If we were to go back in time about 320 million years, Somerset was covered by a warm shallow tropical sea, located close to the southern coast of a huge continent. This sea was inhabited by large numbers of shelled and calcified marine invertebrates which, when they died, added to the sediments on the sea-bed, that eventually were to form the limestone of the Mendip hills.
Land first emerged from this sea as a result of sediments washed out from vast river mouths to the north, eventually creating an environment that, as sea levels fluctuated over the millennia, would alternate between a marine estuary and a huge freshwater tropical swamp covered with the forests that created the Somerset coal fields. But land only really became consolidated here during the Permian and subsequent Triassic when shifting tectonic plates formed the continent of Pangaea. In Somerset the high ground of Exmoor and the Mendips were thrust up.
Little is known of the fauna that colonised Exmoor, due to the lack of fossils from the area. However, that of the Mendips, with their fossiliferous rocks, is better understood. The Mendips at this time were not the continuous range we know now, but were instead an archipelago of islands. The geological processes that resulted in their appearance coincided with a period of changing climate when the tropical forests gave way to a hot, dry desert environment. Consequently, the islands of the Mendip archipelago were to all intents and purposes desert islands, sparsely vegetated with horsetails, cycads and drought resistant conifers.
Given the depth of time that has elapsed, our understanding of the fauna occupying this environment can only ever be fragmentary. However, it is clear that by the Late Triassic there was a dynamic reptile community. Small lizard-like creatures were abundant, scuttling about on the ground and up in the trees and although this era pre-dates the dinosaurs’ great dominion of the earth, there were nevertheless several early, primitive dinosaur species roaming the land. Additionally, there were reptiles occupying both the shorelines and the seas around these islands.
Most of what we know about the prehistoric reptile fauna of Somerset during this period and beyond comes from evidence uncovered by quarrying operations, mostly during the nineteenth century when small quarries were liberally dotted around the county. Today most of them have been filled in but of those remaining, several have been conferred the status of ‘Sites of Special Scientific Interest’ on account of the fossils they contain. Among the most productive sites for Late Triassic reptile remains were quarries at Holwell, Emborough, Windsor Hill, and Ruishton, while some sites other than quarries, such as railway cuttings have also contributed. Today the small independent quarries are all but gone, overtaken by a predilection for cheap concrete blocks and a trend towards large quarrying conglomerates whose machinery would destroy a fossil long before it could be noticed. Consequently, today fossil hunters focus their attention on the late Triassic and early Jurassic cliffs along the coast between Blue Anchor and Hinkley Point which have always been productive, but are now the principal source of reptile fossils in the county.
What several of the old quarry sites have in common is that operations have exposed ancient fissures or caves into which streams or flood waters have washed the remains of long extinct fauna together with many tons of silt and rubble.
The celebrated nineteenth-century palaeontologist, Charles Moore from Ilminster, recognised that these fissures were remarkable repositories of fossil fragments, and spent much of his time during the 1860s examining them in the quarries around Somerset. He clearly had infinite patience as he washed and sieved many tons of rubble and silt using a hand lens to recover the tiniest teeth and bone fragments for identification. Most of this fragmentary material remains unidentified, packed away in the storerooms of various scientific institutions, but enough reptile species have been identified from these tiny remnants to give an insight into the Somerset herpetofauna of the past.
In Holwell quarry, Moore discovered teeth and scutes of a particularly interesting group of reptiles known as placodonts, which may well be the oldest reptile remains found in the county. Placodonts were reptiles that, having evolved from terrestrial ancestors returned to the sea, eventually developing a carapace, to closely resemble contemporary turtles. However, the earliest placodonts did not have any carapace and were not terribly well adapted to the marine environment. One such creature called Placodus, is the species to which the teeth from Holwell quarry belonged.
Placodus was around two metres long resembling a large stocky lizard. Its meagre adaptations for a marine existence consisted of webs of skin between the toes and a laterally compressed profile to the tail, making it rather oar-like. However its broad, flat, crushing teeth, together with the thick set, powerful head and short neck were perfect adaptations to its diet of shellfish for which it foraged along the Mendip shoreline or in the coastal shallows.
The later placodonts were much better adapted for an aquatic life, and it was to one of these that the scutes from Holwell belonged. This species known as Psephoderma anglicum, would have looked vaguely familiar to us, being covered by a carapace and resembling a marine turtle. The surface of the carapace had a knobbly texture to which the name Psephoderma or ‘pebbly skin’ relates. It was one of the largest placodonts reaching lengths of up to 180cm, and was also one of the latest, living close to the end of the Triassic shortly before the placodonts died out altogether. Like Placodus, it was specialised to feed on shellfish; but unlike Placodus its mouth was shaped rather like a beak, enabling it to pick the shellfish out from between rocks and other submerged debris. These placodont finds are curious and sit rather uncomfortably with the other fauna from the same geological bed. The deposits from Holwell date from the period when the Triassic was giving way to the Jurassic, a period thought to post-date the existence of placodonts, yet interestingly in the 1940s another person who greatly furthered our understanding of the prehistoric Mendip fauna, a German palaeontologist named Walter Keuhne, also found placodont remains in the same quarry, confirming Moore’s discoveries.
Also inhabiting the Late Triassic shoreline and in-shore waters were several carnivorous crocodile-like creatures. One, known as Pachystropheus rhaeticus has been found both in Holwell and also in a railway cutting in Chilcompton. Pachystropheus was a small animal rarely exceeding a metre in length, but there were some much larger crocodile-like animals around. In the quarry at Ruishton, Moore found teeth from a Phytosaur known as Belodon plieningeri. The Phytosaurs were fearsome predators, some species reaching up to 5 metres in length. They closely resembled crocodiles, both in their ecology and in their heavily-armoured body structure, but differed from them predominantly by the position of their nostrils. In crocodiles the nostrils are placed at the end of the snout, while those of the phytosaurs are situated on a bony hump far back on the snout, near the eyes.
Away from the shore in the interior of the islands, reptiles were also prolific. Among the commonest were Sphenodonts, or beak-heads. In the quarry at Emborough , remains of a sphenodont species known as Planocephalosaurus are plentiful. Planocephalosaurus was a small lizard-like ground-dwelling creature reaching a length of around 20cm. Evidence from other parts of the country would suggest that there may have been other species of Sphenodonts scuttling around alongside this one, although no further remains have yet been described from Somerset. However, in terms of numbers, they were probably the predominant group of reptiles inhabiting the area at the time. Most have long since become extinct, although somewhat bizarrely, two species cling on in New Zealand, literally as living fossils, where they are given the Maori name of Tuatara, referring to the crest of short spines running the length of their back.
Another ground dwelling species that was found in the interior of the islands was a curious creature known as a Trilophosaur. In 1957 Pamela Lamplugh Robinson identified some teeth from Emborough quarry as a species of Trilophosaur which she named Variodens inopinatus. These large herbivorous lizard-like creatures reached up to 2.5 metres in length and were unusual among the reptiles in having a heterodont dentition. Unlike mammals, the structure of the teeth of most reptiles is uniform and unspecialised, regardless of their position in the mouth. Variodens however, had simple conical teeth in the front of the jaw, while toward the back the teeth are wide and cusped for grinding vegetation.
Another essentially ground-dwelling species which has been found both in Holwell and also in Windsor Hill quarry is the mammal-like reptile Oligokyphus. This small creature superficially resembled a modern day weasel, but occupied an evolutionary position somewhere between the reptiles and the mammals. While technically a reptile, this would have been difficult to recognise as it possessed a range of characteristics found in the mammals, including being endothermic and covered in hair, albeit probably rather thin and wispy. It also held its legs vertically beneath its body in mammalian fashion rather than having them sprawled out at right angles to the body as the reptiles do. Its dentition was rather like that of a rodent with large front incisors and it probably scuttled about on the ground collecting pine cones and other plant material on which it fed.
There were also reptiles living in the trees on the islands. Perhaps the most striking among them being the small lizards found in Emborough quarry by Walter Kuehne and known as Kuehneosaurus latus. Kuehneosaurus was approximately 65 cm long, with greatly elongated ribs which, when at rest, were folded alongside the body, but which could be rotated horizontally to create a pair of skin covered gliding membranes or ‘wings’ with a span of about 30cm enabling the animal to glide from tree to tree. We can see these same adaptations today in the flying lizards of the Genus Draco inhabiting the forests of Southeast Asia with which Kuehneosaurus shared the body plan and gliding mechanism.
The late Triassic predates the period when Dinosaurs dominated the world. However, early species had appeared on the scene and Moore found teeth from two species in the quarry at Ruishton: Thecodontosaurus and Paleosaurus. Rather more complete remains of Thecodontosaurus were also famously discovered on Durdham Downs in Bristol in 1834, and the species appears to have been quite abundant in the region, with further discoveries from Tytherington quarry in South Gloucestershire and other nearby sites. Thecodontosaurus was a small plant-eating, theropod dinosaur rather reminiscent of a big turkey, reaching some two metres long and standing about a metre high.
Apart from the fragments found in Ruishton, remains of true dinosaurs have been elusive in Somerset, with one extraordinary exception. In 1893 William Sanford and Sydenham Hervey recovered the remains of a huge dinosaur from a small quarry in Wedmore. The following year, Sanford reported on this discovery in the Proceedings of the Somerset Archaeological and Natural History Society, from which it is worth quoting here:
‘Mr Hervey went into this quarry where the bones had been found and came out with a large fragment of bone on his shoulder, which I instantly recognised as the lower part of the large bone of the leg of a very large saurian. We collected a few other smaller fragments, and went to the cottage of one of the workmen, who had saved other bones from the quarry, and I obtained a nearly complete femur or thigh bone, a number of large portions of vertebrae or backbone joints, and some other fragments.’
In fact, Sanford ended up with an impressive left femur, nine vertebrae and some fragments of ribs, hips and toes, all of which can now be seen in the county museum in Taunton Castle. This is the most complete dinosaur ever found in the county and must have been an exciting discovery.
Based upon the structure of a couple of teeth found close to the bone site during a subsequent visit to the quarry, Sanford believed his dinosaur to be a large carnivore. However, this has subsequently been shown to be erroneous.
A succession of palaeontologists have studied the Wedmore dinosaur fossils since their discovery, each giving a slightly different interpretation of them and in some cases giving a different name to the creature to which they belonged. Sometimes the name given would reflect the animal’s Somerset heritage. Thus, in 1961 the creature was named Avalonianus referring to Avalon where King Arthur’s sword, Excalibur, was reputedly forged and where Wedmore lies. However, this description was based upon Sanford’s teeth and the name was specifically conferred on the animal to which the teeth belonged.
Subsequently it was determined that the teeth didn’t actually belong to the same animal as the rest of the skeleton and in 1985 Peter Galton renamed the creature Camelotia borealis, after Camelot, the seat of King Arthur’s court, thereby retaining the local connection and the species name borealis, meaning north, with reference to it being, at the time it was described, the only record of the family to which it belongs, from the northern hemisphere.
The teeth did, as Sanford recognised, belong to a carnivorous dinosaur, possibly a Megalosaurus which, if the identification is correct, would not have existed until much later than Camelotia itself. Camelotia though was an herbivore belonging to a group of dinosaurs known as the prosauropods. Both of these creatures would have been impressive beasts; Camelotia would probably have reached around ten metres long and would have weighed a couple of tons, while Megalosaurus was slightly smaller weighing in at around a ton.
The prosauropods are a truly ancient group of dinosaurs, the term literally meaning ‘before the sauropods’. Camelotia was extracted from rocks 205 million years old, older than the era when dinosaurs dominated the earth, and while Camelotia would have superficially resembled the sauropods, it was in fact much more primitive than them, and pre-dated its better known relatives.
While these are the only significant dinosaur bones to have been found in Somerset to date, evidence from the surrounding counties would suggest that there were other species of primitive dinosaurs in the region at the end of the Triassic, and that they were not altogether uncommon.
In geological terms, it was not long after the Wedmore dinosaur was browsing across the Mendip islands, that gradually rising sea levels resulted in the islands becoming once again completely submerged sometime during the early Jurassic. It was during this period, as the Triassic gave way to the Jurassic, that some of the finest fossilised reptiles found in Somerset lived; not dinosaurs but marine species, most commonly ichthyosaurs and plesiosaurs, for which Somerset is justly famous.
Much of the county sits atop a layer of rocks known as the Lias, which in some places may be many tens of metres thick. These rocks were laid down beneath the Somerset sea over a period of about 22 million years beginning close to the end of the Triassic some 200 million years ago and continuing through the early Jurassic until about 178 million years ago. The majority of the marine reptile fossils found in the county have come from these rocks. Geologists divide the Lias deposits into Lower, Middle and Upper Lias. The Lower Lias was deposited first, during the period between 200 million years ago and 185 million years ago, on top of this is the Middle Lias, deposited between 185 million years ago and 182 million years ago and finally on top of this are the Upper Lias rocks deposited between 182 million years ago and 178 million years ago. The ichthyosaurs and plesiosaurs of Somerset are found predominantly, though not exclusively, in the Lower Lias in a characteristic layer of blue mudstone.
Judging by the large numbers that have been found, ichthyosaurs must have been common in the shallow Somerset sea during the Late Triassic and Jurassic. Ichthyosaurs were large reptiles, strikingly similar in appearance to modern day river dolphins. Some species reached up to ten metres in length, although those found in Somerset rarely exceed three metres. They had large pectoral and pelvic paddle-like fins, a dorsal fin and a powerful propulsive tail fluke which, unlike dolphins, was vertical rather than horizontal and supported by a downward bend in the vertebral column. The eyes were huge, supported by a bony ring of plates that probably assisted with focus at depth. They had long thin snouts equipped with an array of sharp, pointed teeth perfect for catching the squid, and other cephalopods, on which they predominantly fed and which can often be found in the stomach contents of the finest fossils. They are known to have given birth to their young alive and fully developed as evidenced by the in-situ remains of embryos in a number of their fossils.
While a plethora of ichthyosaur species have been described or recorded from Somerset, this might have more to do with the nineteenth-century enthusiasm for taxonomy rather than being truly representative of the diversity present. Getting consensus on taxonomy can be fraught when the subjects still exist, but the difficulties are seriously compounded when the subjects have been dead for almost 200 million years and some of them exist only as fragments. As a result many of the species previously described are now considered to have been synonyms of one another, or at best to be dubious. The true picture is undoubtedly confusing and liable to change, but it seems at present that at least three separate species of ichthyosaurs have been reliably identified from the Lower Lias in Somerset: Ichthyosaurus communis, Leptonectes tenuirostris, and the wonderfully named Excalibosaurus costini, emphasising its Somerset distribution. Of these the most abundant is Ichthyosaurus communis. However, this is undoubtedly a composite species from which, in 2016, a further two species have been split, Ichthyosaurus larkini and Ichthyosaurus somersetensis which, if these changes become widely accepted, will increase the number of species of Lower Lias ichthyosaurs known to have existed in Somerset to five.
Plesiosaurs appear to have been slightly rarer than ichthyosaurs, and the discovery of a good plesiosaur fossil in Somerset is an exciting event. However, over the years a fair number have been found. Plesiosaurs were generally larger animals than ichthyosaurs, some species growing to around eight metres, although those from Somerset are smaller. They had broad, bulky bodies with relatively short tails, at least shorter than their body length, and long sinuous necks, ending in a rather small head. This shape has prompted some authors to describe them as a snake threaded through the shell of a turtle which, whilst not really accurate, describes the overall impression quite well. However, plesiosaurs did not possess a shell of any kind. Plesiosaurs swam using four powerful paddles with which they ‘flew’ through the water, rather as the marine turtles do now. They fed on fish and cephalopods which they caught by swift darting movements of the long neck. They have long been believed to have come ashore to lay eggs in much the same way as turtles, but recent evidence appears to challenge this view and suggests that they may have given birth to live, well-developed young.
Unsurprisingly the taxonomy of plesiosaurs is also rather confused and, as with ichthyosaurs, it might take a while before any consensus is reached. However, a 2012 review of plesiosaurs by Benson and his collaborators concludes that seven species have been recorded from the Lower Lias of Somerset. The Plesiosaurs found in Somerset are thought to represent early forms of the animals, particularly Eoplesiosaurus antiquior, a species discovered in Watchet, which may be the most basal species yet found.
The commonest species appears to be one named Thalassiodracon hawkinsii, prevalent in the area around Street,while other species recovered from the Street area include Eurycleidus arcuatus, Rhomaleosaurus megacephalus and Plesiosaurus cliduchus together with two further species whose names reflect their Somerset origins: Avalonnectes arturi and Stratesaurus taylori, ‘Strate’ being the name given to Street in the Domesday book. As the most abundant and arguably the most spectacular reptile fossils found in Somerset, the marine species have, in the past, attracted an eclectic array of local fossil collectors; prominent among them Thomas Hawkins, who lends his name to the Plesiosaur Thalassiodracon hawkinsii.
Thomas Hawkins, who lived from 1810 to 1889, was born in Glastonbury and lived much of his life at Sharpham Park near Street. Hawkins amassed a formidable collection of ichthyosaurs and plesiosaurs, many collected from the abundance of small quarries that sprang up around Somerset in the nineteenth-century supplying construction stone. Particularly productive areas of the county for Lower Lias ichthyosaurs and plesiosaurs have been the locality around Hatch-Beauchamp and Staple Fitzpaine and the area around Street. In fact, Street and its environs are so productive for fossilised ichthyosaurs that the ichthyosaur has been adopted as the emblem of Street and can be seen on the road signs as you enter the town.
As well as a collector, Hawkins was also a prolific dealer in fossils, buying from the quarrymen and various other fossil hunters, not only around Street but also farther afield, particularly Lyme Regis, and then selling them on to museums across the country. Many of the marine fossils in some of our most prestigious museums have passed through the hands of Hawkins, including the main collections of Street reptiles in the Natural History Museum in London, and those in the universities of Oxford and Cambridge. He was not though, by all accounts, a very likeable character. He is reputed to have been thoroughly eccentric and delusional, asserting that he was the rightful Earl of Kent and on one occasion claiming to have saved Robert Peel from an assassination attempt that Hawkins believed originated from Peel’s support for his sale of a collection of fossils to the Natural History Museum. Depending on peoples’ status in society he could either be an insufferable sycophant or a downright bully, and on one occasion was prosecuted for perjury. Quarrymen accused him of swindling them out of their finds, and he was certainly not averse to a little fraud. Many of his fossils were embellished with plaster; missing parts were often replaced, sometimes anatomically incorrectly, and additional vertebrae were sometimes added to increase the size of specimens.
The dynastic Quaker businessmen, the Clark family of Street, also took an interest in the fossils being excavated in the local mid-Somerset quarries in the nineteenth-century. In fact, in 1822 Thomas Clark supplied the first plesiosaur skull known to science; rather a relief for those pioneers of plesiosaur discovery, William Conybeare and Henry De La Beche, who had tenuously described these creatures for the first time just the previous year, from rather incomplete evidence.
However, the greatest collector among the extended Clark family was undoubtedly Alfred Gillett. Gillett was born in Langport in 1814, before moving to Street with his family, where he was brought up. He subsequently spent most of his working life in Yeovil. He had a long interest in geology, but it was not until his retirement when he returned to Street that he was able to focus on collecting fossils. He spent much of his time between 1868 and his death in 1904 extracting ichthyosaurs and plesiosaurs from the local Street quarries, although he was probably also buying them from local quarrymen. In 1887 he set up a museum in the Crispin Hall in Street to display his collection to the public.
Sadly the museum is long gone now, however much of Gillett’s collection still exists in the archives of the Clark family in Street. This impressive collection includes 12 large ichthyosaur skeletons across three species, together with a large plesiosaur skeleton, of the species Thalassiodracon hawkinsii, unfortunately missing its head and neck, but otherwise essentially complete. Among Gillett’s smaller fossils stored in the collection are numerous incomplete fragments of ichthyosaurs and the complete head of a plesiosaur.
All the ichthyosaurs and plesiosaurs discussed so far have come from the Lower Lias. However, this changed when, in the early 1840s, Charles Moore discovered what is probably the most extraordinary fossil bed ever found in Somerset: the Strawberry Bank.
Charles Moore has already been mentioned in relation to the Mendip quarries, but his enormous contribution to Somerset geology warrants further consideration of the man himself.
Moore was born in Ilminster in 1815. He expressed an interest in geology at an early age, but lacked opportunities to pursue his interest when, on reaching adulthood he moved to live in Bath. It was not until 1844 when Moore returned to Ilminster that his enthusiasm was re-awakened. Shortly after his return he discovered the Strawberry Bank fossil bed, a truly exciting find. In the Upper Lias stone of the Strawberry Bank quarry he found hundreds of fossils, predominantly of fish and insects, but also including crocodilians and ichthyosaurs. The geology of their preservation makes the Strawberry Bank fossils exquisite. Each fossil was discovered encapsulated in a nodule which when split revealed the fossil, not only in astonishing detail, but also in a three dimensional condition. The formation of nodules around the specimens has protected them from compression, so unlike most fossils they have not been flattened and instead appear largely as they would in life.
The Strawberry Bank ichthyosaurs, coming from the Upper Lias, are later examples, and consequently a different suite of species, than those that Gillett and Hawkins, and indeed Moore himself, were excavating from the Lower Lias quarries. These fossils have been quite accurately dated to a small time window some 181 million years ago. Moore collected at least eight ichthyosaurs from the site, across two species, Stenopterygius triscissus and Hauffiopteryx typicus and from the same site he also collected a number of specimens of a crocodilian known as Pelagosaurus typus. Most of the Moore collection today resides in the Bath Royal Literary and Scientific Institute where there are currently 22 specimens of Pelagosaurus typus. This species closely resembled the gavials found in India today, with the narrow snout typical of fish eating species. While Pelagosaurus could reach lengths of three metres, those from Ilminster are all considerably smaller and are considered juveniles, leading to speculation that the shallow seas in the area may have acted as some sort of nursery for the species.
Moore continued to collect large numbers of specimens from Strawberry Bank over a period of about 20 years, until eventually the quarry was filled in and the fossil bed was lost, probably forever as it now sits beneath a housing estate!
In 1853 Moore returned to live in Bath, where he persuaded the Bath Royal Literary and Scientific Institute to provide space for him to establish a museum to display his collection. His work in the Mendip quarries began after his return to Bath and his collection expanded constantly. He was highly active within the British geological fraternity, describing large numbers of new species and was a prolific writer on the subject.
By the time of his death, Moore’s museum boasted 43 near perfect examples of ichthyosaurs, plesiosaurs and crocodilians, not all by any means solely from Ilminster. Moore was also searching the mid-Somerset Lower Lias quarries, probably many of the same ones that Gillett and Hawkins were active in, and had amassed an impressive collection of ichthyosaurs and plesiosaurs from these too, which were mounted on the walls of his Bath museum.
Sadly the museum was dismantled after Moore’s death in 1881 and much of the collection was dispersed with few records kept to indicate which specimens were distributed or where they might have gone. Fortunately, however, the bulk of it still remains in storage in the Bath Royal Literary and Scientific Institute, with a smaller part at the Somerset County Museum, while some thirty Lower Lias ichthyosaurs have been stored at the Welsh National Museum in Cardiff pending their return to Bath. Copp et al, in an appendix to their 1996 paper on Charles Moore, have been able to trace a number of specimens in various other museums and institutions across the country, but the likelihood is that some important specimens may now be lost.
There is a great deal of material of herpetological interest among the Moore collection. The reptile remains from his work on the Mendips have already been discussed. Yet, assessment of the Mendip fossils is far from complete. For example, Moore writes of bones from Holwell of eight or nine genera of reptiles. To date these remain unidentified as, after the moth-balling of the collection, it all but disappeared for decades. But interest has now been rekindled in Moore and his collection so, in time, new species may be added to Somerset’s Late Triassic herpetofauna.
Most of the Lower Lias ichthyosaurs and plesiosaurs found across Somerset during the nineteenth-century have now either left the county or are in storage. Few are currently on public display locally. However, the museums in Wells and Watchet both have good specimens of ichthyosaurs on view whilst the county museum in Taunton has a small but fine juvenile on display. Rather bizarrely, there is also a raw, unprepared specimen cemented into the floor of the church at Stogursey. Additionally, there are aspirations to get the Gillett collection back on public display in Street and the Bath Royal Literary and Scientific Institute have in recent years staged occasional displays of the Strawberry Bank collection. Further afield, but still within easy reach, there are several ichthyosaur specimens from Somerset on display in the Museum and Art gallery in Bristol. These include an individual containing an embryo and a specimen of the curious species Excalibosaurus costini, in which the lower mandible is noticeably shorter than the upper, believed to have been an adaptation for probing the sea bed for food. Sadly, many important local specimens that were held in Bristol were destroyed on the night of 24th November 1940 when the museum suffered a direct hit from a bomb during the Bristol blitz.
There are even fewer plesiosaurs on public display locally although the county museum in Taunton has the Collard plesiosaur on display. This complete plesiosaur, fully articulated and in exceptional condition, was discovered by Nick Collard on the shore near Hinkley Point while out fishing in 2003. It has been described as the best preserved and most scientifically valuable plesiosaur fossil found in Britain for 150 years, and is well worth a visit.
Ichthyosaurs disappeared from the fossil record by the late Cretaceous, while plesiosaurs seem to have continued to exist up until the mass extinction event at the boundary between the Cretaceous and the Tertiary about 65 million years ago, which also saw the demise of the dinosaurs and many other species. At around the same time as these creatures were disappearing a new suite of reptile families were evolving, several of which still exist in Somerset today.
During the current Quaternary Period the climate has fluctuated cyclically as glaciation events have come and gone. During several of the warmer interglacial periods, the herpetofauna of Somerset has been richer than it is today, only for all to have been repeatedly lost during the intermittent glacial periods when the cold tundra landscapes became too challenging for ectotherms.
As the ice receded after each glaciation, species that had been extirpated could recolonise Britain from warmer southern climes, across the vast Doggerland Plain that until just 8,500 years ago connected Britain to the European mainland, but is now submerged beneath the North Sea and the English Channel. To investigate the ebb and flow of our contemporary herpetofauna we have to return once again to the quarries and caves of the Mendips.
The sediments in the Mendip caves are best known for containing the remains of the Pleistocene mammalian fauna. Impressive teeth and bones of cave bears, big cats, bison and other large mammals tend to steal the limelight from the herpetofauna. However, numerous remains of reptiles and amphibians have been recovered from the same sediments.
Westbury cave, near Westbury-sub-Mendip on the southern scarp of the Mendips, was formed over a million years ago and the sediment within it gathered during the Middle Pleistocene, from about 350,000 to 400,000 years ago. Within the lower sediments of this cave remains of the European pond turtle Emys orbicularis and Smooth snake Coronella austriaca have been found, representing the oldest Pleistocene reptile remains yet found in the county. Their presence in these lower sediments would suggest they existed here during the early part of this time-frame when conditions were considerably warmer than they are now.
Today the European pond turtle is more characteristic of central and southern Europe and it is unlikely that it could thrive in the current climate of Britain. The smooth snake likewise prefers warmer conditions, and while it does still exist in Britain today it is no longer found in Somerset, being restricted to warm low-lying heathland sites predominantly along the south coast. However, its discovery at Westbury suggests that the species must have had a considerably wider distribution across the country during at least one of the early interglacial periods of the Middle Pleistocene.
Three further species of reptiles, the adder Vipera berus, grass snake Natrix natrix and slow worm Anguis fragilis, have also been found in the Pleistocene deposits of Westbury cave, all of which can still be found in the area today. However, it is probable that since these bones were deposited these species have all been eradicated several times, by a series of intervening glacial periods and they exist here now simply because they were able to re-colonise after the most recent glaciation and before the inundation of the land bridge.
Together with these reptiles, the remains of two species of amphibians have been recovered from the higher, more recent sediments of Westbury cave.
Amphibians have a longer evolutionary history than reptiles, yet with the exception of some teeth found by Moore in the quarry at Ruishdon which he tentatively identified as being amphibian in origin, no earlier fossil evidence for the group has yet been found in Somerset.
It is possible that they may have been present intermittently during Somerset’s history, but for most of the time Somerset has been covered in salt or brackish water, an environment that amphibians have been unable to successfully exploit, so it is unlikely that they have been very successful here in the past.
The remains in Westbury cave belong to the common frog Rana temporaria, which is widespread today across the county, but also to another rather more exotic species, the parsley frog Pelobates punctatus. This species no longer exists in Britain although they can be found in northern France and would probably still be able to thrive in Britain, had they not presumably been extirpated by subsequent glacial conditions and failed to re-colonise before the land bridge was lost between Britain and the mainland.
While the fossils found in Westbury cave represent the oldest Quarternary herpetofauna found in the county, more recent remains have been discovered in several other caves on the Mendips.
Both Wookey Hole and Denny’s Hole, near Compton Bishop, have yielded bones of the natterjack toad Bufo calamita and the common frog. Those from Wookey Hole are believed to date from around 40,000 years ago while those from Denny’s Hole are thought to be much more recent, perhaps dating to around 12,000 years ago. The natterjack records are notable, particularly the most recent ones from Denny’s Hole as they probably represent the last time natterjack toads ever existed in Somerset.
While the natterjack does still exist in Britain, its distribution is very localised, confined to coastal dunes, heaths and salt-marshes. During the time that the Denny’s Hole natterjacks were living here, the Cheddar Valley, which Denny’s Hole overlooks, was under water, and the salt-marsh fringes of the Mendips must have provided some suitable habitat for them. The most recent glaciation, occurring between 11,000 and 10,500 years ago, presumably ended their occupation in Somerset, along with all the other herpetofauna present at that time and it is unlikely that natterjack toads have ever managed to recolonise the county since.
Milton Hill Cave north of Wells has also yielded remains of recent herpetofauna. Here the bones of common frogs, common toads, palmate newts, slow worms, grass snakes and possibly adders have been recovered, all believed to be about six to seven thousand years old. Thus, these remains post-date the most recent glaciation and represent the latest recolonisation, making them contemporaneous with the populations we see here today.