Brachiosaurus altithorax

Jurassicยท KimmeridgianHerbivore

Same ecosystem

Brontosaurus excelsus

Jurassicยท KimmeridgianHerbivore

Same ecosystem

Diplodocus carnegii

Jurassicยท KimmeridgianHerbivore

Same ecosystem

Apatosaurus ajax

Jurassicยท KimmeridgianHerbivore

Same ecosystem

Ceratosaurus nasicornis

Jurassicยท KimmeridgianCarnivore

Classification

  1. cladeDinosauria
  2. cladeOrnithischia
  3. cladeThyreophora
  4. familyStegosauridae
  5. genusStegosaurus
  6. speciesStegosaurus stenops

Taxonomic status: Valid

Fossil record

Tail and spikes of 'Sophie' (NHMUK PV R36730), one of the most complete Stegosaurus stenops specimens, at the Natural History Museum, London.Image credit: Emล‘ke Dรฉnes, CC BY-SA 4.0, via Wikimedia Commons (unmodified except resizing), Natural History Museum, LondonCC BY-SA 4.0 (unmodified)Source (opens in a new tab)
Specimens
Catalog numberStatusInstitutionFound
USNM 4934 โ€œRoad Killโ€HolotypeNational Museum of Natural History, Smithsonian Institution (USNM)1886
NHMUK PV R36730 โ€œSophieโ€Referred specimenNatural History Museum, London (NHMUK)2003

What has been found

Holotype: USNM 4934 โ€œRoad Killโ€

  • Preserved
  • Partial
  • Reconstructed
  • Unknown / not recorded

Holotype: USNM 4934 โ€œRoad Killโ€

Region by region (table)
Skeleton regions of Holotype: USNM 4934 โ€œRoad Killโ€
RegionState
SkullPreserved
MandibleUnknown / not recorded
TeethUnknown / not recorded
Cervical vertebraePreserved
Dorsal vertebraePreserved
SacrumUnknown / not recorded
Caudal vertebraePartial
RibsUnknown / not recorded
GastraliaUnknown / not recorded
Scapula / shoulder girdleUnknown / not recorded
HumerusPreserved
Forearm (radius / ulna)Unknown / not recorded
Hand (manus)Unknown / not recorded
PelvisPartial
FemurPreserved
Tibia / fibulaUnknown / not recorded
Foot (pes)Unknown / not recorded

Referred specimen: NHMUK PV R36730 โ€œSophieโ€

Region by region (table)
Skeleton regions of Referred specimen: NHMUK PV R36730 โ€œSophieโ€
RegionState
SkullPreserved
MandiblePreserved
TeethUnknown / not recorded
Cervical vertebraePreserved
Dorsal vertebraePreserved
SacrumUnknown / not recorded
Caudal vertebraePreserved
RibsPreserved
GastraliaUnknown / not recorded
Scapula / shoulder girdleUnknown / not recorded
HumerusPreserved
Forearm (radius / ulna)Preserved
Hand (manus)Unknown / not recorded
PelvisPreserved
FemurPreserved
Tibia / fibulaPreserved
Foot (pes)Partial
Head and neck of a Stegosaurus skeleton reconstruction at the Senckenberg Museum, Frankfurt, showing the small skull and throat ossicles.Image credit: EvaK, CC BY-SA 2.5, via Wikimedia Commons (unmodified except resizing), Senckenberg NaturmuseumCC BY-SA 2.5 (unmodified)Source (opens in a new tab)

Gallery

Historical reconstruction: Charles R. Knight's Field Museum painting of Stegosaurus, with a drooping tail now considered outdated.Image credit: Charles R. Knight, Public domain, via Wikimedia CommonsPublic domain

All specimens

Discovery

Year described
1887
Described by
Othniel Charles Marsh
Type specimen
USNM 4934
The Stegosaurus stenops holotype USNM 4934 as it was found, figured by Charles W. Gilmore (1914).Image credit: Charles W. Gilmore, Public domain, via Wikimedia CommonsPublic domainSource (opens in a new tab)

Discovery timeline

  1. 1886 ยท Specimen recovered

    Felch finds the "Road Kill" Stegosaurus at Garden Park

    Marshall Felch collects an articulated Stegosaurus for Marsh in Garden Park, Colorado.

    People: Marshall P. Felch

  2. 1887 ยท Formally described

    Marsh names Stegosaurus stenops

    Marsh describes the skull and armour of Stegosaurus and names S. stenops.

    People: Othniel Charles Marsh

  3. 2013 ยท Revision

    S. stenops made the type species of Stegosaurus

    After a petition by Galton (2010), the ICZN replaces the undiagnostic S. armatus with S. stenops as the type species.

  4. 2015 ยท Major study

    Sophie described

    The most complete Stegosaurus is described and its mass estimated.

In Jurassic Park & Jurassic World

Films

  • The Lost World: Jurassic Park (1997)
  • Jurassic Park III (2001)
  • Jurassic World (2015)
  • Jurassic World: Fallen Kingdom (2018)
  • Jurassic World Dominion (2022)

On screen

Plated herbivores that defend their young in The Lost World, then brief appearances in each later film.

Film vs fossils

  • Jurassic World shows the tail dragging low; the skeleton points to a tail held more horizontally.
  • The tail spikes were real weapons: an Allosaurus tail bone carries a wound that matches a Stegosaurus spike.

Film titles are used for identification only. DinoDex is not affiliated with or endorsed by the Jurassic Park / Jurassic World franchise. All dinosaurs seen in the films

Sources

  1. (2026). Wikipedia: Dinosaurs in Jurassic Park. Wikipedia. https://en.wikipedia.org/wiki/Dinosaurs_in_Jurassic_Park (opens in a new tab)
  2. Brassey, C. A., Maidment, S. C. R. & Barrett, P. M. (2015). Body mass estimates of an exceptionally complete Stegosaurus (Ornithischia: Thyreophora): comparing volumetric and linear bivariate mass estimation methods. Biology Letters 11(3): 20140984. doi:10.1098/rsbl.2014.0984 (opens in a new tab)
  3. Carpenter, K., Sanders, F., McWhinney, L. A. & Wood, L. (2005). Evidence for predator-prey relationships: examples for Allosaurus and Stegosaurus. In Carpenter, K. (ed.), The Carnivorous Dinosaurs, Indiana University Press, pp. 325-350.
  4. Cohen, K. M., Harper, D. A. T., Gibbard, P. L. & Car, N. (2023). International Chronostratigraphic Chart (v2023/09). International Commission on Stratigraphy. https://stratigraphy.org/ICSchart/ChronostratChart2023-09.pdf (opens in a new tab)
  5. Maidment, S. C. R., Brassey, C. & Barrett, P. M. (2015). The postcranial skeleton of an exceptionally complete individual of the plated dinosaur Stegosaurus stenops (Dinosauria: Thyreophora) from the Upper Jurassic Morrison Formation of Wyoming, U.S.A.. PLoS ONE 10(10): e0138352. doi:10.1371/journal.pone.0138352 (opens in a new tab)
  6. Marsh, O. C. (1887). Principal characters of American Jurassic dinosaurs. Part IX. The skull and dermal armor of Stegosaurus. American Journal of Science (series 3) 34: 413-417.
  7. Paul, G. S. (2016). The Princeton Field Guide to Dinosaurs (2nd edition). Princeton University Press.