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Oxford Clay

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Oxford Clay
Stratigraphic range: Middle to Late Jurassic (Callovian-Oxfordian), 166–160 Ma
Coastal exposure of the Oxford Clay Formation near Weymouth
TypeGeological formation
Unit ofAncholme Group
Sub-unitsPeterborough Member, Stewartby Member, Weymouth Member
UnderliesWest Walton Formation, Corallian Group
OverliesKellaways Formation, Osgodby Formation
ThicknessUp to 185 metres, typically 50 to 70 m on East Midlands Shelf
Lithology
PrimaryClaystone
OtherMudstone
Location
RegionOxford, Peterborough, Dorset, Yorkshire
CountryEngland
Type section
Named forOxford

The Oxford Clay (or Oxford Clay Formation) is a Jurassic marine sedimentary rock formation underlying much of southeast England, from as far west as Dorset and as far north as Yorkshire. The Oxford Clay Formation dates to the Jurassic, specifically, the Callovian and Oxfordian ages,[1] and comprises two main facies. The lower facies comprises the Peterborough Member, a fossiliferous organic-rich mudstone. This facies and its rocks are commonly known as lower Oxford Clay. The upper facies comprises the middle Oxford Clay, the Stewartby Member, and the upper Oxford Clay, the Weymouth Member. The upper facies is a fossil poor assemblage of calcareous mudstones.

Oxford Clay appears at the surface around Oxford, Peterborough and Weymouth and is exposed in many quarries around these areas. The top of the Lower Oxford Clay shows a lithological change, where fissile shale changes to grey mudstone. The Middle and Upper Oxford Clays differ slightly, as they are separated by an argillaceous limestone in the South Midlands.

Palaeontology

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The Oxford Clay is well known for its rich fossil record of fish and invertebrates.[2] Many of the fossils are well preserved, occasionally some are found exceptionally well preserved. Animals which lived in the Oxford Clay Sea include plesiosaurs, marine crocodiles, ichthyosaurs, cephalopods (such as belemnites), bivalves (such as Gryphaea), and a variety of gastropods. Dinosaur eggs are stratigraphically present in the Lower Oxford Clay. Geographically, they are located in Cambridgeshire, England.[3]

Illustration of a theropod running towards a group of stegosaurs with spikes along their backs surrounded by forest
Life restoration of Eustreptospondylus and Lexovisaurus in the Oxford Clay environment

Ornithischians

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Indeterminate euronithopod remains stratigraphically present in the Lower Oxford Clay and geographically located in Cambridgeshire, England.[3]

Color key
Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon
Notes
Uncertain or tentative taxa are in small text; crossed out taxa are discredited.
Ornithischians of the Oxford Clay
Genus Species Location Stratigraphic position Material Notes Images

Callovosaurus

C. leedsi[3]

  • Cambridgeshire[3]

Lower[3]

"Femur."[4]

An iguanodontian dryosaur.
Callovosaurus
Lexovisaurus

Lexovisaurus[5]

L. durobivensis[6]

Lower[6]

A holotype pelvis. A stegosaur

Indeterminate[8]

  • Bedfordshire[9]

Loricatosaurus[3]

L. priscus[3]

  • Cambridgeshire[3]

Lower[3]

A stegosaur.

Sarcolestes[3]

S. leedsi[3]

  • Cambridgeshire[3]

Lower[3]

"Partial mandible."[10]

An ankylosaur.

Saurischians

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Color key
Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon
Notes
Uncertain or tentative taxa are in small text; crossed out taxa are discredited.
Saurischians of the Oxford Clay
Genus Species Location Stratigraphic position Material Notes Images

Cetiosauriscus[3]

C. stewarti[3]

  • Cambridgeshire[3]

Lower[3]

"Rear half of a skeleton."[11]

Cetiosauriscus
Eustreptospondylus
Metriacanthosaurus

Eustreptospondylus[12]

E. oxoniensis[12]

Upper[12]

Disarticulated skull and skeleton, with some referred limb elements.[13]

Sauropoda

Indeterminate[14]

The caudal vertebrae from Cambridgeshire were mistakenly considered part of the syntypic series of "Ornithopsis" leedsi by Upchurch and Martin (2003).[15]

Theropoda

Indeterminate[12]

Middle[12]

Metriacanthosaurus

M. parkeri
  • Weymouth
Upper

Ichthyosaurs

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Color key
Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon
Notes
Uncertain or tentative taxa are in small text; crossed out taxa are discredited.
Genus Species Location Member Abundance Notes Images

Ophthalmosaurus

O. icenicus

A ophthalmosaurid ichthyosaur

Plesiosaurs

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Color key
Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon
Notes
Uncertain or tentative taxa are in small text; crossed out taxa are discredited.
Genus Species Location Member Abundance Notes Images

Cryptoclidus

C. eurymerus

A cryptoclidid

Cryptoclidus
Eardasaurus
Liopleurodon
Muraenosaurus
Pachycostasaurus
Peloneustes
Simolestes

C. richardsoni

A cryptoclidid

Eardasaurus

E. powelli

A thalassophonean pliosaurid

Liopleurodon

L. ferox

A thalassophonean pliosaurid

L. pachydeirus

A thalassophonean pliosaurid

Marmornectes

M. candrewi

A pliosaurid

Muraenosaurus

M. leedsi

A cryptoclidid

Pachycostasaurus

P. dawnii

A pliosaurid

Peloneustes

P. philarchus

A thalassophonean pliosaurid

Picrocleidus

P. beloclis

A cryptoclidid

Pliosaurus

P. andrewsi

A thalassophonean pliosaurid; represents a new genus distinct from Pliosaurus

Simolestes

S. vorax

A thalassophonean pliosaurid

Tricleidus

T. seeleyi

A cryptoclidid

Pachycormiformes

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Color key
Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon
Notes
Uncertain or tentative taxa are in small text; crossed out taxa are discredited.
Genus Species Location Member Abundance Notes Images
Leedsichthys L. problematicus Giant filter feeding pachycormiform
Martillichthys M. renwickae Filter feeding pachyocormiform
"Hypsocormus" "H." tenuirostris Carnivorous pachycormiform, not closely related to Hypsocormus, and more closely related to Orthocormus

Thalattosuchians

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Color key
Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon
Notes
Uncertain or tentative taxa are in small text; crossed out taxa are discredited.
Genus Species Location Member Abundance Notes Images

Lemmysuchus

L. obtusidens

A teleosauroid belonging to the Machimosauridae

Neosteneosaurus
Thalattosuchus
Suchodus
Tyrannoneustes

Charitomenosuchus

C. leedsi

A machimosaurid teleosauroid

Steneosaurus

S. edwardsi

Now referred to Neosteneosaurus.

S. durobrivensis

Junior synonym of N. edwardsi.

Neosteneosaurus

N. edwardsi

A machimosaurid teleosauroid

Mycterosuchus

M. leedsi

A teleosaurid teleosauroid

Metriorhynchus

M. superciliosus

This species was referred to a new genus, Thalattosuchus.[16]

Thalattosuchus

T. superciliosus

A metriorhynchine metriorhynchid

Gracilineustes

G. leedsi

A metriorhynchine metriorhynchid

Suchodus

S. brachyrhynchus

A geosaurine metriorhynchid

S. durobrivensis

A geosaurine metriorhynchid

Tyrannoneustes[17]

T. lythrodectikos

A geosaurine metriorhynchid

Economic use

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Oxford Clay has a porous consistency and is soft and is often used in the making of roads. It is also the source of the Fletton stock brick of which much of London is built. For brick making, the Oxford Clay has the advantage of containing carbon which provides part of the fuel required in firing it so reducing the requirement for an external fuel source.

See also

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References

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  1. ^ "Oxford Clay Formation". The BGS Lexicon of Named Rock Units. British Geological Survey. Retrieved 21 August 2017.
  2. ^ Martill, D.M.; Hudson J.D. (1991). Fossils of the Oxford Clay. Palaeontological Association.
  3. ^ a b c d e f g h i j k l m n o p q r s "10.9 Cambridgeshire, England; 1. Lower Oxford Clay," in Weishampel, et al. (2004). Page 540.
  4. ^ "Table 18.1," in Weishampel, et al. (2004). Page 396.
  5. ^ Weishampel, et al. (2004). Pages 539-540.
  6. ^ a b "10.7 Dorset, England; 3. Lower Oxford Clay" and "cambridgeshire">"10.9 Cambridgeshire, England; 1. Lower Oxford Clay," in Weishampel, et al. (2004). Pages 539-540.
  7. ^ "10.7 Dorset, England; 3. Lower Oxford Clay," in Weishampel, et al. (2004). Page 539.
  8. ^ Listed as "?Lexovisaurus sp." in "10.10 Bedfordshire, England; 1. Oxford Clay," in Weishampel, et al. (2004). Page 540.
  9. ^ "10.10 Bedfordshire, England; 1. Oxford Clay," in Weishampel, et al. (2004). Page 540.
  10. ^ "Table 17.1," in Weishampel, et al. (2004). Page 367.
  11. ^ "Table 13.1," in Weishampel, et al. (2004). Page 265.
  12. ^ a b c d e f g "10.14 Oxfordshire, England; 8. Middle Oxford Clay," in Weishampel, et al. (2004). Page 540.
  13. ^ "Table 4.1," in Weishampel, et al. (2004). Page 72.
  14. ^ a b "10.14 Wiltshire, England; 4. Oxford Clay," in Weishampel, et al. (2004). Page 540.
  15. ^ Noé LF, Liston JJ, Chapman SD. 2010. ‘Old bones, dry subject’: the dinosaurs and pterosaur collected by Alfred Nicholson Leeds of Peterborough, England. Geological Society, London, Special Publications 343: 49–77.
  16. ^ Young, M.T.; Brignon, A.; Sachs, S.; Hornung, J.; Foffa, D.; Kitson, J.J.N.; Johnson, M.M.; Steel, L. (2021). "Cutting the Gordian knot: a historical and taxonomic revision of the Jurassic crocodylomorph Metriorhynchus". Zoological Journal of the Linnean Society. 192 (2): 510–553. doi:10.1093/zoolinnean/zlaa092.
  17. ^ Mark T. Young; Marco Brandalise de Andrade; Stephen L. Brusatte; Manabu Sakamoto; Jeff Liston (2013). "The oldest known metriorhynchid super-predator: a new genus and species from the Middle Jurassic of England, with implications for serration and mandibular evolution in predacious clades". Journal of Systematic Palaeontology. 11 (4): 475–513. doi:10.1080/14772019.2012.704948. S2CID 85276836.

Bibliography

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Further reading

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  • Andrews, C. W. 1910. "A Descriptive Catalogue of the Marine Reptiles of the Oxford Clay, Part I". British Museum (Natural History), London, England: 205 pp.
  • Andrews, CW. 1913. "A descriptive catalogue of the Marine Reptiles of the Oxford Clay, Part II". British Museum (Natural History). pp. 205pp.
  • M. J. Benton and P. S. Spencer. 1995. Fossil Reptiles of Great Britain. Chapman & Hall, London 1–386
  • J. B. Delair. 1973. "The dinosaurs of Wiltshire". The Wiltshire Archaeological and Natural History Magazine 68:1–7
  • P. M. Galton. 1980. "European Jurassic ornithopod dinosaurs of the families Hypsilophodontidae and Camptosauridae". Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen 160(1):73–95
  • D. M. Martill. 1988. "A review of the terrestrial vertebrate of fossils of the Oxford Clay (Callovian-Oxfordian) of England". Mercian Geologist 11(3):171–190