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Theropod with a colourful head striding in side view
Life restoration of Megalosaurus bucklandii, the first non-avian dinosaur to be named.Image credit: Federico benzan, CC BY-SA 4.0, via Wikimedia Commons (unmodified except resizing)CC BY-SA 4.0 (unmodified)Source (opens in a new tab)

Megalosaurus bucklandii

Pronounced MEG-ah-loh-SORE-us buk-LAN-dee-eye

Tetanurae · Megalosauridae

A large meat-eating dinosaur from the Middle Jurassic of Oxfordshire, England, and the first dinosaur to be scientifically named, by William Buckland in 1824. Its type specimen is a lower jaw kept in Oxford.

  • Bipedal
  • Famous specimen
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Period
Jurassic· Middle Jurassic
Diet
Carnivore
Length
6 m
Mass
700–943 kg
Location
Oxfordshire, United Kingdom

Quick answers

How big was Megalosaurus bucklandii?
Megalosaurus bucklandii was about 6 m long. It stood about 1.8–2.1 m tall at the hips. It weighed about 700–943 kg. (Paul 2010; Wikipedia: Megalosaurus 2026)
When did Megalosaurus bucklandii live?
Megalosaurus bucklandii lived during the Middle Jurassic, about 168.2–165.3 million years ago. (Paleobiology Database: Megalosaurus occurrences 2026)
Where have Megalosaurus bucklandii fossils been found?
Fossils of Megalosaurus bucklandii have been found in Taynton Limestone Formation (Oxfordshire) and United Kingdom. (Buckland 1824; Benson et al. 2008)
What did Megalosaurus bucklandii eat?
Megalosaurus bucklandii was a carnivore. (Buckland 1824; Benson et al. 2008)
Who named Megalosaurus bucklandii, and when?
Megalosaurus bucklandii was described by William Buckland in 1824. (Buckland 1824; History 2026)

On this page

Period
Jurassic168.2–165.3 Ma
Diet
Carnivore
Length
6 m
Mass
0.7–0.9 t
Location
United Kingdom
Classification
Tetanurae · Megalosauridae
Described
1824, William Buckland

Overview

Megalosaurus bucklandii lived in what is now southern England in the Middle Jurassic (Bathonian), on a coastline with lagoons and seasonal dry spells. Bones from the quarries around Stonesfield, north-west of Oxford, reached the University of Oxford from the 1790s; William Buckland described them in 1824 as the "great fossil lizard", and Gideon Mantell added the species name bucklandii in 1827.

It was a two-legged predator several metres long with blade-like, serrated teeth. Its jaw (OUMNH PAL-J.13505) is the type specimen. In 1842 Richard Owen used Megalosaurus, Iguanodon and Hylaeosaurus to define a new group, the Dinosauria.

For a long time almost any large Jurassic or Cretaceous theropod was called Megalosaurus. Benson and colleagues (2008) showed that the type jaw has unique features, so the species is valid, but warned that other bones could not be referred to it with certainty; a larger study (Benson 2010) later described more of the Stonesfield material as Megalosaurus.

Name meaning

"Great lizard", from Greek megas ("great") and sauros ("lizard") (Buckland 1824); bucklandii honours William Buckland (Mantell 1827).

Biology & evidence

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

Other

  • Megalosaurus was one of the three animals used to define the Dinosauria in 1842.

    Evidence level: Direct evidence

    Richard Owen coined "Dinosauria" in 1842 for Megalosaurus, Iguanodon and Hylaeosaurus. This is a historical fact, not a biological inference.

    Evidence for / against · 1
    Evidence for

    • Specimen · Megalosaurus lectotype dentary

      A right dentary diagnosed by two unique characters: a groove along the lower outer surface and a slit-like anterior Meckelian foramen.

      Specimen: OUMNH PAL-J.13505

  • Only the type jaw can be assigned to Megalosaurus bucklandii with certainty.

    Evidence level: Disputed

    In 2008 Benson and colleagues found no other bones that could be referred to the species with certainty. In 2010 Benson described much of the Stonesfield material as Megalosaurus, so the question depends on how much variation one accepts.

    Evidence for / against · 2
    Evidence for

    • Specimen · Megalosaurus lectotype dentary

      A right dentary diagnosed by two unique characters: a groove along the lower outer surface and a slit-like anterior Meckelian foramen.

      Specimen: OUMNH PAL-J.13505

    Evidence against

    • Comparative anatomy · Megalosaurus Stonesfield skeleton description

      A full description of the Stonesfield theropod bones treated as Megalosaurus bucklandii.

  • Megalosaurus was the first dinosaur to be scientifically described.

    Evidence level: Strong evidence

    Buckland described it in 1824, a year before Mantell named Iguanodon. An earlier printed mention (Parkinson 1822) had no description.

    Evidence for / against · 1
    Evidence for

    • Specimen · Megalosaurus lectotype dentary

      A right dentary diagnosed by two unique characters: a groove along the lower outer surface and a slit-like anterior Meckelian foramen.

      Specimen: OUMNH PAL-J.13505

Size

Length
6 m

(19.7 ft)

Height
1.9 mpublished range 1.8–2.1 m

(6.2 ft)

Based on OUMNH J13561 (femur c. 0.8 m) and Stonesfield material

Mass
700–943 kg

Based on NHMUK PV OR 31806 (femur 803 mm) for the upper value

Megalosaurus bucklandii was about 6 m (19.7 ft) long, roughly 3.3 times the height of a 1.8 m adult human.

Timeline

Lived from about 168.2 to 165.3 million years ago (Ma), within the Mesozoic era (252–66 Ma).

Periods: Middle Jurassic (174.7–161.5 Ma)

Middle Bathonian bounds of the Stonesfield collection in PBDB.

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: Stonesfield (Taynton Limestone)

coastal plain, marine margin

A Middle Jurassic coastline in southern England, perhaps seasonally dry, with mangrove-like vegetation.

Classification

  1. cladeDinosauria
  2. cladeSaurischia
  3. cladeTheropoda
  4. cladeTetanurae
  5. superfamilyMegalosauroidea
  6. familyMegalosauridae
  7. genusMegalosaurus
  8. speciesMegalosaurus bucklandii

Taxonomic status: Valid

Fossil record

Replica of the Megalosaurus bucklandii lower jaw OUM J13505 from the Stonesfield quarry, England.Image credit: James St. John, CC BY 2.0, via Wikimedia CommonsCC BY 2.0Source (opens in a new tab)
Specimens
Catalog numberStatusInstitutionFound
OUMNH PAL-J.13505LectotypeOxford University Museum of Natural History (OUMNH)1797

What has been found

Lectotype: OUMNH PAL-J.13505

  • Preserved
  • Partial
  • Reconstructed
  • Unknown / not recorded
Region by region (table)
Skeleton regions of Lectotype: OUMNH PAL-J.13505
RegionState
SkullUnknown / not recorded
MandiblePartial · Right dentary.
TeethPartial
Cervical vertebraeUnknown / not recorded
Dorsal vertebraeUnknown / not recorded
SacrumUnknown / not recorded
Caudal vertebraeUnknown / not recorded
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
Skeletal diagram of Megalosaurus bucklandii showing only the bones that can be referred to the species.Image credit: Slate Weasel, CC BY-SA 4.0, via Wikimedia Commons (unmodified except resizing)CC BY-SA 4.0 (unmodified)Source (opens in a new tab)

Gallery

Historical reconstruction: Édouard Riou's 1863 engraving of Iguanodon fighting Megalosaurus, in the quadrupedal lizard-like style of the Crystal Palace models.Image credit: Édouard Riou, Public domain, via Wikimedia CommonsPublic domain

All specimens

Discovery

Year described
1824
Described by
William Buckland
Type specimen
OUMNH PAL-J.13505
19th-century plate of the Megalosaurus bucklandii dentary and teeth, from Richard Owen's monograph on British fossil reptiles.Image credit: J. Erxleben, Public domain, via Wikimedia CommonsPublic domainSource (opens in a new tab)

Discovery timeline

  1. 1797 · First material found

    Oxford acquires the Megalosaurus jaw

    A jaw from the Stonesfield quarries is acquired by the University of Oxford.

  2. 1824 · Formally described

    Buckland describes Megalosaurus

    Buckland presents the "great fossil lizard of Stonesfield" to the Geological Society of London.

    People: William Buckland

  3. 2008 · Revision

    Benson et al. confirm Megalosaurus bucklandii as a valid species

    The lectotype jaw is shown to have unique features.

    People: Roger B. J. Benson

Sources

  1. (2026). Paleobiology Database: Megalosaurus occurrences. The Paleobiology Database (paleobiodb.org), data service 1.2, accessed 2026-09-23. https://paleobiodb.org/data1.2/occs/list.txt?base_name=Megalosaurus&show=coords,paleoloc,strat,loc,ref&pgm=gplates (opens in a new tab)
  2. (2026). Wikipedia: Megalosaurus. Wikipedia (English), accessed 2026-09-23. https://en.wikipedia.org/wiki/Megalosaurus (opens in a new tab)
  3. Benson, R. B. J. (2010). A description of Megalosaurus bucklandii (Dinosauria: Theropoda) from the Bathonian of the UK and the relationships of Middle Jurassic theropods. Zoological Journal of the Linnean Society 158: 882-935. doi:10.1111/j.1096-3642.2009.00569.x (opens in a new tab)
  4. Benson, R. B. J., Barrett, P. M., Powell, H. P. & Norman, D. B. (2008). The taxonomic status of Megalosaurus bucklandii (Dinosauria, Theropoda) from the Middle Jurassic of Oxfordshire, UK. Palaeontology 51: 419-424. doi:10.1111/j.1475-4983.2008.00751.x (opens in a new tab)
  5. Buckland, W. (1824). Notice on the Megalosaurus or great Fossil Lizard of Stonesfield. Transactions of the Geological Society of London, series 2, 1: 390-396. doi:10.1144/transgslb.1.2.390 (opens in a new tab)
  6. Oxford University Museum of Natural History (2026). Megalosaurus dentary (OUMNH PAL-J.13505), 3D model and record. Sketchfab (museum account @morethanadodo). https://sketchfab.com/3d-models/megalosaurus-dentary-oumnh-pal-j13505-95c26e991aeb4ebfacd6ceec76e08cba (opens in a new tab)
  7. Paul, G. S. (2010). The Princeton Field Guide to Dinosaurs. Princeton University Press.
  8. Paul, G. S. (2016). The Princeton Field Guide to Dinosaurs (2nd edition). Princeton University Press.