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, thalattosuchians, 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 Kimmeridge Clay crops out in an somewhat interrupted band from Dorset to Lincolnshire. Further northeast, beneath the North Sea, where it attains a huge thickness, it is the source for much of the North Sea Oil. The characteristics that make this formation a rich oil source are present in Buckinghamshire too - a high fossil organic component, although it has not been subjected to sufficient temperature to yield any hydrocarbon.
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
Fauna uncovered from the Kimmeridge Clay include:Weishampel, David B; et al. (2004). "Dinosaur distribution (Late Jurassic, Europe)." In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. Pp. 545–549. .
Ray-finned fish Ray-finned fishes of the Kimmeridge clay Formation Genus Species Location Stratigraphic Position Abundance Notes ImagesThrissopsEtches, S, Clarke, J. (2010). Life in Jurassic seas. Dorset, Dorchester: Epic Creative Print.T. kimmeridgensisIsle of Purbeck, DorsetMost common Kimmeridge clay fish, known from several complete specimensHoused at the Etches Collection, discovered by Steve Etches. Most prominently distinguished from other species of the Genus by the irregular size of its dentary teeth.PachythrissopsIndeterminateDorsetHoused at the Etches Collection, discovered by Steve EtchesAllothrissopsIndeterminateDorsetHoused at the Etches Collection, discovered by Steve EtchesChondrosteiIndeterminateDorsetOne specimen, a finHoused at the Etches Collection, discovered by Steve EtchesLepidotesIndeterminateDorsetHoused at the Etches Collection, discovered by Steve Etches GyrodusIndeterminateDorsetHoused at the Etches Collection, discovered by Steve EtchesCaturusIndeterminateDorsetHoused at the Etches Collection, discovered by Steve EtchesAspidorhynchusIndeterminateDorsetHoused at the Etches Collection, discovered by Steve EtchesHypsocormusH.tenuirostrisDorsetRareHoused at the Etches Collection, discovered by Steve EtchesPachycormusIndeterminateDorsetRareHoused at the Etches Collection, discovered by Steve EtchesEurycormusIndeterminateDorsetRare, one complete specimenHoused at the Etches Collection, discovered by Steve EtchesLeptolepidaeIndeterminateDorsetFairly 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 ImagesHolophagusIndeterminateDorsetOne specimen, cranial materialCoelacanth. 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 ImagesAsteracanthusIndeterminateDorsetKnown from many dorsal spinesHoused at the Etches Collection, discovered by Steve EtchesChimaeraIndeterminateKnown from many dorsal spinesHoused at the Etches Collection, discovered by Steve EtchesHybodusIndeterminateKnown from many dorsal spines, perhaps a complete headHoused at the Etches Collection, discovered by Steve EtchesIschyodusIndeterminateOne specimenHoused at the Etches Collection, discovered by Steve EtchesRhinobatidaeIndeterminateKnown from a complete specimen, and other isolated remainsHoused at the Etches Collection, discovered by Steve EtchesKimmerobatisK. etchesiEncombe (holotype) and Rope Lake Head (paratype)Known from two partial skeletonsAn asterodermid ray; housed at the Etches Collection, discovered by Steve EtchesDurnonovariaodus D. maiseyiPectinatites pectinatus ammonite zoneOne partial skeletonA hybodontid
Turtles Turtles of the Kimmeridge clay Formation Genus Species Location Stratigraphic Position Abundance Notes ImagesCraspedochelysC. passmoreiSwindon"NHMUK R5871 (holotype), subcomplete shell with associated postcranial remains, including parts of the girdles, the left humerus, and partial cervical vertebrae"Thalassochelydian sea turtleAcheloniaA. formosaEly, Cambridgeshire"CAMSM J29898 to CAMSM J29955 (holotype), a partial, disarticulated skeleton"Thalassochelydian sea turtle, formerly considered the distinct species "Enaliochelys chelonia"PelobatochelysP. blakiiWeymouthCarapace fragmentsThalassochelydian sea turtlePlesiochelysP. etalloni"basicranium with partial otic chambers and fragment of the right maxilla"Thalassochelydian sea turtleThalassemys T. bruntrutana, T. hugiiIsle 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 turtleTropidemysP. langiiWeymouth"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 Location Member Abundance Notes ImagesBathysuchusB. megarhinusA pelagic teleosaurid.CricosaurusC. gracilisA metriorhynchine metriorhynchidDakosaurusD. maximusA geosaurine metriorhynchidMetriorhynchusM. brevirostrisA metriorhynchine metriorhynchidPlesiosuchusP. manseliA geosaurine metriorhynchid Torvoneustes T. carpenteriA geosaurine metriorhynchidT. coryphaeusA geosaurine metriorhynchidMachimosaurusM. spTeleosauroid.
Ornithischians Indeterminate ankylosaur osteoderms have been found in Wiltshire, England. Indeterminate stegosaurid remains have been found in Dorset and Wiltshire, England.
Genus Species Location Member Abundance Notes ImagesCumnoriaC. prestwichii Oxfordshire"Fragmentary skull and skeleton.""Table 19.1," in Weishampel, et al. (2004). Page 415.IguanodontianDacentrurusD. armatus Cambridgeshire Dorset Wiltshirevertebrae, 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.OrnithopodaIndeterminate 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.)OmosaurusO.armatus WiltshireReclassified as Dacentrurus armatus because the generic name Omosaurus was preoccupied.O. hastiger Wiltshire
Saurischians Indeterminate ornithomimmid remains have been found in Dorset, England. An undescribed theropod genus was found in Dorset. Genus Species Location Stratigraphic position Material Notes ImagesBothriospondylusB. suffosus Wiltshire"[Seven] dorsal and sacral centra.""Table 13.1," in Weishampel, et al. (2004). Page 270.Considered a nomen dubium.CetiosaurusC. humerocristatus DorsetNow Duriatitan.Indeterminate OxfordshireRemains previously referred to an indeterminate species of Cetiosaurus are now regarded as indeterminate sauropod material.DuriatitanD. humerocristatus DorsetHumerus"Table 13.1," in Weishampel, et al. (2004). Page 267.A titanosauriformGigantosaurusG. megalonyx CambridgeshireRemains previously referred to Gigantosaurus megalonyx are now regarded as indeterminate sauropod material."Ischyrosaurus"I. manseli Oxfordshire"Humerus.""Table 13.1," in Weishampel, et al. (2004). Page 271.Remains previously referred to Ischyrosaurus manseli are now regarded as indeterminate sauropod material.JuratyrantJ. langhami DorsetPartial skeletonA primitive tyrannosaurTorvosaurusIndeterminate Swindon, DorsetTibia (OUMNH J.29886) and maxilla fragment, collected separatelyA megalosauridTheropodaIndeterminate Wiltshire DorsetA 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.SauropodaIndeterminate Oxfordshire Cambridgeshire NorfolkRemains previously attributed to one or more indeterminate species of Ornithopsis (incl. O. leedsii) are now regarded as possible indeterminate sauropod material.
Pterosaurs
GenusSpeciesLocationMaterialNotesImages Cuspicephalus C. scarfi Dorset Partial Skull Missing Crest, lower jaw and dentition Germanodactylus indeterminate Charnel, Dorset May be a non-pterodactyloid monofenestratan instead Rhamphorhynchus R. etchesi Encombe, Dorset Ctenochasmatoidea indeterminate Abingdon, Oxfordshire Left first wing finger phalanx
Plesiosaurs Genus Species Location Member Abundance Notes ImagesBathyspondylusB. swindoniensisPlesiosaur of unknown affinitiesColymbosaurusC. megadeirusA cryptoclididC. trochantericusNomen dubiumKimmerosaurusK. langhamiA cryptoclididPlesiosaurus"P." manseliDistinct from Colymbosaurus.Pliosaurus Low resolution pdf High resolution pdf P. brachydeirusA thalassophonean pliosaurid P. brachyspondylus Nomen dubiumP. carpenteriA thalassophonean pliosauridP. kevaniA thalassophonean pliosaurid P. portentificus A nomen dubiumP. ?rossicusA thalassophonean pliosaurid; taxonomic identification of specimens tentativeP. westburyensisA thalassophonean pliosauridP. sp. 1Partial skeleton, CAMSM J.35991A thalassophonean pliosaurid; previously assigned to the nomen dubium P. brachyspondylusP. sp. 2Mandible, NHMUK PV OR 39362A thalassophonean pliosaurid; previously assigned to the nomen dubium P. macromerusSpitrasaurusIndeterminate
Ichthyosaurs Genus Species Location Stratigraphic Position Abundance Notes ImagesBrachypterygiusB.extremusDorset GrendeliusG.mordaxDorsetIchthyosauridaeIndeterminateDorsetGiant, near complete specimen. Proposed to have been 6 metres long when complete. Housed at the Etches Collection in Dorset. Macropterygius M.trigonus Dorset Nomen dubium - classified by a single vertebraNannopterygiusN.enthekiodonDorsetThalassodracoT. etchesiDorsetThe Pectinatites pectinatus ammonite zone OphthalmosaurusIndeterminateDorset
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
See also List of dinosaur-bearing rock formations
References
Bibliography Galton, P.M. 1999. Cranial anatomy of the hypsilophodontid dinosaur Bugenasaura infernalis (Ornithischia: Ornithopoda) from the Upper Cretaceous of North America. Revue Pale´obiologie, 18, 517–534.
Further reading