Open Paleo

Megalosaurus

Mantell, 1827 MEG-a-lo-SAWR-us

From Greek 'megas' (big, tall, or great) and 'sauros' (lizard); meaning 'great lizard'.

168.2–165.3 million years ago Bathonian, Middle Jurassic
Middle Jurassic stages

Megalosaurus is an extinct genus of large carnivorous theropod dinosaurs of the Middle Jurassic Epoch (Bathonian stage, 166 million years ago) of southern England. Although fossils from other areas have been assigned to the genus, the only certain remains of Megalosaurus come from Oxfordshire and date to the late Middle Jurassic.

Diagnosis

  1. Dentary with 13-14 teeth, an unexpanded third alveolus, and a straight dorsal profile with an unexpanded symphysial area
  2. Lateral row of dentary neurovascular foramina housed in a shallow longitudinal groove; interdental plates tall and unfused; two Meckelian foramina; Meckelian groove shallow
  3. Ventral surfaces of the first and third to fifth sacral centra evenly rounded, with a longitudinal angular ridge on the ventral surface of the second sacral centrum
  4. Dorsally directed flange around midheight of the scapular blade
  5. Array of posterodorsally inclined grooves on the lateral surface of the median iliac ridge; anteroposteriorly thick ischial apron with an almost flat medial surface and a prominent, rugose distal ischial tubercle
  6. Complementary groove-and-ridge structures on the articular surfaces between metatarsals II and III

Species

Megalosaurus bucklandii Mantell, 1827

Type species

Named for William Buckland, the English geologist and theologian who first scientifically described the genus in 1824.

Lectotype
OUMNH PAL-J.013505 , Oxford University Museum of Natural History
Material
Almost complete right dentary.
Notes
The lectotype includes the part and counterpart of the rock that held the dentary, which preserve fragments of its bone (Benson and colleagues, 2008). The designation by Molnar and colleagues (1990) made the rest of the material Buckland (1824) figured paralectotypes. They are unassociated, come from more than one individual, and some can no longer be traced; Benson and colleagues (2008) refer none of them to M. bucklandii with certainty and restrict the species to the lectotype.
Horizon
Taynton Limestone Formation, Bathonian, Middle Jurassic , 168.2–165.3 million years ago
Locality
Stonesfield, Oxfordshire, United Kingdom

Synonyms of the genus

Name Type Reason
Scrotum nomen oblitum Brookes (1763) figured the distal end of a femur under this name. Olshevsky (1991) records it as a nomen oblitum, the name having gone unused far beyond the interval that would allow it to displace Megalosaurus, and later listings treat the material as an indeterminate theropod femur.

References

  1. Olshevsky, G. (1991). A revision of the parainfraclass Archosauria Cope, 1869, excluding the advanced Crocodylia. Mesozoic Meanderings 2: 1-196.

    Records Scrotum as a nomen oblitum.

    olshevsky1991a
  2. Buckland, W. (1824). Notice on the Megalosaurus or great Fossil Lizard of Stonesfield. Transactions of the Geological Society of London 2(1 (2)): 390-396. doi:10.1144/transgslb.1.2.390

    First valid naming of any non-avian dinosaur genus; based on material from Stonesfield, Oxfordshire.

    buckland1824a
  3. Mantell, G. (1827). Illustrations of the geology of Sussex: a general view of the geological relations of the southeastern part of England, with figures and descriptions of the fossils of Tilgate Forest. 92. Fellow of the Royal College of Surgeons.

    First publication of the type-species binomial Megalosaurus bucklandii, honoring Buckland.

    mantell1827a
  4. Meyer, C. E. H. (1832). Palaeologica zur Geschichte der Erde. 560 pp. Verlag von Siegmund Schmerber.

    In German. On p. 110, Meyer introduces the variant spelling Megalosaurus bucklandi (sometimes erroneously ascribed to von Ritgen); the original Mantell (1827) spelling bucklandii has priority.

    meyer1832a
  5. Molnar, R. E.; Kurzanov, S. M.; Dong, Z. (1990). Carnosauria. The Dinosauria (Weishampel, D. B.; Dodson, P.; Osmólska, H., eds.) 169-209. University of California Press, Berkeley.

    Chapter in Weishampel, Dodson and Osmólska (eds.), first edition of The Dinosauria; designates OUMNH PAL-J.013505 as the lectotype of Megalosaurus bucklandii.

    molnar1990a
  6. 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(4): 882-935. Oxford University Press (OUP). doi:10.1111/j.1096-3642.2009.00569.x

    Comprehensive redescription and autapomorphy-based diagnosis of Megalosaurus bucklandii, restricting the taxon to the Bathonian of Britain; includes a phylogenetic analysis of basal tetanurans.

    benson2010c
  7. Brookes, R. (1763). A New and Accurate System of Natural History: The Natural History of Waters, Earths, Stones, Fossils, and Minerals with their Virtues, Properties and Medicinal Uses, to which is added, the Method in which Linnaeus has treated these subjects. 5: 364. J. Newberry, London. brookes1763a
  8. 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(2): 419-424. doi:10.1111/j.1475-4983.2008.00751.x

    Rediagnoses Megalosaurus bucklandii on the lectotype dentary alone, restricting the species to it.

    benson2008c
  9. Nicholls, E. L.; Newell, S. M.; Howlett, E. A. (2025). History of the Megalosaurus type material on public display. Earth Sciences History 44(1): 267-292. doi:10.17704/1944-6187-44.1.267

    Traces the type series at Oxford, gives catalog numbers for the nine surviving paralectotypes, and counts the dentary's matrix as part of the lectotype.

    nicholls2025a