# Oxford Clay

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, 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

The Oxford Clay is well known for its rich fossil record of fish and invertebrates. 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.

## Fossil Content

| 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

Indeterminate euronithopod remains stratigraphically present in the Lower Oxford Clay and geographically located in Cambridgeshire, England.
Ornithischians of the Oxford Clay :
| Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
| Callovosaurus | C. leedsi | Cambridgeshire | Lower | "Femur." | An iguanodontian dryosaur. | Callovosaurus Lexovisaurus |
| Lexovisaurus | L. durobivensis | Cambridgeshire Dorset | Lower | A holotype pelvis. | A stegosaur | Callovosaurus Lexovisaurus |
| Lexovisaurus | Indeterminate | Bedfordshire | | | A stegosaur | Callovosaurus Lexovisaurus |
| Loricatosaurus | L. priscus | Cambridgeshire | Lower | | A stegosaur. | Callovosaurus Lexovisaurus |
| Sarcolestes | S. leedsi | Cambridgeshire | Lower | "Partial mandible." | An ankylosaur. | Callovosaurus Lexovisaurus |

### Saurischians

Saurischians of the Oxford Clay :
| Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
| Cetiosauriscus | C. stewarti | Cambridgeshire | Lower | "Rear half of a skeleton." | | Cetiosauriscus Eustreptospondylus Metriacanthosaurus |
| Eustreptospondylus | E. oxoniensis | Oxfordshire | Upper | Disarticulated skull and skeleton, with some referred limb elements. | | Cetiosauriscus Eustreptospondylus Metriacanthosaurus |
| Sauropoda | Indeterminate | Wiltshire Cambridgeshire | | | The caudal vertebrae from Cambridgeshire were mistakenly considered part of the syntypic series of "Ornithopsis" leedsi by Upchurch and Martin (2003). | Cetiosauriscus Eustreptospondylus Metriacanthosaurus |
| Theropoda | Indeterminate | Oxfordshire | Middle | | | Cetiosauriscus Eustreptospondylus Metriacanthosaurus |
| Metriacanthosaurus | M. parkeri | Weymouth | Upper | | | Cetiosauriscus Eustreptospondylus Metriacanthosaurus |

### Ichthyosaurs

| Genus | Species | Location | Member | Abundance | Notes | Images |
| Ophthalmosaurus | O. icenicus | | | | A ophthalmosaurid ichthyosaur |

### Plesiosaurs

| Genus | Species | Notes | Images |
| Cryptoclidus | C. eurymerus | A cryptoclidid | Cryptoclidus Eardasaurus Liopleurodon Muraenosaurus Pachycostasaurus Peloneustes Simolestes |
| Cryptoclidus | C. richardsoni | A cryptoclidid | Cryptoclidus Eardasaurus Liopleurodon Muraenosaurus Pachycostasaurus Peloneustes Simolestes |
| Eardasaurus | E. powelli | A thalassophonean pliosaurid | Cryptoclidus Eardasaurus Liopleurodon Muraenosaurus Pachycostasaurus Peloneustes Simolestes |
| Liopleurodon | L. ferox | A thalassophonean pliosaurid | Cryptoclidus Eardasaurus Liopleurodon Muraenosaurus Pachycostasaurus Peloneustes Simolestes |
| Liopleurodon | L. pachydeirus | A thalassophonean pliosaurid | Cryptoclidus Eardasaurus Liopleurodon Muraenosaurus Pachycostasaurus Peloneustes Simolestes |
| Marmornectes | M. candrewi | A pliosaurid | Cryptoclidus Eardasaurus Liopleurodon Muraenosaurus Pachycostasaurus Peloneustes Simolestes |
| Muraenosaurus | M. leedsi | A cryptoclidid | Cryptoclidus Eardasaurus Liopleurodon Muraenosaurus Pachycostasaurus Peloneustes Simolestes |
| Pachycostasaurus | P. dawnii | A pliosaurid | Cryptoclidus Eardasaurus Liopleurodon Muraenosaurus Pachycostasaurus Peloneustes Simolestes |
| Peloneustes | P. philarchus | A thalassophonean pliosaurid | Cryptoclidus Eardasaurus Liopleurodon Muraenosaurus Pachycostasaurus Peloneustes Simolestes |
| Picrocleidus | P. beloclis | A cryptoclidid | Cryptoclidus Eardasaurus Liopleurodon Muraenosaurus Pachycostasaurus Peloneustes Simolestes |
| Pliosaurus | P. andrewsi | A thalassophonean pliosaurid; represents a new genus distinct from Pliosaurus | Cryptoclidus Eardasaurus Liopleurodon Muraenosaurus Pachycostasaurus Peloneustes Simolestes |
| Simolestes | S. vorax | A thalassophonean pliosaurid | Cryptoclidus Eardasaurus Liopleurodon Muraenosaurus Pachycostasaurus Peloneustes Simolestes |
| Tricleidus | T. seeleyi | A cryptoclidid | Cryptoclidus Eardasaurus Liopleurodon Muraenosaurus Pachycostasaurus Peloneustes Simolestes |

### Pachycormiformes

| Genus | Species | Notes |
| 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

| Genus | Species | Notes | Images |
| Lemmysuchus | L. obtusidens | A teleosauroid belonging to the Machimosauridae | Neosteneosaurus specimen (from an unknown location) Thalattosuchus Suchodus Tyrannoneustes |
| Charitomenosuchus | C. leedsi | A machimosaurid teleosauroid | Neosteneosaurus specimen (from an unknown location) Thalattosuchus Suchodus Tyrannoneustes |
| Steneosaurus | S. edwardsi | Now referred to Neosteneosaurus. | Neosteneosaurus specimen (from an unknown location) Thalattosuchus Suchodus Tyrannoneustes |
| Steneosaurus | S. durobrivensis | Junior synonym of N. edwardsi. | Neosteneosaurus specimen (from an unknown location) Thalattosuchus Suchodus Tyrannoneustes |
| Neosteneosaurus | N. edwardsi | A machimosaurid teleosauroid | Neosteneosaurus specimen (from an unknown location) Thalattosuchus Suchodus Tyrannoneustes |
| Mycterosuchus | M. leedsi | A teleosaurid teleosauroid | Neosteneosaurus specimen (from an unknown location) Thalattosuchus Suchodus Tyrannoneustes |
| Metriorhynchus | M. superciliosus | This species was referred to a new genus, Thalattosuchus. | Neosteneosaurus specimen (from an unknown location) Thalattosuchus Suchodus Tyrannoneustes |
| Thalattosuchus | T. superciliosus | A metriorhynchine metriorhynchid | Neosteneosaurus specimen (from an unknown location) Thalattosuchus Suchodus Tyrannoneustes |
| Gracilineustes | G. leedsi | A metriorhynchine metriorhynchid | Neosteneosaurus specimen (from an unknown location) Thalattosuchus Suchodus Tyrannoneustes |
| Suchodus | S. brachyrhynchus | A geosaurine metriorhynchid | Neosteneosaurus specimen (from an unknown location) Thalattosuchus Suchodus Tyrannoneustes |
| Suchodus | S. durobrivensis | A geosaurine metriorhynchid | Neosteneosaurus specimen (from an unknown location) Thalattosuchus Suchodus Tyrannoneustes |
| Tyrannoneustes | T. lythrodectikos | A geosaurine metriorhynchid | Neosteneosaurus specimen (from an unknown location) Thalattosuchus Suchodus Tyrannoneustes |

## Economic use

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.