West, Ian M. 2016. Kimmeridge Clay Fossils; Geology of the Wessex Coast, southern England. Internet webpage: www.southampton.ac.uk/~imw/kimfoss.htm, Version: 26th January 2016.
Fossils of the Kimmeridge Clay, Upper Jurassic, Dorset

Ian West,

Romsey, Hampshire
and Visiting Scientist at:
Faculty of Natural and Environmental Science,
Southampton University,

Webpage hosted by courtesy of iSolutions, Southampton University

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Crushed ammonite under water

Giant Pliosaur tooth

Brachiosaurus



Other Kimmeridge Field Guides

Kimmeridge and Kimmeridge Bay - Introduction
Kimmeridge - Fossils
Kimmeridge - Kimmeridge Bay and Kimmeridge Coast Introduction
Kimmeridge - West of Kimmeridge Bay, including Broad Bench, Hobarrow Bay and Brandy Bay
Kimmeridge - East - Hen Cliff, Yellow Ledge and Cuddle
Kimmeridge - Blackstone, Oil Shale at Clavell's Hard
Kimmeridge - Burning Beach, Burning Cliffs
Kimmeridge - Rope Lake Head to Freshwater Steps
Kimmeridge - Egmont Bight to Chapman's Pool
Kimmeridge - Bibliography - Start
Kimmeridge - Bibliography Continued

(You can download this educational site to SurfOffline, WebCopier or similar software to keep a safe permanent offline copy, but note that at present there is periodic updating of the live version.)

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INTRODUCTION:

Kimmeridge Clay Fossils - Introduction

The Kimmeridge Clay contains a remarkable range of fossils including occasional bones of dinosaurs, ichthyosaurs, plesiosaurs and pterosaurs and many invertebrate fossils. It is an important formation from a palaeontological point of view and the cliffs here have been yielding remarkable finds for almost two centuries.

On a brief visit crushed ammonites are conspicuous. These are common in the shales of the Kimmeridge Clay. Here is an example in a shale ledge on the shore east of Clavell's Hard. Uncrushed ammonites also occur in places, usually where there are early septarian nodules which have been lithified before compaction and thus retained the ammonite in original shape. Chapmans Pool, with the Rotunda Nodules, is the easiest place for finding such specimens, although I have found a rare specimen loose on the shore between Rope Lake Head and Freshwater Steps. Ammonites are not usually found uncrushed in Kimmeridge Bay though.

Some various fossil groups are discussed below with some illustrations. The discussion here is brief and only a selection of interesting fossil remains are considered. References are given which should be consulted for more detail and for faunal lists. More fossil illustrations and descriptions will be added here from time to time.

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INTRODUCTION:

The Steve Etches Kimmeridge Fossil Collection

The most important collection of Kimmeridge Clay fossils is that of Steve Etches, the well-known collector who lives at Kimmeridge. Part of his collection is on display in the Heritage Centre at Lulworth Cove. There are plans to display more of it in the future in the Kimmeridge area. It is a magnificent collection of vertebrate remains, including those of ichthyosaurs, plesiosaurs, dinosaurs, pterosaurs and fish. In addition there are various very well preserved ammonites and other cephalopods.

Steve Etches the well-known collector and palaeontologist of the Kimmeridge Clay, Dorset, UK

Steve Etches with his Kimmeridge Clay fossil collection, including the skull of a marine crocodile

Saurian jaws and teeth from the Kimmeridge Clay, Dorset, Steve Etches Collection

Catalogue of the Steve Etches Kimmeridge Clay collection, Dorset

Steve Etches searches the cliffs regularly and has discovered and prepared numerous superb specimens. See the Steve Etches Catalogue, details of which are given below. See also de Bruxelles (1999) (above) for an article in The Times about Steve Etches.

Etches , S. and Clarke, J. 1999 (with updates). Steve Etches Kimmeridge Collection: Illustrated Catalogue. (by Steve Etches and Jane Clarke). The catalogue is in the form of a ring-binder so that pages can be added. It is an assemblage of A4 pages with monochrome photographs and brief captions. It has been privately published by Jane Clarke (jane@geoden.demon.co.uk)
This catalogue illustrates 370 of the most important of the 1,561 fossil specimens contained in the Steve Etches Kimmeridge Collection. This impressive collection is housed in a private museum and it may be viewed by appointment (the telephone number is given in the catalogue). All the specimens have been collected since 1981, the bulk coming from the Kimmeridge Bay area on the Dorset coast. Other material has come from Oday Common, Abingdon, Oxfordshire, the Blue Circle Cement Quarry, Westbury Wiltshire, the Black Isle, Ross and Cromarty, Scotland and Cap de la Havre, Normandy France. The many photographs include those of ammonite, ammonite eggs, bivalves, lobsters, fish, ichthyosaurs, plesiosaurs, pliosaurs and pterosaurs. An interesting feature are the predatory toothmarks which Steve Etches has found in some of the bones. Genera illustrated include Aspidoceras, Aulacostephanus, Crussoliceras, Pectinatites, Pictonia, Eurycormis, Caturus, Trachyteuthis, Allothrissops, Geosaurus, Metriorhynchus, Eryma, Goniomya, Leptolepis, Hypsocormus, Gyrodus and various genera of marine saurians.

The Steve Etches collection is marvellous but not yet fully on public display. The illustrations of fossils from the Kimmeridge Clay given below are not from this collection and mostly of only text-book quality. They are only intended for practical use by the geologist visiting Kimmeridge and not for serious palaeontological purposes. It is hoped that they prove to be convenient illustrations, giving meaning to the names which are used in the stratigraphical text of the various Kimmeridge webpages, provided on this site. They are also intended for practical field use.

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PLESIOSAURS

Plesiosaur humerus

This humerus of a plesiosaur - probably Cryptoclidus was found on the seafloor east of the Isle of Porland by an amateur diver. It had presumably been washed out of the Kimmeridge Clay which occupies a large area of the seafloor between Kimmeridge and Portland. It is shown here on the deck of a boat with a mobile phone for scale. I am grateful to former Southampton University students Jack Armitage for sending me this and to Darren Naish for identification. Vertebrate remains, particular vertebrae of ichthyosaurs, are also found by divers on the Kimmeridge Clay outcrop on the seafloor southwest of the Chesil Beach.

Mansell-Pleydell (1888) referred to the discovery of Plesiosaurus brachistospondlylus Hulke, from the Kimmeridge Clay of Kimmeridge. There were five middle dorsal vertebrae, portions of several ribs and a phalangeal bone. This was referred by Delair (1959) to ?Colymbosaurus brachistospondylus, (Hulke). He commented that it differs from all other Kimmeridgian Plesiosaurs in the extreme shortness of its centra. Plesiosaurus plicatus Phillips, was also found in the Kimmeridge Clay of Weymouth.

Delair (1959) discussed the occurrence of Muraenosaurus truncatus, (Lydekker, ex Owen). This was originally known from the Kimmeridge Clay of Oxfordshire and has been found in the Kimmeridge Clay at or near Weymouth, on the Isle of Portland and at Kimmeridge Bay. Cervical and dorsal vertebrae are relatively common, some with centra with transverse diameters larger than 7cm. ?Colymbosaurus trochanterius, (Owen) has been found as bone fragments in the Kimmeridge Clay of Kimmeridge. Saurian bones of ?Colymbosaurus cf. trochanterius, (Owen) have been discovered at Kimmeridge and Kimmeridge Bay.

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PLIOSAURS

Pliosaurus macromerus skull

Pliosaurus macromerus skull -details

Giant Pliosaur tooth from the Kimmeridge Clay

Kimmeridge is notable for its remains of pliosaurs. Mansel-Pleydell (1888) commented succinctly on these reptiles.

"Genus - Pliosaurus. This genus is closely allied to Plesiosaurus, but differs in its enormous head and extremely short neck. It has a limited vertical range in Great Britain, from the Oxford Clay to the Portland Beds inclusive. Its remains, however, have been found in the Cretaceous beds of North America... It can be identified better by its trihedral-shaped tooth than by any other character, so similar is it to Plesiosaurus. The cervical vertebrae increase in breadth and depth as they recede from the head, and assume the Plesiosaurian type."

Some notes on Kimmeridgian Pliosaurs follow:

Pliosaurus macromerus, Phillips

Remains of a great Pliosaur were found by Mansel-Pleydell in the Kimmeridge Clay of Kimmeridge in the 1860s. The discovery of a gigantic tooth 0.305m (12 inches) long and shown here caused Mansel-Pleydell (1888) to comment on the size and destructive power of the jaw. The skull, also figured above, was then found, also at Kimmeridge. It was described by Owen (1861-1869) as Pliosaurus grandis. Delair (1959) considered that this should be classified as Pliosaurus macromerus and that this was the largest described species of Pliosaurus.

The Pliosaur is known from bones found in the Kimmeridge Clay of Swindon, Wiltshire, Shotover, Oxfordshire and Sandford. It is also known from the Upper Jurassic of Germany. According to Delair (1959) , there is preserved in the Dorset County Museum, Dorchester, one of the largest and most complete Pliosaurian limbs ever discovered (G 123 D.C.M). It has a total length of 2.01m (6 feet, 7 inches). These remains, consisting of a femur and the nearly entire set of phalangeal bones, were found in the Kimmeridge Clay of Kimmeridge Bay by that great discoverer Mansel-Pleydell, again. Two incomplete, fractured lower jaws were found in 1912 by Miss C. Ouless in the Kimmeridge Clay of Ringstead. The jaws as preserved measure 1.06m (3 feet, 6 inches) but originally must have been some some centimetres longer Delair (1959) , Apart from teeth from Kimmeridge there are vertebrae from the Kimmeridge Clay of Gillingham, the Isle of Portland, Kimmeridge Bay and Motcombe near Shaftesbury. No complete skeleton has been found.

Pliosaurus brachydeirus, (Owen).

Teeth and vertebrae from have been found in the Kimmeridge Clay of Weymouth, Osmington Mills and the Isle of Portland (Delair, 1959).

Pliosaurus brachyspondylus, (Owen). Mansell-Pleydell referred to the finding of what was then termed Plesiosaurus brachyspondylus Owen, in the Kimmeridge Clay in the neighbourhood of Weymouth. It consisted of remains of vertebrae only. Delair referred to this species as Pliosaurus brachyspondlylus. Three anterior dorsal vertebrae have been found in the Kimmeridge Clay of Kimmeridge Bay, but Delair said that these are the only known Dorset bones of this species. The Plesiosaur/Pliosaur classification seems complicated and the specialist needs to consult, amongst others, Delair's and Mansel-Pleydell's papers. The species is also known from the Kimmeridge Clay of Heddington (Headington) pits, near Oxford.

Other Pliosaur Remains

Bones , including large ribs have been found at Kimmeridge Bay (and "Gaulters Bay"), Osmington, Ringstead Bay, Weymouth, Stoke Wake and Hazelbury Bryan. Vertebrae have been found in the Kimmeridge Clay of Shotover, Oxfordshire. A Pliosaur femur from the Kimmeridge Clay of Gillingham was presented to the Natural History Museum, London in 1927 by B. Pope-Bartlett, Esq. (Delair, 1959).

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The Weymouth Bay Pliosaur - 2013.

The remains of a very large Pliosaur with a jaw 2.4m long have been found in the Kimmeridge Clay in Weymouth Bay

Go to
Dorset County Museum webpage: The World's Biggest Bite - the Weymouth Bay Pliosaur.

"The giant jaws of a huge marine reptile are now on permanent display at the Dorset County Museum following its formal unveiling by Sir David Attenborough. Dating back around 155 million years, the pliosaur skull was discovered on the nearby Jurassic Coast World Heritage Site, and is one of the largest and best preserved fossils of its kind ever found. Belonging to a creature up to 18m in length, the skull is a staggering 2.4 m long and is believed to have possessed the biggest bite of all time powerful enough to break a small car in half."

For more regarding this pliosaur:

see:

BBC News: Kevan Sheehan: Dorset Man names New Pliosaur.

Extracts from the article (see the full version online):

A 2.4m-long "sea monster" skull recovered in Dorset has been identified as a new species. The 155-million-year-old fossil was discovered by collector Kevan Sheehan in 2003 in cliffs near Weymouth. It was named in his honour as Pliosaurus kevani, in the online journal PLoS One.

Two pliosaurs unearthed in Wiltshire have also been named as new species... The Dorset specimen, held at the Dorset County Museum, is thought to belong to one of the biggest pliosaurs ever found. "I was so lucky - I was sitting on the beach, and saw three pieces just lying within a few inches of each other," said Mr Sheehan, a retired cafe owner from Osmington, near Weymouth. "I thought it was fossilised wood and when I found the skull - it was about 70 to 80 kgs - I buried it so that I could get a friend to come and help me dig it up and carry it down to his tender. "Then over several years, I'd go back every year and find a new piece. I'm a beach magpie." Pliosaurs were the top predators of the oceans. The fossil was purchased for 20,000 by the museum, with half of the money going to the collector and half to the landowner....

Two other new species of pliosaurus were also named in the paper, both found in clay pits near Westbury in Wiltshire and held at Bristol City Museum and Art Gallery. Pliosaurus westburyensis was discovered in the 1980s whilst Pliosaurus carpenteri has been named in honour of Simon Carpenter, who unearthed his 35ft (11m) long, 140 million-year-old "beast" in 1994.

See the paper by Benson et. al. (2013) on Jurassic Pliosaurs. .

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For more remarkable Pliosaur remains and even a Liopleurodon discovery (a "villain" in the BBC's Walking with Dinosaurs) see Etches and Clarke (1999).

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Footnote: Mansel-Pleydell - Kimmeridge Landowner and Saurian Hunter
John Clavell Mansel-Pleydell, Esq.of Whatcombe, B.A., J.P. and D.L., F.G.S., F.L.S., President of the Dorset Natural History and Antiquarian Field Club. "Mr. Mansel-Pleydell was born in 1817, and was educated at Hazelbury Bryan under the Rev. Henry Walter, a former Professor of Natural Philosophy at Cambridge. He entered at St. John's College, Cambridge, where he took his B.A. degree in 1839 and subsequently read for the Bar. His parents resided at Smedmore [the Kimmeridge Estate] , near Corfe, until 1863, when, on the death of his mother, it passed into his own possession. Here in the parish of Kimmeridge he made one of his greatest discoveries by unearthing from a low cliff facing the sea the paddle of Pliosaurus macromerus, which is now preserved in the County Museum, Dorchester. .... I can remember with a vividness as of yesterday days spend along the sandbanks [now Sandbanks] at the mouth of Poole Harbour, around the margins of the brackish lagoon [then still with sea connection] of Littlesea, amongst the Punfield Beds of Punfield Cove near Swanage [notable fossil locality near Ballard Cliff], or the Purbecks above the cliffs of Tilly Whim and Dancing Ledge, or the Kimmeridge Clay around the shores of the bay, from which it takes its name. .. On these occasions he was quite untiring, walking fast the whole day; no rest was given for luncheon - it was eaten as we went; his mind was on the alert for everything that he saw around him; and his conversation inspiring and sparkling with numerous anecdotes, chiefly of Dorset characters and recollections... " (he did much else. He published papers on various geological subjects. He was also a botanist, magistrate, Poor Law Guardian, philanthropist, meteorologist and a Captain in the Queen's Own Dorset Yeomanry Cavalry! He died at Whatcombe in 1901 at the age of 84.). These notes are from Stuart-Gray, 1902.
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ICHTHYOSAURS:

Introduction

Ichthyosaur, skeleton to body relationship

Bones of marine reptiles of dolphin-like appearance, the ichthyosaurs ("fish lizard"), occur in the marine clay formations of Dorset. These are particularly the Liassic clays, the Oxford Clay and the Kimmeridge Clay Formations. Dorset is historically important because the very first know ichthyosaur was found at Lyme Regis in the Lias by Mary Anning when she was only 12 years old.

The Ichthyosaurs belong to the Order Ichthyopterygia. The Dorset ichthyosaurs were discussed by Delair (1960) in the third part a very useful review of Dorset fossil reptiles. Some notes here are summarised from Justin Delair's account but reference should be made to the original paper for more detailed information.

The Ichthyopterygia are a great Order of reptiles that returned to the sea and became highly adapted to it. They became aquatic during early Mesozoic times and ranged from the Trias to the end of the Cretaceous Period. Their ancestors are not known for certain but they seem to have descended from small Carboniferous reptiles which even at that time were undergoing anatomical changes necessary for an aquatic life. By the time of appearance of the first known genera it is clear that the ichthyosaurs had already had a long history. They were so adapted to the marine environment that they were unable to return to land to lay their eggs and, thus, brought forth their young alive. Fossil skeletons have shown the young ichthyosaurs emerging from the body of the mother.

Delair (1960) has provided a brief description of ichthyosaur characteristics and a simplified, modified version of this is given below.

Ichthyosaurs - Description:

These were large reptiles and quite numerous reptiles which have returned to the sea. They had a stream-lined, dolphin-like body without reptilean-type scales. They had four powerful paddle-shaped limbs. Below the strong limb bones of the humerus (upper arm) and femur (thigh bone) the paddle bones are not organised into the usual rows of finger or toe bones but arranged as a flat oar blade. There are many small subcircular or hexagonal bones, with probably not much movement between them. The skull was generally large and, unlike that of most reptles, was joined to the trunk directly and without a neck (note that old reconstructions usually showed a neck but modern ones do not). There was a powerful usually elongated snout armed with numerous powerful teeth. In the skull the nasal openings for the nostrils were placed far back and not at the end of the snout. The round cavities in the skull for the eyes, the orbits, were very large. It is interesting that the eyes were protected by a special circles of hardened (sclerotic) plates, presumably for use in deep diving. The ear-bone, the stapes, was unusually large, probably in connection with diving.

Ichthyosaur vertebrae - characteristics

The disk-like vertebrae were very numerous, and separate examples are often found as fossils on the cliffs and beaches where there is Jurassic clay. They are short disks, hollow on both sides (amphicoelous). They are normally separate from the neural arch and spine (spines of the backbone). These round disks of several centimetres diameter are quite distinctive from plesiosaur vertebrae which have neural arches and spines attached, as do those of most dinosaurs. On the cicumferances of vertebrae you can usually see the low projections where neural arches attach and ribs articulate.

A number of perfectly preserved specimens show the body outline of these reptiles. There was a large dorsal fine, but it did not have a bony support and, therefore, was at one time not known to have existed and so it is not shown in the old reconstructions. There was a large asymmetrical tail-fin, in the vertical plane, which was stiffened by a downward bend of the vertebral column (a reversed heterocercal-type fin stiffened by the posterior caudal vertebrae). Swimming seems to have been by fish-like undulations of the body and tail, with the paddle-shaped limbs being used for steering.

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ICHTHYOSAURS:

Records regarding the Kimmeridge Clay

Some records of ichthyosaur discoveries from the Kimmeridge Clay of Dorset and some other areas are given here. This is not a complete list and the publications of Delair and Etches and Clarke can provide more extensive information.

Macropterygius trigonus, (Owen)
Kimmeridge Clay of Kimmeridge Bay (vertebrae), of Weymouth and of the Isle of Portland. It also occurs in the Kimmeridge Clay of Westbrooke, in Bromham, Wiltshire and also at Stoke Wake. Also known from the Kimmeridge Clay of Boulogne and of Bavaria. For details see Delair (1960).

Macropterygius dilatatus, (Phillips)
Vertebrae from the Kimmeridge Clay of Kimmeridge. Skull with vertebrae and other bones from the Kimmeridge Clay of Swindon. For details see Delair (1960).

?Macropterygius ovalis, (Phillips)
A dorsal vertebra from the Kimmeridge Clay of Kimmeridge with a note that it came from a bed of "Bituminous Schist" [i.e. - oil shale] . Also know from a vertebra from the Kimmeridge Clay of Weymouth and from Swindon (Wiltshire) and Shotover (Oxfordshire). This was a large species. For details see Delair (1960).

?Macropterygius thyreospondylus, (Owen)
Large ichthyosaur. Six caudal vertebrae from the Kimmeridge Clay of Weymouth. A posterior caudal vertebra from the Kimmeridge Clay of the Isle of Portland. For details see Delair (1960). A very large vertebral centrum probably of this ichthyosaur and from the Kimmeridge Clay of Dorset was later reported by Delair (1986).

Macropterygius sp.
Several vertebrae in the Dorset County Museum, one large example from the Kimmeridge Clay of Sandsfoot. A number of large vertebrae from the Kimmeridge Clay of Ringstead Bay, found by Miss C. Ouless, are also in the Dorset County Museum. Also from the Kimmeridge Clay of Gillingham. For details see Delair (1960).

Indeterminate
Teeth, vertebrae, mandibular bones, scapulae etc of ichthyosaurs from the Kimmeridge Clay of Weymouth. For details see Delair (1960).

Ophthalmosaurus pleydelli Lydekker
Humerus from the Kimmeridge Clay of Gillingham. For details see Delair (1960).

Ophthalmosaurus sp

Ichtyosaur bones

A series of vertebrae and associated bones in matrix were found in the Upper Kimmeridge Clay of Freshwater Bay by Dr Dru Drury, and were excavated by him and Captain G. Fenwick-Owen, by permission of Lady Hamilton Russell (Delair, 1960).

Not far away at Rope Lake Head, in 1955, I was with Mr G. Symes of Bournemouth when he discovered ichthyosaur vertebrae, of Ophthalmosaurus a short distance above the beach. We found other bones and excavated as much as we could. A sketch of these which I made at the time is reproduced here. The bones were at the promontory itself and were found in what was then listed by Arkell (1947) as grandis zone, 0.76m (2 feet, 6 inches) below the base of the wheatleyensis subzone. In modern terminology this is within the hudlestoni zone. The site was a few metres east of the most extreme southern point of the cliff and just above a ledge forming a small platform near the base of the cliff. It was from time to time covered by an apron of shale scree and it was not possible to excavate safely far into the cliff. The skull was missing but a number of other bones including part of the verterbral column, numerous ribs and some limb bones were preserved. The central part of the mass of bones was pyritised, and where this had happened the vertebrae were badly distorted. In other words they had been pyritised under burial and during compaction. Some of the bones are at Bournemouth School and some at Southampton University. Delair (1986) has a published a short account of these bones in a survey of little-known ichthyosaurs from Dorset.

Brachypterygius extremus, Boulanger
A very large ichthyosaur, although only known from bones of the anterior limb Delair (1960) . The specimen is a right anterior paddle acquired by the British Museum (Natural History), now the Natural History Museum, London, from Harold Landsdown, Esq., who had obtained the specimen from Miss Mary Ashley . The label states that it comes from the Kimmeridge Clay of Smallmouth Sands. It seems to have come from the formerly good exposure of Kimmeridge Clay between Sandsfoot and Ferry Bridge in Portland Harbour, referred to by Damon (1884) and from which a great dinosaur limb bone was found. This unusually large ichthyosaur is rare and not properly known. Thus Delair expressed the hope that the Kimmeridge Clay of the Weymouth area would be searched for remains of this "extreme" saurian. Amateur divers have a chance of finding more of this and other vertebrates in the Portland Harbour and Chesil Beach area.

The interesting story of this reptile continues. There is a later account by Delair (1986) . He rediscovered its left forelimb in a museum collection. This paddle was presented to the Natural History Museum by Miss Weld in 1902. The matrix is sandy and calcareous and the clay mineralogy has been studied by a former postgraduate of Southampton University. The bones seem to have come from the lowest part of the Kimmeridge Clay, the so-called "Junction Beds" or "Passage Beds".

Nannopterygius enthekiodon, Hulke

Ichthyosaur vertebra

This was a moderate-sized ichthyosaur with very small paddles (the smallest known amongst ichthyosaurs) and a very powerful tail (Delair, 1960) . It had small teeth with bulbous roots. In 1870 some teeth and two associated jaw fragments were found in the Kimmeridge Clay of Kimmeridge by Mansel-Pleydel, Esq. Later he found the major part of a skeleton in the Kimmeridge Clay of Kimmeridge Bay. This is now in the Natural History Museum, London. The bones seem to have been found in the ledges at low water and within the Aulacostephanus zones of the Lower Kimmeridge Clay Arkell (1933, p. 451) .

Description by Delair (1960):
"Of moderate size. Snout relative to the length of the cranium very long, though not so extreme as that of Leptopterygius latifrons. Orbit very large. Sclerotic plates present. Teeth small, with the crowns smooth and circular in cross-section, and the roots bulbous. Vertebrae with the cupping of the posterior faces of the centra confined to the central region, and the costal tubercles of the dorsals very small. Cervical vertebrae generally with a pentagonal contour of the terminal faces. Inner border of the coracoids greatly elongated. Femur long, with the trochanteric and opposite ridges moderately developed so that the lateral surface of the proximal portion is narrower than the dorsal."

For more information on Kimmeridge vertebrates including several excellent remains of ichthyosaurs see Etches and Clarke (1999). Steve Etches, fossil collector of Kimmeridge, has a large and impressive private collection of Kimmeridge Clay vertebrate remains. They are not discussed in detail here.

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ICHTHYOSAURS continued:

Kimmeridge Clay Ichthyosaur Paddle

Find of ichthyosaur bones, Kimmeridge Clay, Osmington Mills, Dorset

Nodule with bones - apparent top, Osmington Mills

Nodule with bones - apparent bottom, Osmington Mills

Difficulty in removing nodule with bones, Osmington Mills

On the 22 March 2003 Ian Troth, postgraduate research student and fossil collector, was walking back to Osmington Mills with Ian West after studying the section at Black Head. Ian Troth noticed some small bones on one side of a nodule. On turning it over it was seen to contain much bone material, probably including ribs and vertebrae of an ichthyosaur. These are shown on the images above.

The specimen clearly needed removing from the beach to a safe place and undergoing professional preparation so as to reveal the details of the bones. Removing it from the beach proved very difficult. Perhaps containing pyrite (of high density) it was extremely heavy to handle, being about the weight of a person. Ian Troth carried it up the beach and then with a car tow-rope tried to drag it towards Osmington Mills. This did not prove successful. Later, assistance was kindly provided by a member of the public who was on the beach.

Ichthyosaur paddle of Ian Troth, specimen prepared by Mark Hawkes

Bone structures of ichthyosaur paddles

Limb bones of an ichthyosaur, Kimmeridge Clay nodule, Lyme Regis

Later in the year (August) the specimen was seen after removal of limestone and careful preparation by Mark Hawkes of Stone Treasures. This well-preserved example of an ichthyosaur paddle remains in possession of the finder - Ian Troth. With a photograph of the prepared specimen there is also provided, for reference, a diagram showing the general skeletal structure of ichthyosaur paddles. Although this diagram shows the paddles of a Liassic ichthyosaur and the number and arrangement of phalanges varies between species, it should enable to reader to recognise, at least in part, the bone structure of the Osmington specimen. Compare the photograph with the diagram, and decide firstly which end is proximal and which is distal. Where should the humerus or femur be located? Which is the anterior side of the paddle? Can you tell whether this is fore-paddle or a hind-paddle?

In addition, to the right are shown two limb bones seen on the underside before preparation of the specimen. The humerus and the femur of the ichthyosaur are rather similar. However, the femur is likely to be smaller than the humerus. If, as you may consider, the prepared surface shows part of an upper limb bone, then these two have to be from the other pair of limbs. Do you think that they are femurs or humeri? These preliminary remarks are only based on the photographs. Ian Troth, no doubt, will provide more precise information later from a study of the prepared specimen and we await this with interest. He has already mentioned to me that there are also rib (costal) bones present and you can see parts of these in the right-hand photograph. It is an unusual specimen because so many bones are together in a relatively small septarian nodule.

Ichthyosaur fossilisation analogue - decomposing remains of a seal

Fossilisation processes like those which preserved the ichthyosaur remains are probably taking place at the present time. Here are shown the decomposing remains of a seal with the paddle or fin bones (phalanges) becoming visible together with part of the shoulder girdle. This is on a beach, at Pondfield Cove near Worbarrow Bay, and after the corpse has fully decomposed the bones will become scattered by the waves. If, however, this had sunk into suboxic or anoxic (black) mud, with some carbonate content, then the geochemical environment of the decomposing remains (producing ammonia etc) could initiate the development of a calcite septarian nodule.

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For more ichthyosaur photographs please go to:

More ichthyosaurs

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DINOSAURS:

Dinosaurs of the Kimmeridge Clay

Brachiosaurus

In 1868 the remarkable bone of a large saurian was found near Kimmeridge. In 1874 "a very large saurian limb-bone adapted for progression on land" was discovered on the shores of Portland Harbour. Damon in 1884 referred to the "gigantic saurian" as "Gigantosaurus megalonyx". These dinosaur bones found in the Kimmeridge Clay of Dorset are now known to be mostly from relatives of the Brachiosaurus, a huge, plant-eating, sauropod dinosaur with longer front legs than hind legs. To be more precise, the Kimmeridge bones are from the genus Ornithopsis which belongs to the Brachiosauridae. Palaeontological details have been discussed by Hulke (1869; 1874) , Mansel-Pleydell (1888) , and Delair (1959) .

No complete skeletons on this great creature are known from here and it is interesting as to why two humerus bones, shown below, have been found. The Kimmeridge Clay is a marine deposit and the carcasses were presumably brought down to the sea by rivers on the island of Cornubia (Devon and Cornwall) or the London-Brabant massif. Perhaps they drifted across the Kimmeridge sea losing bones as the bodies were destroyed by ichthyosaurs and other marine life. It is curious as to why members of the Brachiosauridae, in particular, are found. Did this type of dinosaur frequent the sea coast or were the large bodies more likely to be transported some distance to the open sea area of Dorset?

Dinosaur bone found in the Kimmeridge Clay of Portland Harbour

In the image, the relatively smaller bone on the right is an imperfect left humerus of Ornithopsis manseli (Lydekker, ex Hulke). It was found in the Kimmeridge Clay near Kimmeridge by J.C. Mansel-Pleydell Esq. The bone is 0.79m in length as it is preserved and is in the Natural History Museum, London. The bone has been described by Hulke (1869) but the locality information is a little difficult to understand. In a letter to Hulke, the discoverer, Mr Mansel-Pleydell, wrote that the bone was found in 1868

"amongst the layers of shale immediately above the band of cement-stone which rises from E. to W. on the west side of Clavell's Tower, between Kimmeridge Bay and Clavell's Head."

What does this mean exactly? No major cement-stone (dolomite bed) rises from E to W on the west side of Clavell's Tower and there is very little space between the tower and Kimmeridge Bay. A minor unit, Blake's Bed 42, is a cemented bituminous mudstone that does rise near Clavell's Tower. What was Clavell's Head? Was it, as I suspect, Clavell's Hard or Blackstone Point? If that is the case the location information may have erroneously referred to the west side of Clavell's Tower but really meant to refer to the east of the Tower. Here two cementstones, the Cattle Ledge and the Grey Ledge, appreciably worked for cement, rise from E. to W. in the stretch of cliffs between Kimmeridge Bay and Clavell's Hard. Perhaps the specimen was found above Cattle Ledge or Grey Ledge

Recently (2007) another dinosaur limb bone has been found by Steve Etches in the autissiodorensis Zone, Lower Kimmeridge Clay, at Brandy Bay, Kimmeridge.

Brachiosaurus skeleton

In the same image above on the left is shown the bone of a "giant saurian", and this is the one from Portland Harbour. It is a slightly imperfect left humerus of Ornithopsis humerocristatus (Hulke) found by Mr R.I. Smith. The position of the left humerus bone in a brachiosaur dinosaur is marked by "Hmr" in the image alongside on the left. The bones from the Dorset Kimmeridge Clay have appreciable resemblance to that in this skeleton, which was found in the Upper Jurassic strata of Tanzania..

The Portland Harbour bone seems to have come from a gritty clay bed in the Lower Kimmeridge Clay between Sandsfoot near Weymouth and Portland Ferry-bridge. The position of the bone in the strata was described by Damon (1884). The preserved specimen is 1.37m in length but probably was originally about 1.6m. It is in the Natural History Museum, London. The specimen was enveloped in large septarian masses, much fissured and cemented by sparry calcite and some parts have been distorted by compaction. The exposures have long been obscured by piling and embankments of the old railway line, but Damon gave a stratigraphical succession so that the horizon of what was then considered to be "Gigantosaurus megalonyx" can be established approximately in relation to other localities. It was quite near the base of the Kimmeridge Clay and near the top of the beds with the oyster Deltoideum delta. The sea was deepening from the oyster-rich shallows at this time. Other saurian, turtle and fish remains were also found at this fossiliferous locality. For more information on the palaeontological status of the dinosaur bone see Delair (1959), who mentioned, incidently, that this dinosaur is also known from Portugal.

An unidentified sauropod fibula has also been reported from the Kimmeridge Clay of Weymouth. There is a toe bone of another sauropod, Cetiosaurus, labelled, according to Delair, as from the "Kimmeridge Clay of Swanage". The Kimmeridge Clay does not occur at Swanage. Thus, this may be from the Kimmeridge Clay of Kimmeridge and be mislabelled in terms of locality or it may be from the Wealden which does occurs at Swanage and has been mislabelled in stratigraphical terms. The specimen is in the Natural History Museum. An imperfect bone, which is probably the dorsal half of a right pubis from the Kimmeridgian of Weymouth was considered by Delair to perhaps belong to Ornithopsis leedsi Hulke. Etches (1999) reported a possible dinosaur scapula from the Lower Kimmeridge Clay of the Blue Circle Cement Quarry, Westbury. At Kimmeridge Bay he found the small tail chevron of a dinosaur.

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DINOSAURS continued:

Kimmeridge Clay Dinosaur, Black Head

Dinosaur bone, Kimmeridge Clay

Dinosaur bone, cross-section 1

Dinosaur bone, cross-section 2

The photographs show a dinosaur bone from the lower part of the Kimmeridge Clay at Black Head, part-way up the cliff in the Blackhead Siltstone. Only a small part was initially visible and it was excavated. This bone was found in August 2001 by Mark Hawkes and Ian Troth. It is shown here in initial condition, before any treatment or restoration. It is in very shelly shale. There were no indications that other bones were present. The scale bar is in inches - one inch = 2.54cm. The specimen now resides at York Museum.

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PTEROSAURS

The long-tailed pterosaur Rhamphorhynchus sp. is known from one fragment from the Kimmeridge Clay of Kimmeridge (Delair, 1958) . The earliest Pterodactyls are of Kimmeridgian age and they persisted until the late Cretaceous. Pterodactylus manselli, Owen is known from the mutilated proximal end of a left humerus. It came from the Kimmeridge Clay of Weymouth (not Kimmeridge as is sometimes stated). Another bone is known (Delair, 1958) . Pterodactylus suprajurensis and other pterodactyle remains come from the Kimmeridge Clay of Weymouth. Damon (1884) referred to Pterodactyle bones having come from either east of Ringstead or from between Sandsfoot and Portland Harbour Ferry Bridge. Discoveries are still being made. More than 30 Pterosaur bones from the Kimmeridge Clay are recorded by Etches and Clarke (1999) , as a result of the remarkably diligent collecting of Steve Etches.

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CROCODILES

Crocodiles from the Kimmeridge Clay of Kimmeridge Bay include an incomplete snout of Teleosaurus megarhinus, Hulke. Remains of this genus have also been found in the Kimmeridge Clay of Weymouth (Delair, 1958) . Miss Ouless found Steneosaurus bones east of Ringstead cottages, Ringstead and at Ringstead itself in the the 1930s. Jaws of one of the largest known Jurassic crocodiles - Machimosaurus mosae, Sauvage and Lienard have been found at Kimmeridge Bay, although once described by Owen as Pliosaurus trochanterius (Delair, 1958) . Teeth of Dakosaurus have been discovered in the Kimmeridge Clay of Weymouth. Remains of the marine crocodile Metriorhynchus has been found in the Kimmeridge Clay of Weymouth.

For more crocodile remains see Etches and Clarke (1999) .

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CHELONIANS

These include remains of the freshwater tortoisePlesiochelys sp., and the more common marine turtles Pelobatochelys blakei, Seeley and Tropidodemys langi, Rutimeyer, all from the Kimmeridge Clay of Weymouth (Delair, 1958) . Etches and Clarke (1999) also report Pelobatochelys from near Kimmeridge.

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FISH

Thick phosphatic scales of the ganoid fish Lepidotes from the upper Kimmeridge Clay of Oday Common, Abingdon, found by Paul G. Oldfield

A set of ganoid fish scales, Lepidotes, from the Upper Kimmeridge Clay of Oday Common, Abingdon, found by Paul G. Oldfield

Some very well-preserved fish scales were found by Paul Oldfield in Upper Kimmeridge Clay with Pectinatites ammonites. The specimens were collected from Oday Common, Abingdon, grid reference 49109467, in June 1987. Unfortunately they had been disturbed by a mechanical digger, digging out a drainage ditch, so the remains were rather scattered. Hefound a flank with scales still in place on one side, the reverse shows a few scales with what might be part of the skull plus a couple of ribs with the crushed remants of Pectinatites and Protocardia. After several hours on his hands and knees he managed to find a further 58 isolated scales scattered over a two metre area, but unfortunately not much else. I thank Paul for this information.

For much more fossil fish from the Kimmeridge Clay, try to visit the Steve Etches Collection. Steve, the well-known Kimmeridge fossil collector has an excellent collection of Kimmeridge fossil fish on display in his private museum. Etches and Clarke (1999) have reported various fish from the Kimmeridge Clay, including complete skeletons. Remains of sharks and a ray fish have been found.

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PALAEONTOLOGY:

Coprolites

A coprolite containing phosphatic debris, Brandy Bay, Kimmeridge, Dorset, March 2012

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ECHINODERMS

Saccocoma, pelagic crinoid of the Kimmeridge Clay

Small, pyritised radial plates of the pelagic crinoid Saccocoma sp. occur in the vicinity of the oil shale, the Blackstone. The specimen shown here, after Arkell (1947), is 3.25mm in length (from top to bottom in the illustration). These small, metallic-looking objects are best seen on a freshly broken piece of oil shale. Arkell mentioned that their range is said to be only about 4m (13 feet) and are useful as indicating the main oil shale horizon in various parts of England (Bather, 1910) . Cox and Gallois (1981) have recorded these in the Kimmeridge area from the Blackstone, the Bubbicum and underlying oil shales.

Etches and Clarke (1999) have figured Pentacrinoids, various echinoids and Ophiuroids (brittle stars).

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AMMONITES

Various

A crushed ammonite, associated with oyster shells, Lower Kimmeridge Clay, Kimmeridge Bay, Dorset, 16th April 2014

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Crushed ammonite under water

An ammonite under shallow seawater at Clavell's Hard. This particular cephalopod has probably remained mostly below sea-level from the Jurassic Period to the present. Unlike most fossil illustrations, it is shown orientated as though the correct way-up, like a modern nautilus. The original aragonite of the shell is preserved. The specimen is probably from the Wheatleyensis Zone between the Grey Ledge and the Blackstone and can be seen on a shale ledge on the foreshore. The rippled water surface is reflecting the sky.

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Some Kimmeridge Clay ammonites, shown in a simple diagram, revised version, January 2016

Some brief notes on some of the ammonites shown above:

Pictonia bayei Salfeld. This is from Lower Kimmeridge Clay, Baylei Zone, Wootton Bassett, Wiltshire, England. The range is Lower Kimmeridgian, Baylei Zone. Diameter about 10 cm. This ammonite is not likely to be found at Kimmeridge because this zone is below sea-level here. It could be found at Ringstead.

Rasenia involuta Spath. This is from the Lower Kimmeridge Clay, Rasenia cymodoce Zone, Lincolnshire, England. The range is Lower Kimmeridgian, Cymodoce Zone. Diameter 5.5 cm.

Aulacostephanus pseudomutabilis (de Loriol). This is from the Lower Kimmeridge Clay, Pseudomutabilis Zone, Weymouth, Dorset, England. Range is Lower Kimmeridgian, Pseudomutabilis Zone. Diameter 5.2 cm. The genus Aulacostephanus can be found around the western side of Kimmeridge Bay out to Broad Bench and vicinity.

Pavlovia pallasioides (Neaverson). Hartwell Clay, Pallasioides Zone, Hartwell, Buckinghamshire, England. Range - Upper Kimmeridgian, Pallasioides Zone. Diameter - 7.6 cm. This can be found in Egmont Bight, some way below the Rotunda Nodules.

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Some more Kimmeridge Clay ammonites, after Arkell (1933), revised and relabelled version modified for the internet, January 2016

Image - More Ammonites of the Kimmeridge Clay. This is much modified after Arkell (1933) with names updated.

Details of specimens from Arkell (1933) are given here:

Pectinatities wheatleyensis (Neaverson), originally listed as Virgatosphinctoides wheatleyensis, Kimmeridge Clay, Wheatley, Oxfordshire, England. Holotype British Museum No. C 26897. From Neaverson, Ammonites of the Upper Kimmeridge Clay, plate 1, fig. 1. Maximum diameter - 122 mm. 33 28 48.

Gravesia gravesiana (d'Orbigny), Near Auxerre, Yonne, France. Syntype, Geno-syntype. From Palaeontologia Universalis, No. 178, figs. T 1 , T 1a. Maximum diameter - 85 mm. 34 76 42.

Aulacostephanus pseudomutabilis (de Loriol), Speeton Yorkshire, England. Geological Survey Collection, no. 18150. Specimen identified by Dr F.L. Kitchen. Maximum diameter 73 mm. 41 26 27.5.

Rasenia cymodoce (d'Orbigny), Lectotype, Genotype. Locality unknown. From Palaeontologia Universalis, No. 55. Maximum diameter 81 mm. 33 26.5 45.

Aulacostephanus mutabilis, originally listed as Pararasenia mutabilis (Sowerby), Horncastle, Lincolnshire. Holotype. British Museum (Natural History Museum, London), Sowerby Collection. Maximum diameter - 70 mm. 38.5 28.5 36.

Pictonia baylei Salfeld, Wootton Bassett, Wiltshire. J.W.T. Collection. Maximum diameter - 135 mm. 31 22 48.

(Arkell provided data on the height of the last whorl, the thickness of the last whorl and the width of the umbilicus, expressed as percentages of the diameter. These are the last 3 sets of numbers provided for each specimen.)

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A coarse-ribbed ammonite, still preserved as aragonite, in the Basalt Stone Band, a ferroan dolostone, Hudlestoni Zone, Upper Kimmeridge Clay, Rope Lake Head, east of  Kimmeridge Bay, Dorset, 31st March 2014

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AMMONITES -

Aulacostephanus

Aulacostephanus pseudomutabilits - an ammonite species from the Lower Kimmeridge Clay

The image above is of the ammonite Aulacostephanus pseudomutabilis , Lower Kimmeridge Clay, autissiodorensis Zone, Weymouth, Dorset. Ammonites of the genus Aulacostephanus can be recognised by the laterally compressed shell, the subinvolute coiling (i.e. partial overlapping) of the whorls, the fasciculate ribbing branching out from bullate tubercles on the umbilical (i.e. inner) shoulder. There is a prominant smooth ventral band, as shown in the image above. The genus is known from Europe and Russia and belongs to the superfamily Perisphinctaceae.

Examples of this genus (although most likely crushed and fragmentary) in the Lower Kimmeridge Clay which is well exposed from about the centre of Kimmeridge Bay to Broad Bench and beyond to the west. The tubercles and the branching ribs aid recognition; if an ammonite which fallen into the sediment on its venter, as occasionally happened, the smooth band on the venter will be easy to observe. This is not present in most other Kimmeridgian ammonite genera.

Aulacostephanus eudoxus, Kimmeridge Clay, Black Head area

An crushed ammonite preserved in calcitic condition in the southern part of Brandy Bay, Kimmeridge, Dorset, March 2012

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AMMONITES:

Pectinatites

Dr David Martill photographs a crushed specimen of Pectinatites, Upper Kimmeridge Bay, Brandy Bay, Dorset, March 2012

An ammonite, probably Pectinatites from the Upper Kimmeridge Bay, Dorset, in the Steve Etches Collection

The Steve Etches Collection contains many examples of Pectinatites. These are mostly crushed and pyritised. See the Steve Etches Catalogue ( Etches and Clarke, 1999) for details, dimensions and reference numbers (particularly Plate Ammonoidea 8).

The ammonite  - Pectinatites pectinatus of the Upper Kimmeridge Clay

Pectinatitid ammonites in a fallen block of mudstone at the foot of the cliffs between Cuddle and Clavell's Hard, Kimmeridge Bay, Dorset, 4th January 2007

A pectinatitid ammonite in bituminous shale of the Kimmeridge Clay of the Weymouth Relief Road, north of Littlemoor, Dorset, 30th June 2009

Here are some example of the ammonite genus Pectinatites established by Buckman in 1922. It is a genus of the Superfamily - Perisphinctaceae (i.e. a type of perisphinctid). It is common in the Upper Kimmeridge Clay, east of Kimmeridge Bay to the Freshwater Steps area. The specimens are usually crushed. They usually have many fine ribs.

In terms of morphology, these ammonites are subinvolute to subevolute. The inner whorls have biplicate ribbing. The microconch has ventral horns which are rarely seen, but present in specimens in the Steve Etches Collection. The macroconch has virgatotome ribbing (up to five secondary ribs can arise from a primary rib).

The Upper Kimmeridge Clay ammonite zones of Pectinatites elegans, Pectinatites scitulus, Pectinatites wheatleyensis and Pectinatites hudlestoni contain many crushed specimens. They can be seen on the ledges at low tide from Hen Cliff eastward.

Pectinatites - a common ammonite genus of the Upper Kimmeridge Clay

Shown above is the holotype of Pectinatites (Pectinatites) dorsetensis Cope, 1978. For details see Cope's (1978) paper. This holotype is from the top of Cope's bed 6, 18.2m above the Freshwater Steps Stone Band. The stratigraphical ranges of Pectinatites dorsetensis is: Upper Kimmeridgian, pectinatus Zone, paravirgatites Subzone, ranging from 11.0 to 18.2m above the Freshwater Steps Stone Band (Beds 7-6d of Cope, 1978).

An ammonite of the Kimmeridge Clay - Pectinatites cf. nasutus

Pectinatites cf. nasutus (Buckman), according to Arkell (1947). The specimen is from about 100m west of Freshwater Steps, 2 - 3m above the Freshwater Steps Stone Band. Image modified after Arkell (1947).

For more information on and for identification of Kimmeridge Clay ammonites see Cope (1967; 1978).

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AMMONITES continued:

Miscellaneous

An bed of brown marl with moulds of ammonites in the Lower Kimmeridge Clay, Weymouth Relief Road, Dorset, discovered by Dr. Ramues Gallois

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AMMONITES continued

Pectinatites sp.

A crushed Pectinatites ammonite, Upper Kimmeridge Clay, Brandy Bay, Kimmeridge, Dorset, March 2012

A coarse-ribbed ammonite, still preserved as aragonite, in the Basalt Stone Band, a ferroan dolostone, Hudlestoni Zone, Upper Kimmeridge Clay, Rope Lake Head, east of  Kimmeridge Bay, Dorset, 31st March 2014

. Crushed ammonites are common on the ledges of Brandy Bay (and elsewhere at Kimmeridge). The casual visitor is most unlikely to see any uncrushed specimens, but the well-known fossil collector Steve Etches has found uncrushed specimens. The usual ammonites, in the bay are species of Pectinatities from the Upper Kimmeridge Clay, but some other genera also occur. Note that there are microconches (female) and macroconches (male and with coarser ribbing) of Pectinatites, that can be found. The crushing is very thorough in most of the Kimmeridge Clay and reveals the great extent to which the Kimmeridge Clay sediment has been compacted, perhaps more than ten times in many cases.

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AMMONITES:

Aspidoceras sp.

An ammonite of the genus Aspidoceras in the Kimmeridge Clay of Brandy Bay, Kimmeridge, Dorset, March 2012

A specimen of Aspidoceras sp. was pointed out by Steve Etches in a block of argillaceous dolomite, associated with a ledge, in the middle part of Brandy Bay, March 2012.

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AMMONITES continued:

Pavlovia

The common ammonite Pavlovia rotunda from the rotunda Nodules of the Upper Kimmeridge Clay of Chapman's Pool, Dorset

Pavlovia rotunda - ammonite

Pavlovia rotunda gibbosa- ammonite

A fragment of the uncompacted body chamber of a Pavlovia ammonite in fallen debris at Egmont Bight, near Chapman's Pool, Dorset, 26th November 2011

A partially compacted Pavlovia ammonite, a Boreal perisphinctid, present in fallen debris of the Upper Kimmeridge Clay, Egmont Bight, near Chapman's Pool, Dorset, 26th November 2011

Pavlovia rotunda is an ammonite usually only found in incomplete form as parts of whorls in the Rotunda Nodules of the Upper Kimmeridge Clay at Chapman's Pool. The originally mud-filled body chamber has often been cemented into a nodule at an early stage before compaction. This part is thus preserved uncompacted. It is unusual for the empty inner whorls to be preserved by such early cementation. This image is based on a photograph of Arkell (1947), who figured this as a topotype (a specimen from the same locality as the original holotype). The white powdery material, like chalk, which occupies the site of the shell, is aragonite which has presumably lost its organic binding material and, thus, resembles the so-called "perished bivalves" of the Purbeck Formation.

The ammonite, Pavlovia rotunda gibbosa (Buckman, 1926), is a subspecies of Pavlovia rotunda (Sowerby, 1821). It was described in detail by Cope (1978) and this image is after a photograph of his. He commented that whilst the common P. rotunda was mature at about 100 to 120mm diameter, this subspecies was larger, reaching maturity at an estimated 300 - 400mm diameter. It was clearly quite a large ammonite. The specimen shown is entirely phragmocone, which explains its preservation. Sediment would have had access to all parts because the interior was not closed off by septa. There was again, presumably, early cementation to form a nodule. The stratigraphical range of Pavlovia rotunda gibbosa is: Upper Kimmeridgian, rotunda Zone, occurring in the rotunda Nodule Bed.

Part of an ammonite - Parvirgatites from the Paravirgatites Clays, Egmont Bight, near Chapman's Pool, Dorset

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AMMONITES continued:

Aptychi

Aptychus latus, an ammonite aptychus

Aptychi are paired flaps which were used for closing the aperture of an ammonite. Here is one of them. They are most common in the Lower Kimmeridge Clay, particularly the Aulacostephanus Zones, which are present in Kimmeridge Bay and the west of the bay round to the area of Broad Bench (Arkell, 1947) . The specimen is 3.6 cm from top to bottom, as shown.

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AMMONITES continued:

Ammonite Eggs (?)

A layer of ammonite eggs in the Lower Kimmeridge Clay, Weymouth Relief Road, Dorset, October 2009

Ammonite eggs have been described by Etches, Clarke and Callomon (2009) from Aulacostephanus Zones of the Lower Kimmeridge Clay and Pectinatites Zones of the Upper Kimmeridge Clay. The example of such eggs shown above come from the Lower Kimmeridge Clay of the Weymouth Relief Road. These were pointed out by James Codd after having been shown them by Dr. Ramues Gallois.

Etches, Clarke and Callomon (1929) summarised their paper in the journal Lethaia as follows:

"Eight clusters of small spherical and subspherical objects, some isolated and some associated with shells of perisphinctid ammonites, have been recovered from the Lower and Upper Kimmeridge Clay (Upper Jurassic) of the Dorset coast, England. They have been interpreted as ammonite egg sacs and represent the freshest and best-preserved examples known so far. Their structures and the ecological framework in which they occur are discussed. The parents are thought to be members of the two eudemic genera Aulacostephanus and Pectinatites that dominate the biostratigraphy of the ammonites in the range of the Kimmeridge Clay in which they occur. Isolated nuclei of ammonitellae have also been recovered."

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AMMONITES continued:

Ammonite Zonal Scheme

STAGE CHRONOZONE ZONAL AMMONITE
Bolonian

(Upper part of broader "Kimmeridgian" according to some previous authors. At Kimmeridge, the Upper Kimmeridge Clay, in the cliffs east of Kimmeridge Bay, and also west in part of Brandy Bay, corresponds to this. Includes Yellow Ledge, Kimmeridge oil shale, Rope Lake Head SB, White Band and associated shales etc.)

Fittoni Virgatopavlovia fittoni
Rotunda Pavlovia rotunda
Pallasioides Pavlovia pallasioides
Pectinatus Pectinatites pectinatus
Hudlestoni Pectinatites hudlestoni
Wheatleyensis Pectinatites wheatleyensis
Scitulus Pectinatites scitulus
Elegans Pectinatites elegans
Kimmeridgian

(Lower part of the broader "Kimmeridgian" as used by some previous authors. At Kimmeridge the Lower Kimmeridge Clay, within Kimmeridge Bay, corresponds to this. Includes the Flats , Washing Ledge, Maple Ledge Dolomite Beds and associated shales etc.)

Autissiodorensis Aulacostephanus autissiodorensis
Eudoxus Aulacostephanus eudoxus
Mutabilis Aulacostephanus mutabilis
Cymodoce Rasenia cymodoce
Bayliei Pictonia baylei

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CEPHALOPODS - TEUTHOIDS (SQUIDS) IN THE KIMMERIDGE CLAY

The remains of Teuthoids (Teuthoid Coleoids), a type of fossil squid (Order Teuthida) occur in the Kimmeridge Clay of Dorset. A specimen of Trachyteuthis sp. was found by Ian West in the Upper Kimmeridge Clay near Cuddle, east of Kimmeridge, on the 14th June 2013, while returning from filming with BBC staff. Photographs of the specimen are shown below. Incidently, specialists who have a particular interest in this subject matter in relation to the Kimmeridge Clay should, if possible, contact Steve Etches, the well-known Kimmeridge fossil collector. At the Steve Etches Museum, Kimmeridge he has several more specimens closely related to the particular specimen shown below.

I have just found a fossil Teuthoid, a fossil squid, in a block on the shore east of Kimmeridge Bay, Dorset, and a television crew stop to glance at it

A Teuthoid or fossil squid in a block on the beach east of Kimmeridge Bay, Dorset, 14th June 2013

A specimen of Trachyteuthis, a Teuthoid, or fossil squid, with ink sac, found by Ian West in the Upper Kimmeridge Clay of Kimmeridge, Dorset, 14th June 2013, and subsequently excavated by Steve Etches

Details of a fossil Teuthoid specimen of the Kimmeridge Clay, with ink sac, found east of  Kimmeridge Bay, Dorset, 14th June 2013

On the 14th June 2013, while involved in the filming of Kimmeridge oil shale for the BBC, I happened to find a good specimen of a fossil Kimmeridgian Teuthoid. It was in a block, ex situ on the beach east of Kimmeridge. I immediately notified the well-known fossil collector, Steve Etches, who is a specialist on sepiids and has a collection of them on display in his museum. He has since excavated and removed the specimen and it should be seen in his museum in due course.

For photographs of Trachyteuthis, including a preserved ink sac, see:

Etches, S. and Clarke, J. 1999. Steve Etches, Kimmeridge Collection, Illustrated Catalogue. Pages - Cephalopoda 1-7.

[For more information and so as to give a literature link and a connection to references, on a related Jurassic cephalopod subject see:

Fuch, D., Engeser, T. and Keupp, H. 2007. Gladius shape variation in coleoid cephalopod Trachyteuthis from the Upper Jurassic Nusplingen and Solnhofen Plattenkalks. By Dirk Fuchs, Theo Engeser and Helmut Keupp. Acta Palaeontologica Polonica. vol. 52 (3): pp. 575589. Available online as a pdf.

Although the fossil record of coleoid cephalopods is generally poor, the Upper Jurassic Nusplingen and Solnhofen Plattenkalks have provided numerous well-preserved coleoids. Trachyteuthis hastiformis, a comparatively large vam-pyropodcoleoid, was previously known to represent the sole species of its genus in Nusplingen and Solnhofen. However,morphological comparisons based on 50 specimens from different museum collections revealed two additional species: T. nusplingensis sp. nov. and T. teudopsiformis sp. nov. Both species lack the distinct spindle-shaped elevation on the gladius median field typical for T. hastiformis.
T. nusplingensis sp.nov. is clearly characterised by a smooth median field and a more or less regular granulation on the dorsal gladius surface, whereas T. teudopsiformis sp. nov. can be easily distinguished by the presence of a Teudopsis like median keeland an extremely narrow granulation.Morphometric analyses have shown that length-width indices are ambiguous characters to differentiate between the three species. Phylogeneti-cally, the keeled and anteriorly pointed T. teudopsiformis sp. nov. can be linked with the Early Jurassic genus Teudopsis and the Late Cretaceous genus Glyphiteuthis.]

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BRACHIOPODS

Lingula - brachiopod

Lingula ovalis Sowerby, a brachiopod which occurs in the Lingula Shales, uniform very calcareous mudstones near the top of the Kimmeridge Clay in Hounstout Cliff, west of Chapman's Pool. (Did the Lingula Shales have any similarity in conditions of deposition to the well-know and much older Lingula Flags of the Cambrian System of South Wales. Those sediments, contain Lingulella, are silty and sandy, though. Note that Lingula still exists at the present day.)

Discinisca - brachiopod

Discinisca latissima, a Kimmeridgian brachiopod of unusual circular shape. This is common in the Crushed Ammonoid Shales at Chapman's Pool and Egmont Point. It is sometimes accompanied with with crushed pavlovid ammonites, Lucina minuscula and other fossils (Strahan, 1898).

Torquirhychia inconstans

This is a brachiopod of "Rhynchonella" type which is common in the basal Kimmeridge strata, and can be quite easily found at Ringstead, for example. It isTorquirhychia inconstans (J. Sowerby), an asymmetric rhynchonellid (Brookfield, 1973c). It is widely distributed in the Baylei Zone of the Lower Kimmeridgian in southern England, from Dorset to Cambridge, but confined to one thin horizon. In the coastal exposures around Weymouth it is found only in the 30 - 45 cm thick Torquirhychia inconstans Bed. It is known not only at Ringstead, but also at Black Head to the west of Osmington Mills, and on the northwestern coast of Portland Harbour. In France it has a greater range, being found in both the Baylei and Cymodoce Zones (Brookfield, 1973c).

Brookfield (1973c) has argued that Torquirhychia inconstans was a brachiopod specially adapted to tidal environments. It is notable for the very asymmetric commissure (line of opening of the two valves) He suggested that this organism was probably best suited to an environment in which predominantly unidirectional currents were prone to reversal, as a result of tidal influence. The shell could swing round on a its pedicle attachment with the asymmetric commissure being in a favourable position whichever direction the shell was facing. Note, also, the gaping (partly open position) of the two valves that would have taken place after the death of the animal.

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BIVALVES:

Myophorella ("Trigonia")

The common, flat oyster of the Lower Kimmeridge Clay - Deltoideum delta

This oyster, Deltoideum delta (W. Smith), occurs in the Lower Kimmeridge Clay, particularly at Ringstead, near Weymouth. It is abundant in the base of the formation which was deposited in the very shallow water, marine conditions, needed for the flourishing of oysters. It also occurs in the topmost strata of the Corallian Group. It is a famous oyster, originally described by William Smith, the " Father of English Geology". and its triangular shape led to the original name - Ostrea delta. Notice the single adductor muscle. One central muscle is used for closing the valves in oysters, whereas two are present in most bivalves. Another interesting difference from most bivalves is that the shell is of calcite rather than the less stable aragonite. In addition the shell is thick. Thus fossil oyster shells are more resistant to dissolution than most shells and survive very well in Jurassic clay formations.

A specimen of Trigonia or Myophorella in the Kimmeridge Clay of Brandy Bay, Kimmeridge, Dorset, March 2012

The robust bivalves, commonly known as Trigonia, but more strictly Myophorella, are very common in the shallow water facies of the Corallian and the Portland Stone. They are not abundant in the deeper water Kimmeridge Clay. The occasional specimen does occur, as shown here. Normally they are present as isolated examples in the Kimmeridge Clay, whereas accumulations ("Trigonia Beds") occur in the Corallian.

Bivalve from the Kimmeridge Clay - Myophorella

This is a well-preserved Kimmeridge Clay specimen of "Trigonia", or Myophorella. I have record of the locality. I think that it is from the Houns-tout or Chapman's Pool area. At the bottom of the image some details are shown, including the interesting feature of some pairs of growth lines.

Trigonia - ancient and modern

"Trigonia" - ancient and modern. The Jurassic "Trigonia" or Myophorella is shown alongside its modern relative Neotrigonia margaritacea, the Australian Broach Clam, a "living fossil". This is a solid triangular shell with granulated ribs. The inside is pearly with large hinge teeth. The shell is pinkish white but with the brown periostracum shown here when fresh. The inside is gold tinged. It lives in southeastern Australia, including Tasmania (Dance, 1992). It is not suggested that the modern distant relative is living in the same conditions. It occurs in offshore mud. The general appearance of the shell is likely to have been similar though. The modern form has been used for making various kinds of ornaments, hence the name (Dance, 1992) (This guide by Dance to 500 species of seashells is very useful for finding modern analogues of ancient molluscs and is recommended).

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BIVALVES:

Lucina

Lucina minuscula

Lucina minuscula is a very abundant small bivalve of the Kimmeridge Clay. It is normally found in crushed condition in the shales. Look at split surfaces with white (aragonitic) shell remains. Recent relatives are suspension feeders and active deep burrowers with an anterior mucus-lined inhalent tube.

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BIVALVES:

Nanogyra

Shells of the bivalves - Nanogyra virgula and Protocardia,  Lower Kimmeridge Clay, Weymouth Relief Road, Littlemoor, Dorset, probably eudoxus Zone

Nanogyra virgula in the Lower Kimmeridge Clay, north of Littlemoor estate, Weymouth Relief Road, Dorset, October 2009

Nanogyra virgula or Exogyra virgula

This small oyster, Nanogyra virgula (J. Sowerby 1822), referred to in the older literature as Exogyra virgula, occurs only beneath the Yellow Ledge Dolomite Bed and is a common feature of the Lower Kimmeridge Clay at various localities Arkell (1947). This was the "Chama striata" of William Smith, who made the first geological map of England and called the Kimmeridge Clay - the Oaktree Clay. Exogyra virgula usually occurs crushed in the shales together with Protocardia, small Astarte and Lucina. Do not confuse it with another small oyster, Nanogyra nana, which is abundant at the top of the Kimmeridge Clay in the Portland Sand.

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BIVALVES:

Protocardia

Protocardia sp.

Protocardia is a genus of bivalves common in the Kimmeridge Clay. It can be found easily in the shale debris at the foot of Hen Cliff, east of Kimmeridge Bay (is it coming from the high autissiodorensis or from the low elegans Zone?). The species was referred to as Cardium striatulum Sowerby by Strahan (1898).

A close view of Protocardia specimens from the Lower Kimmeridge Clay of the Weymouth Relief Road, Dorset, October 2009

Well-preserved Protocardia specimens of small size are abundant in bituminous shale in a part of the Lower Kimmeridge Clay of the Weymouth Relief Road, north of Littlemoor, near Weymouth. These may be coming from the eudoxus Zone (KC 32 of Cox and Gallois, 1981). The shells of these small bivalves are remarkably thin-shelled. Why is this; was it a result of unfavourable sea conditions?

Species of Protocardia are common in Jurassic and Cretaceous strata and some species were clearly as tolerant of abnormal salinities as is the modern cockle - Cardium or Cerastoderma. There is no reason to believe that the salinity was abnormal in the case of the Kimmeridge Clay, but deficiency of oxygen may have been a problem at times. Protocardia can be described as a bivalve of rounded quadrate shape, that is equilateral. The beaks are directed inwards. The notable feature is the presence of radial ribs on the posterior slope. The remainder of the shell has fine comarginal ribs (ribs parallel with the margin). It is quite easily recognised by the ribs on one side only. It belongs to the Superfamily Cardiacea.

Some other Kimmeridge Clay bivalves not shown here but reported by Strahan (1898) include Ostrea duriuscula Phil., Ostrea laeviuscula Sowerby, Corbula sp., Astarte mysis(?). These, however, are old names and modern literature needs to be consulted to find current nomenclature.

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OTHER FOSSILS

This webpage is not at all comprehensive in listing fossils; it merely refers to a selection, as examples of the large fauna. Some parts this account, such as on the larger vertebrates, are more thorough but some are far too limited. Numerous bivalves and gastropods are present and not listed here. Numerous other fossil remains occur in the Kimmeridge Clay and images of a few more, with some text, will be added here from time to time.

Please see Etches and Clarke (1999) , for many impressive discoveries in recent years. Many bivalve and other fossils are mentioned in Blake (1875) . Damon (1884) . The various papers of Justin Delair are very useful regarding vertebrates.

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ACKNOWLEDGEMENTS

I would like to thank the photographer Barry Marsh for the photograph of the "Trigonia" and for helpful discussion. I am particularly obliged to Ian Troth and Mark Hawkes of Stone Treasures for the opportunity to show on the web page some of their remarkable vertebrate discoveries. I have had the good fortune to meet the well-known Kimmeridge Clay fossil specialist Steve Etches from time to time when out on the cliffs. His great collection houses the best specimens of vertebrate and invertebrate fossils from the Kimmeridge Clay. I thank Paul Oldfield for his kindness in allowing me to reproduce photographs which he has taken of Kimmeridge Clay fish remains from Abingdon. I much appreciate the advice and help of my daughter, Tonya Loades of Bartley West, Chartered Surveyors.

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BIBLIOGRAPHY AND REFERENCES - Kimmeridge

Please see separate Bibliography and References

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Dr Ian West, author of these webpages

Webpage - written and produced by:


Ian West, M.Sc. Ph.D. F.G.S.

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at his private address, Romsey, Hampshire, kindly supported by Southampton University,and web-hosted by courtesy of iSolutions of Southampton University. The website does not necessarily represent the views of Southampton University. The website is written privately from home in Romsey, unfunded and with no staff other than the author, but generously and freely published by Southampton University. Field trips shown in photographs do not necessarily have any connection with Southampton University and may have been private or have been run by various organisations.