# Kimmeridge Clay

The Kimmeridge Clay is a sedimentary deposit of fossiliferous marine clay which is of Late Jurassic to lowermost Cretaceous age and occurs in southern and eastern England and in the North Sea. This rock formation is the major source rock for North Sea oil. The fossil fauna of the Kimmeridge Clay includes turtles, crocodiles, sauropods, plesiosaurs, pliosaurs and ichthyosaurs, as well as a number of invertebrate species.

## Description

Kimmeridge Clay is named after the village of Kimmeridge on the Dorset coast of England, where it is well exposed and forms part of the Jurassic Coast World Heritage Site. Onshore, it is of Late Jurassic (Kimmeridgian) age and outcrops across England, in a band stretching from Dorset in the south-west, north-east to North Yorkshire. Offshore, it extends into the Lower Cretaceous (Berriasian Stage) and it is found throughout the Southern, Central and Northern North Sea.
The foundations of the Humber Bridge on the southern (Barton) side of the bridge are on Kimmeridge Clay beneath superficial deposits, under the Humber estuary.

## Economic importance

Kimmeridge Clay is of great economic importance, being the major source rock for oil fields in the North Sea hydrocarbon province. It has distinctive physical properties and log responses.

## Vertebrate fauna

| 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. |
Fauna uncovered from the Kimmeridge Clay include:

### Ray-finned fish

Ray-finned fishes of the Kimmeridge clay Formation :
| Genus | Species | Location | Abundance | Notes | Images |
| Thrissops | Indeterminate | Dorset | Most common Kimmeridge clay fish, known from several complete specimens | Housed at the Etches Collection, discovered by Steve Etches | Complete specimen |
| Pachythrissops | Indeterminate | Dorset | | Housed at the Etches Collection, discovered by Steve Etches | |
| Allothrissops | Indeterminate | Dorset | | Housed at the Etches Collection, discovered by Steve Etches | |
| Chondrostei | Indeterminate | Dorset | One specimen, a fin | Housed at the Etches Collection, discovered by Steve Etches | |
| Lepidotes | Indeterminate | Dorset | | Housed at the Etches Collection, discovered by Steve Etches | |
| Gyrodus | Indeterminate | Dorset | | Housed at the Etches Collection, discovered by Steve Etches | |
| Caturus | Indeterminate | Dorset | | Housed at the Etches Collection, discovered by Steve Etches | Caturus furcatus |
| Aspidorhynchus | Indeterminate | Dorset | | Housed at the Etches Collection, discovered by Steve Etches | |
| Hypsocormus | H.tenuirostris | Dorset | Rare | Housed at the Etches Collection, discovered by Steve Etches | |
| Pachycormus | Indeterminate | Dorset | Rare | Housed at the Etches Collection, discovered by Steve Etches | |
| Eurycormus | Indeterminate | Dorset | Rare, one complete specimen | Housed at the Etches Collection, discovered by Steve Etches | |
| Leptolepidae | Indeterminate | Dorset | Fairly common, multiple near complete specimens. | Housed at the Etches Collection, discovered by Steve Etches | |

### Lobe-finned fish

Lobe-finned fishes of the Kimmeridge clay Formation :
| Genus | Species | Location | Stratigraphic Position | Abundance | Notes | Images |
| Holophagus | Indeterminate | Dorset | | One specimen, cranial material | Coelacanth. Housed at the Etches Collection, discovered by Steve Etches. More than 2 metres long | |

### Cartilaginous fish

Cartilaginous fishes of the Kimmeridge clay Formation :
| Genus | Species | Location | Stratigraphic Position | Abundance | Notes |
| Asteracanthus | Indeterminate | Dorset | | Known from many dorsal spines | Housed at the Etches Collection, discovered by Steve Etches |
| Chimaera | Indeterminate | Dorset | | Known from many dorsal spines | Housed at the Etches Collection, discovered by Steve Etches |
| Hybodus | Indeterminate | Dorset | | Known from many dorsal spines, perhaps a complete head | Housed at the Etches Collection, discovered by Steve Etches |
| Ischyodus | Indeterminate | Dorset | | One specimen | Housed at the Etches Collection, discovered by Steve Etches |
| Rhinobatidae | Indeterminate | Dorset | | Known from a complete specimen, and other isolated remains | Housed at the Etches Collection, discovered by Steve Etches |
| Kimmerobatis | K. etchesi | Dorset | Encombe (holotype) and Rope Lake Head (paratype) | Known from two partial skeletons | A spathobatid ray; housed at the Etches Collection, discovered by Steve Etches |
| Durnonovariaodus | D. maiseyi | Dorset | Pectinatites pectinatus ammonite zone | One partial skeleton | A hybodontid |

### Turtles

Turtles of the Kimmeridge clay Formation :
| Genus | Species | Location | Abundance | Notes |
| Craspedochelys | C. passmorei | Swindon | "NHMUK R5871 (holotype), subcomplete shell with associated postcranial remains, including parts of the girdles, the left humerus, and partial cervical vertebrae" | Thalassochelydian sea turtle |
| Achelonia | A. formosa | Ely, Cambridgeshire | "CAMSM J29898 to CAMSM J29955 (holotype), a partial, disarticulated skeleton" | Thalassochelydian sea turtle, formerly considered the distinct species "Enaliochelys chelonia" |
| Pelobatochelys | P. blakii | Weymouth | Carapace fragments | Thalassochelydian sea turtle |
| Plesiochelys | P. etalloni | | "basicranium with partial otic chambers and fragment of the right maxilla" | Thalassochelydian sea turtle |
| Thalassemys | T. bruntrutana, T. hugii | Isle of Purbeck (bruntrutana), Abingdon, Oxfordshire (hugii) | "A partial carapace and associated limb and girdle elements (NHMUK R8699)" (Purbeck) "A large shell (OUMNH J.66966)" (Oxfordshire) | Thalassochelydian sea turtle |
| Tropidemys | P. langii | Weymouth | "NHMUK OR44178b, an isolated neural; NHMUK OR45920, right costals 1–3; NHMUK OR45921, a left first costal; NHMUK R2733, a left fourth costal" | Thalassochelydian sea turtle |

### Archosaurs
#### Thalattosuchians

| Genus | Species | Notes | Images |
| Bathysuchus | B. megarhinus | A pelagic teleosaurid. | Cricosaurus Dakosaurus Plesiosuchus Torvoneustes |
| Cricosaurus | C. gracilis | A metriorhynchine metriorhynchid | Cricosaurus Dakosaurus Plesiosuchus Torvoneustes |
| Dakosaurus | D. maximus | A geosaurine metriorhynchid | Cricosaurus Dakosaurus Plesiosuchus Torvoneustes |
| Metriorhynchus | M. brevirostris | A metriorhynchine metriorhynchid | Cricosaurus Dakosaurus Plesiosuchus Torvoneustes |
| Plesiosuchus | P. manseli | A geosaurine metriorhynchid | Cricosaurus Dakosaurus Plesiosuchus Torvoneustes |
| Torvoneustes | T. carpenteri | A geosaurine metriorhynchid | Cricosaurus Dakosaurus Plesiosuchus Torvoneustes |
| Torvoneustes | T. coryphaeus | A geosaurine metriorhynchid | Cricosaurus Dakosaurus Plesiosuchus Torvoneustes |

#### Ornithischians

Indeterminate ankylosaur osteoderms have been found in Wiltshire, England. Indeterminate stegosaurid remains have been found in Dorset and Wiltshire, England.
| Genus | Species | Location | Abundance | Notes | Images |
| Cumnoria | C. prestwichii | Oxfordshire | "Fragmentary skull and skeleton." | Iguanodontian | CumnoriaDacentrurus |
| Dacentrurus | D. armatus | Cambridgeshire Dorset Wiltshire | vertebrae, a massive right femur (thigh bone), ribs and a near complete pelvis. | Stegosaur. Wiltshire remains include specimens previously referred to Omosaurus armatus and O. hastiger. | CumnoriaDacentrurus |
| Ornithopoda | Indeterminate | Dorset? | | Kimmeridge clay remains considered to represent a possible close relative of Bugenasaura are now regarded as the remains of an indeterminate euornithopod.(The specimen may have had its locality and horizon mislabelled.) | CumnoriaDacentrurus |
| Omosaurus | O.armatus | Wiltshire | Reclassified as Dacentrurus armatus because the generic name Omosaurus was preoccupied. | | CumnoriaDacentrurus |
| Omosaurus | O. hastiger | Wiltshire | | | CumnoriaDacentrurus |

#### Saurischians

Indeterminate ornithomimmid remains have been found in Dorset, England. An undescribed theropod genus was found in Dorset.
| Genus | Species | Location | Material | Notes | Images |
| Bothriospondylus | B. suffosus | Wiltshire | "[Seven] dorsal and sacral centra." | Considered a nomen dubium. | Juratyrant |
| Cetiosaurus | C. humerocristatus | Dorset | | Now Duriatitan. | Juratyrant |
| Cetiosaurus | Indeterminate | Oxfordshire | | Remains previously referred to an indeterminate species of Cetiosaurus are now regarded as indeterminate sauropod material. | Juratyrant |
| Duriatitan | D. humerocristatus | Dorset | Humerus | A titanosauriform | Juratyrant |
| Gigantosaurus | G. megalonyx | Cambridgeshire | | Remains previously referred to Gigantosaurus megalonyx are now regarded as indeterminate sauropod material. | Juratyrant |
| "Ischyrosaurus" | I. manseli | Oxfordshire | "Humerus." | Remains previously referred to Ischyrosaurus manseli are now regarded as indeterminate sauropod material. | Juratyrant |
| Juratyrant | J. langhami | Dorset | Partial skeleton | A primitive tyrannosaur | Juratyrant |
| Torvosaurus | Indeterminate | Swindon, Dorset | Tibia (OUMNH J.29886) and maxilla fragment, collected separately | A megalosaurid | Juratyrant |
| Theropoda | Indeterminate | Wiltshire Dorset | A tooth from Foxhangers, Wiltshire (NHMUK 46388), phalanges from an unspecified locality in Wiltshire (DZSWS 3009), and a proximal caudal vertebra from Shotover, Oxfordshire (OUMNH J.47134). | Remains previously referred to Megalosaurus are now regarded as indeterminate theropod material. | Juratyrant |
| Sauropoda | Indeterminate | Oxfordshire Cambridgeshire Norfolk | | Remains previously attributed to one or more indeterminate species of Ornithopsis (incl. O. leedsii) are now regarded as possible indeterminate sauropod material. | Juratyrant |

#### Pterosaurs

| Genus | Species | Location | Material | Notes | Images |
| Cuspicephalus | C. scarfi | Dorset | Partial Skull | Missing Crest, lower jaw and dentition | Cuspicephalus Rhamphorhynchus |
| Germanodactylus | indeterminate | Charnel, Dorset | | May be a non-pterodactyloid monofenestratan instead | Cuspicephalus Rhamphorhynchus |
| Rhamphorhynchus | R. etchesi | Encombe, Dorset | | | Cuspicephalus Rhamphorhynchus |
| Ctenochasmatoidea | indeterminate | Abingdon, Oxfordshire | Left first wing finger phalanx | | Cuspicephalus Rhamphorhynchus |

### Plesiosaurs

| Genus | Species | Abundance | Notes | Images |
| Bathyspondylus | B. swindoniensis | | Plesiosaur of unknown affinities | Kimmerosaurus Pliosaurus brachydeirus |
| Colymbosaurus | C. megadeirus | | A cryptoclidid | Kimmerosaurus Pliosaurus brachydeirus |
| Colymbosaurus | C. trochantericus | | Nomen dubium | Kimmerosaurus Pliosaurus brachydeirus |
| Kimmerosaurus | K. langhami | | A cryptoclidid | Kimmerosaurus Pliosaurus brachydeirus |
| Plesiosaurus | "P." manseli | | Distinct from Colymbosaurus. | Kimmerosaurus Pliosaurus brachydeirus |
| Pliosaurus | P. brachydeirus | | A thalassophonean pliosaurid | Kimmerosaurus Pliosaurus brachydeirus |
| Pliosaurus | P. brachyspondylus | | Nomen dubium | Kimmerosaurus Pliosaurus brachydeirus |
| Pliosaurus | P. carpenteri | | A thalassophonean pliosaurid | Kimmerosaurus Pliosaurus brachydeirus |
| Pliosaurus | P. kevani | | A thalassophonean pliosaurid | Kimmerosaurus Pliosaurus brachydeirus |
| Pliosaurus | P. portentificus | | A nomen dubium | Kimmerosaurus Pliosaurus brachydeirus |
| Pliosaurus | P. ?rossicus | | A thalassophonean pliosaurid; taxonomic identification of specimens tentative | Kimmerosaurus Pliosaurus brachydeirus |
| Pliosaurus | P. westburyensis | | A thalassophonean pliosaurid | Kimmerosaurus Pliosaurus brachydeirus |
| Pliosaurus | P. sp. 1 | Partial skeleton, CAMSM J.35991 | A thalassophonean pliosaurid; previously assigned to the nomen dubium P. brachyspondylus | Kimmerosaurus Pliosaurus brachydeirus |
| Pliosaurus | P. sp. 2 | Mandible, NHMUK PV OR 39362 | A thalassophonean pliosaurid; previously assigned to the nomen dubium P. macromerus | Kimmerosaurus Pliosaurus brachydeirus |
| Spitrasaurus | Indeterminate | | | Kimmerosaurus Pliosaurus brachydeirus |

### Ichthyosaurs

| Genus | Species | Location | Stratigraphic Position | Notes | Images |
| Brachypterygius | B.extremus | Dorset | | | Brachypterygius Grendelius Nannopterygius Thalassodraco Ophthalmosaurus |
| Grendelius | G.mordax | Dorset | | | Brachypterygius Grendelius Nannopterygius Thalassodraco Ophthalmosaurus |
| Ichthyosauridae | Indeterminate | Dorset | | Giant, near complete specimen. Proposed to have been 6 metres long when complete. Housed at the Etches Collection in Dorset. | Brachypterygius Grendelius Nannopterygius Thalassodraco Ophthalmosaurus |
| Macropterygius | M.trigonus | Dorset | | Nomen dubium - classified by a single vertebra | Brachypterygius Grendelius Nannopterygius Thalassodraco Ophthalmosaurus |
| Nannopterygius | N.enthekiodon | Dorset | | | Brachypterygius Grendelius Nannopterygius Thalassodraco Ophthalmosaurus |
| Thalassodraco | T. etchesi | Dorset | The Pectinatites pectinatus ammonite zone | | Brachypterygius Grendelius Nannopterygius Thalassodraco Ophthalmosaurus |
| Ophthalmosaurus | Indeterminate | Dorset | | | Brachypterygius Grendelius Nannopterygius Thalassodraco Ophthalmosaurus |

## Invertebrates

The invertebrate fauna of the Kimmeridge Clay includes:
* Mollusca:
** Cardium striatulum
** Ostrea deltoidea
** Gryphaea (Exogyra) virgula
** Trigonellites
** Belemnotheutis
** Etchesia
* Arthropoda:
** Phlyctosoma sp.
** Eryma sp.
** Magila latimana
** Mecochirus sp.
** Archaeolepas redtenbacheri