The Dinosaur Hunters: A True Story of Scientific Rivalry and the Discovery of the Prehistoric World

The main forum for geologists was in the scientific societies springing up in the metropolis such as the Geological Society and the longer-established Royal Society. But they were largely for gentlemen of rank and wealth, and gaining membership cost time and money. Of these, the Royal Society was the most famous; its Council had provided instructions for Captain Cook’s voyage of discovery and advised the government on scientific matters such as the best form of lightning conductors for buildings. The membership list read like the entries of the fashionable new guide to Society, Debrett. Lords, knights and men who ‘from their fortunes it might be desirable to retain as patrons of science’ dominated the list of Fellows. A shoemaker’s son, however brilliant, was largely invisible to this scientific community. But while in London, a chance meeting was to set Gideon Mantell on his future course.

In 1811, the year Mary Anning’s brother found the skull of the Ichthyosaurus, a distinguished doctor, James Parkinson, published the final volume of his studies on geology, Organic Remains of a Former World. Mantell may have been drawn to Parkinson because, like his father, he was a man of conscience, interested in reform. Parkinson had published such inflammatory pamphlets as While the Honest Poor are wanting Bread and Revolution without Bloodshed, advocating universal suffrage. He had even come dangerously close to transportation to Australia in 1794, when he was arrested for an alleged connection with the ‘Pop Gun Plot’ to assassinate King George III with a poisoned dart while he was at the opera. He was exonerated from treason, but after this incident he restricted his political interests to social reforms, to improving conditions for pauper children, and to treatments for the insane in asylums. James Parkinson is now better remembered as the doctor who first defined ‘Parkinson’s disease’, the degenerative illness marked by shaking and tremors.

At the beginning of the nineteenth century, though, Parkinson was equally well known as a geologist. Along with William Buckland and George Greenough, he was one of the founder members of the Geological Society and had embarked on a detailed survey of everything known about the ‘Ante-Diluvian World’. To Mantell in the Lewes library eagerly taking in the descriptions of the entire vegetable and animal fossil kingdom, Parkinson’s work was an inspiration. Putting aside any scruples about imposing on such an eminent gentleman, he made an appointment to visit Parkinson in Hoxton Square, Shoreditch, in East London.

His nervousness at seeking ‘the pleasure and the privilege’ of such an acquaintance was soon dispelled by James Parkinson’s ‘mild, courteous manner’, Mantell wrote, and the enthusiasm with which he ‘explained to me the principal objects in his cabinets and pointed out every source of information on fossil remains’. Parkinson had assiduously gathered details of Georges Cuvier’s studies in Paris and could tell Mantell of his famous discoveries: the giant extinct mammals, the mastodon, Megatherium and mammoth, and ancient species of crocodiles found around Honfleur and Le Havre. Cuvier believed that the fossil bones of crocodiles came from limestone beds of ‘very high antiquity … considerably older than those which contain the bones of quadrupeds’.

Parkinson had been greatly influenced by the pioneering work of the surveyor William Smith. Whereas Werner, in Saxony, identified rocks principally on the basis of their mineral composition, Smith had recognised that fossils could be used to help identify the beds. In his publication of 1811 Parkinson was careful to classify fossils according to the strata in which they were found; each layer of rock with its entombed fossils was for him a ‘former world’ which held the secrets of the history of the globe.

Parkinson, like Buckland, was intrigued by the conflict between geology and religion and was resolved ‘to shrink from no question … however repugnant to popular opinion’. He concluded that the account of Moses in the Bible ‘is confirmed in every respect, except as to the age of the world, and the distance of time between the completion of different parts of Creation’. Although there was no way of proving the earth’s antiquity, he acknowledged that the formation of the globe and the creation of life ‘must have been the work of a vast length of time’. Following an idea first raised by scholars in the eighteenth century, he reasoned that if the word ‘day’ in Genesis was used ‘to designate indefinite periods in which particular parts of the great work of Creation was accomplished, no difficulty will then remain’.

Parkinson fired the young Mantell with his romantic description of ‘former worlds’ buried in the rock. Each stratum enveloped evidence of a vanished existence, and the geologist could ‘begin to fathom the different revolutions which had swept over the earth in ages antecedent to all human record or tradition’. Parkinson wrote: ‘even the enormous chains of mountains which seem to load the surface of the earth are vast monuments in which these remains of former ages are entombed … they are hourly suffering those changes by which after thousands of years they become the chief constituent parts of gems; the limestone which forms the humble cottage of the peasant, or the marble which adorns the splendid palace of the Prince.’ The mountains, the hills and the land beneath their feet: all these were vast tombs more astounding than the pyramids.

It was through meetings with men like Parkinson that Mantell’s ambitions began to take shape. It was, he thought, the role of the scientist ‘to unveil God’s secrets … and unravel the mysteries of the beautiful world through which he was destined to pass’. James Parkinson had found time for geology while practising as a doctor. Mantell, too, would carry on his childhood dream. He would devote every spare minute to exploring these ancient memorials to a buried past that had existed, it seemed, before Adam. When he returned home to Sussex, he planned to make a systematic study of the strata and fossils of the county, a subject which he viewed as ‘replete with interest and instruction’. This married together his fascination with the subject and his desire to make a name for himself that might bring back honour to his family name.

At the age of twenty-one he gained his diploma of membership of the Royal College of Surgeons and returned to Lewes, where he was immediately offered a partnership with his former master, James Moore. It was soon apparent that he faced a gruelling workload as a country doctor. Epidemics of cholera, typhoid and smallpox still raged. ‘An immense number of Persons in this Town and neighbourhood are ill with Typhus Fever,’ he recorded in his diary on one occasion. ‘I have visited upwards of 40 or 50 patients every day for some time: yesterday I visited 64. The small pox is also very prevalent, 14 have died with it, Taylor in Malling Street who had it in 1794 is now covered with various pustules and has been very ill.’ Armed with little more than boxes of leeches, which were sent from London in boxes of two hundred, he struggled on against these deadly diseases.

His practice included attendance on the sick poor of three parishes, for which he was paid £20 a year, and treating the inmates of the Poor House at St John’s, near Lewes. Long before the development of emergency services, the local doctor provided the only care, even for the severely injured: ‘This morning I was summoned to Ringmer, a poor woman on the Green, Mrs Tasker, had set fire to her clothes and was most dreadfully burnt, it is scarcely possible she should survive.’ For five weeks he visited for an hour every day to change her dressings. When she died, he noted, ‘I am almost fatigued to death.’

There were numerous mills in the district for grinding corn, for producing rapeseed oil and flour, and for brewing or malting, and even for producing paper. With child labour, accidents were common and, without anaesthetic, invariably traumatic: ‘I was called to a most distressing accident at Chailey Mill. A poor boy got his clothes entangled by an upright post that was rapidly revolving; the lad in consequence was whirled round with great velocity and his legs were dashed against a beam. It was considered absolutely necessary to amputate the left leg above the knee, but the constitutional shock was so great that the poor boy died the next day.’

The hours of Gideon Mantell’s medical practice were long and unpredictable, especially since he excelled at midwifery, delivering between two and three hundred babies a year. At a time when the average mortality for women in some hospitals was as high as one in thirty, Mantell had only two deaths in over two thousand births during fifteen years. His great success came at a price: ‘frequently I have been up for six or seven nights in succession: an occasional hour’s sleep in my clothes being the only repose I could obtain’. Nonetheless, with his conscientiousness and tireless energy he gradually increased the profits on the practice from £250 a year to £750.

Despite the immense pressures of his medical workload, Mantell was prepared to sacrifice his few leisure hours to make headway in geology as well. With the carelessness of youth he spared himself nothing, often studying until the small hours and rising after just four hours’ sleep, to see his patients before embarking on some geological expedition.

There were numerous local pits and quarries such as Jenner’s quarry, Malling Hill Pit, Malling Street Pit, Southerham Pit, each laying bare the strata of Sussex. Following the approach of William Smith, he aimed to construct a geological chart of the correct sequence of the local rocks. He paid the pit labourers for any interesting fossils that he could add to his cabinet, and soon became familiar with the beautiful creatures of this former sea. To help identify the invertebrates, Mantell wrote to James Sowerby, a naturalist who was compiling a catalogue of fossil shells. There were many different species of ammonite, the extinct mollusc with a spiral shell that had so enchanted him as a child. In gratitude for the perfect specimens Mantell sent, Sowerby named one species after him: Ammonites mantelli. Embedded with the ammonites in the chalk were bivalves, sponges and another extinct mollusc, the belemnites, with their characteristic conical shell divided into chambers.

As Mantell gained in confidence, he established a network of correspondence with those of similar interest, such as the indefatigable Etheldred Benett – a woman of formidable intellect and serious endeavour, not one to swoon with delight at fashion’s latest dictates or, indeed, to follow them. Although from a prosperous family in Wiltshire, Miss Benett did not succumb to the usual conventions of a woman in county society. Rather than settling into marriage in some comfortable country rectory she stayed firmly unattached, and her pony carriage would often be seen on the hills of Wiltshire while she pursued her main interest, geology. She devoted her life to her collection, and became so well known that eventually her name alone in the literature would suffice to denote work of outstanding quality.

For Mantell such correspondence was both prestigious – she was, after all, a member of the gentry – and highly beneficial, since he could extend his knowledge beyond Sussex. He wrote to her in 1814, requesting ‘the honour of a correspondence’. Miss Benett graciously replied by sending a hamper of fossils to the wagon office in Lewes. Soon they were immersed in comparing the strata of Wiltshire and Sussex, trying to decide which rocks lay above and below others in the sequence. Although not yet known as such they were trying to unravel the sequence of ‘Cretaceous’ rocks across Southern England, which had been formed between 144 and 66 million years ago. Mantell was aided in this by another member of the gentry, George Greenough, who was busily engaged in developing his geological map of England with William Buckland. Greenough was only too keen to capitalise on Mantell’s enthusiasm, frequently requesting more detailed information on the Sussex rocks. By 1815, Mantell had already identified several different strata within the chalk formation around Lewes, the lowest being blue marl, then chalk marl, lower chalk and upper chalk. Greenough steered his research and provided advice on naming the rocks.

In the course of his medical duties, Gideon Mantell was summoned to the assistance of a Mr George Woodhouse, a prosperous gentleman who owned a linen-draper’s business in London. While giving ‘unremitting professional attention’ to Mr Woodhouse, Mantell could hardly fail to notice his patient’s eldest daughter Mary. Her portrait shows a young woman with a mass of dark curls piled high, and large, regarding eyes, her face set off by a fashionably off-the-shoulder dress. She shared his interest in fossils and gave him gifts – corals from Worcestershire and other curiosities she had found. They soon ‘formed an attachment’ and, it would appear, could not wait to get married.

The bride was only twenty, a minor in the eyes of the law, when she married in May 1816, by special licence and with the consent of her mother as guardian. Unfortunately, her father did not live to see the wedding. Thanking Mantell for his ‘professional exertions and kind attention’ shortly before he died, Mr Woodhouse presented him with a treasured gift of James Parkinson’s survey of the fossil kingdom.

Once settled in Lewes, Mary Mantell dutifully helped her husband with the painstaking task of searching for fossils, which was rapidly becoming his consuming interest. It was not uncommon for her to ride out with him on geological expeditions and sometimes even on his medical rounds, when she would check the ground for fossils while he visited patients. She soon found she could assist him with drawings of his finds, and patiently tried to master the art of scientific illustration. ‘I am much pleased with her [Mary’s] first attempt at etching,’ wrote Etheldred Benett to Mantell in 1817. ‘A little practice to enable her to work stronger and bolder appears to me all that is wanting to make them a great ornament to your work.’

With growing self-confidence in his geological observations, Gideon Mantell now decided to write a book setting out his findings on the rocks of Sussex, which he hoped would establish his scientific credentials and perhaps secure his membership of one of the prestigious scientific societies. Mary undertook the illustrations: a fragment of the claw of a crustacean, part of the dorsal fin of a fish, the extraordinary sharp spines of the Plagiostoma spinosa – all the dismembered bits of Nature in their incredible variety. With his wife’s total support and interest, Mantell described his happiness after his marriage as ‘greater than ever’.

As Gideon Mantell began to explore further afield, he realised that there was very different rock to be found in an area known as the Weald, a forest-covered ridge lying between the chalk hills of the North and South Downs. ‘Advancing from the Downs, an outcrop of sandstone is first seen near Taylor’s bridge,’ he observed, ‘and it subsequently appears by the stream that winds along Cuckfield park. At this spot in Whiteman’s Green an excavation has been made.’ As he approached the quarry, he could see tucked below the gorse, wild thyme and trees clinging to the rocks at the surface, the Weald strata exposed to a depth of some forty feet. There were horizontal layers of sandstone, limestone and slate, lying on a bed of blue clays.

With growing excitement, as he examined fragments of rock he began to realise that the fossils entombed in the layers of sandstone and limestone at Whiteman’s Green were quite unlike the invertebrates of the chalk hills around Lewes. Embedded among the debris appeared to be petrified fragments of larger bones. He mentioned this in his letters to George Greenough and Etheldred Benett in the autumn of 1817, explaining that he had uncovered the teeth and bones of vertebrates: amphibia, perhaps crocodiles or alligators. However, the fossils were so mutilated and worn that they were almost impossible to interpret or classify. The logical, tidy plans of the past months, the neat orderly drawings of invertebrates, everything that had fired his imagination about the former sea of chalk, began to be overshadowed by these curious fossil beds.

Whiteman’s Green was too far from Lewes for Mantell to ride out each day, and with the arrival of his first child, Ellen Maria, in 1818 he had even less time than before. So he began negotiations with a Mr Leney who ran the quarry, and during the next year parcels from Cuckfield began to arrive at the Lewes wagon office. The first delivery was not particularly exciting: ‘the bones, teeth and the tongue of a fish’. After another abortive trip when ‘it rained in torrents nearly the whole of our journey’, Mantell ‘made further arrangements with Leney respecting the Cuckfield fossils’. He is likely to have taught the quarryman to search for the remains of larger bones. It wasn’t long before several packages arrived from him, including some fossils that Mantell described as ‘superb specimens’.

Among the fragments of larger bones there were also invertebrates, such as tiny fossil shells and snails. Mantell tried to describe these to Etheldred Benett, although he admitted they were so damaged ‘it is scarcely possible to ascertain the genera or species’. Nonetheless, Miss Benett thought the shells from the Weald were similar to those uncovered in a rock she knew called ‘Purbeck limestone’. This is a formation that stretches across Wiltshire and Dorset that was well established in the geological sequence as Secondary rock. The Weald and the Purbeck, Mantell wrote, following Miss Benett’s advice, ‘correspond in so many particulars … that there is every reason to suppose that they belong to the same formation’. If this was true, the rocks at Whiteman’s Green in the Weald lay well below the chalk at the top of the Secondary series. He was revealing tantalising glimpses of a former world that had thrived an unknown number of years before the fishes and ammonites embedded in the chalk.

All this time Mantell’s medical practice prospered, and he was able to buy a house in Castle Place from his former partner, James Moore, for £700. By 1819 he could afford the house next door and the two houses were knocked together, becoming known, grandly, as ‘Castle Place’. Positioned prominently in the High Street and backing on to Lewes Castle, the imposing home was a world apart from the modest cottage in St Mary’s Lane where Mantell had been brought up. A team of craftsmen was hired to create a gracious interior with Georgian windows to the floor, ornamental arches over the stairwell and even carvings of ammonites to decorate the Ionic columns at the front of the house. As if to complete the metamorphosis from bootmaker’s son to doctor of standing, Mantell adopted the coat-of-arms of his forebears and painted them, entwined with those of Woodhouse, on the porch outside and on the marble table in the dining-room. But if Mary Mantell was under any illusion that she might acquire an elegant new drawing-room to entertain guests, she was to be disappointed. Her husband’s burgeoning ‘little cabinet’ became a grand ‘Collection’ and quickly came to fill the new first-floor drawing-room.

As news of Gideon Mantell’s collection spread, visitors came to view the fossils. One caller was that same Lieutenant-Colonel Thomas Birch who had sought out Mary Anning; Mantell described him as a ‘very agreeable and intelligent man’. Birch had been touring the West Country and had spent much time in Dorset buying fossils of the Ichthyosaurus – or ‘Proteosaurus’ as it was still called – from Mary. Naturally, Mantell was intrigued to know how Birch’s giant Ichthyosaurus bones compared to the fragments he had found. In March 1820, shortly after the birth of his second son, Walter Baldock, Mantell received an intriguing letter from Lieutenant-Colonel Birch.

‘I am going to sell my collection for the benefit of the poor woman and her son and daughter at Lyme who have in truth found almost all the fine things,’ Birch wrote. ‘I found these people, the Annings, in considerable difficulty – on the act of selling their furniture to pay their rent – in consequence of their not having found one good fossil for near a twelvemonth. I may never again possess what I am about to part with; yet in doing it I shall have the satisfaction of knowing that the money will be well applied.’

Birch was genuinely concerned that the Annings had not been able to maintain their early success. Apart from an Ichthyosaurus uncovered in 1818, they had had no more significant finds. Birch’s sale was planned for 15 May, in the Egyptian Hall in Piccadilly. Gideon Mantell attended the auction and had a chance to see Mary Anning’s ‘marine lizards’: an Ichthyosaur femur and head that was bought for Georges Cuvier in Paris, a partial skeleton, vertebrae and other fossils. Lieutenant-Colonel Birch’s sale raised £400 for the Annings.

Less than a month later, in June 1820, Gideon Mantell entered in his diary: ‘received a packet of fossils from Cuckfield. Among them was a fine fragment of an enormous bone; several vertebrae and some teeth.’ Having met Birch and seen Mary Anning’s giant sea lizards, he immediately wrote that these giant bones must belong to a ‘Proteosaurus or Ichthyosaurus.’ After all, this was the only large creature that had been described in England. Inspired by this discovery of the largest bone he had received so far, he began a series of excursions to Whiteman’s Green in the Weald, the mundane little quarry where workmen laboured for basic stone material, unaware that they were laying bare the secrets of the past. To Mantell the quarry was a magical place; it was like entering the ancient tombs, where extraordinary records of a former world were waiting to be explored. With great enthusiasm, on 16 August 1820 he took the entire family on an outing to the quarry: ‘We made an excursion to Cuckfield; my brother drove the ladies in his chaise and I rode on horseback.’

But the more specimens he found, the more baffling the site became. Strangely, although he believed the animal bones belonged to an Ichthyosaurus, or sea lizard, he began to find the petrified remains of land plants. These fossils were difficult to interpret, some blackened like charcoal, with cracks and fissures filled with white crystalline minerals or the brilliant bronze of fool’s gold. As he scrutinised the stone, he thought he could discern fragmentary remains of leaves, stems and other ‘ligneous structures’, which appeared to be of vegetable origin.

Before 1820, very little was known of fossil botany. In the eighteenth century, Carl Linnaeus had developed a detailed classification system for plants, establishing in his catalogues of several thousand plant species from all over the world the ground rules that a botanist should follow to describe and name plants correctly. Since then, other scholars had occasionally attempted to identify fossil plants, but there were few systematic studies of fossil species before 1820, and names had no legal status. Faced with tantalising impressions of the relics of plants that he could not recognise, Mantell had no knowledgeable source to which he could turn. ‘I am unacquainted with any vegetables either recent or fossil with which these remains can be identified,’ he wrote.

During one trip to the quarry at Cuckfield in 1820 he had a breakthrough. He unearthed, buried with more giant bones, part of a tree trunk more than three feet long, very weathered, with the rudiments of branches. He could see at once that the trunk was covered in distinctive diamond-shaped scars, resembling woody bases where leaf stalks were once attached. This was nothing like the English trees around him, the familiar indentations on the bark of oaks, chestnuts and birches. The roughened surface of the trunk, the pattern of scars from woody leaf stalks, were striking – like those of a tropical palm.

Mantell soon found other fossils, too, which bore more resemblance to a tropical flora. Some of the leaves and stems he thought were like Euphorbia from the East Indies, a lush, flowering shrub. With some confidence he entered in his journal on 17 August 1820: ‘Had a very fine specimen of Euphorbia from Cuckfield.’ Two weeks later, he sent ‘a large and beautiful specimen of fossil Euphorbia from Cuckfield to Mr Greenough … it was embedded in mastic, the same composition as used for the Minerets and Domes of the oriental palace at Brighton’. In fact, flowering plants, like Euphorbia and palms, had not yet appeared on the map of the primitive landscape. The history of fossil plants and the habitat for Mantell’s unknown giant creature were stranger than anything he could anticipate with the limited evidence then available to him.

In 1821, as Mantell was trying to find out more about tropical plants and animals, the Reverend William Conybeare completed his detailed study of Ichthyosaurus for the Geological Society. This was to provide another clue to the giant bones. Conybeare had included beautiful anatomical drawings of the bones of Ichthyosaurus. When Mantell compared the fossil bones that he had uncovered at Whiteman’s Green in the Weald, he found that they were very different from those of the sea lizard of Lyme. The vertebrae of an ichthyosaur were slender and deeply hollowed, allowing for the flexible movements of an animal living in water – nothing like the chunky, solid vertebrae that he had uncovered in Sussex. The leg bone of the Ichthyosaurus was more like the fin of a fish; the slender central bone, the humerus, ‘immediately supporting a very numerous series of small bones, form[ed] a very flexible paddle’. But the portion of giant femur, or thigh bone, that he had found in the Weald bore no resemblance to any bone in the sea lizard. It was truly enormous: the fragment, of the top part of the bone, was over two feet long and twenty inches in circumference. If this fragment of a giant leg was not derived from an Ichthyosaurus, then to what kind of monstrous creature could it belong?

Apart from the shape of the bones, there was another clue that the unknown creature from the Weald was not a sea lizard. When a creature dies at sea, its body sinks down to the ocean floor and is gradually covered by a fine rain of particles that form the new sediments. As it is gradually densely packed with layers of sediment accumulating above, the bony skeleton can be well preserved, just like the ichthyosaurs of Lyme. But when a creature dies on land it is much more likely to be destroyed, falling prey to some other animal or scattered by wind and rain, leaving only a confused jumble of bones. Mantell could recover only fragments of bone from the Weald, never a full skeleton. As yet, he had not even found two bones joined together. It occurred to him that these worn relics of giant bones might have belonged to a creature that spent at least part of its life on land, beneath the shade of palms.

In the quiet of night, when all the town was long since asleep and his medical duties were completed, Gideon Mantell studied the fossils he had found, so utterly absorbed in his work that he was often unaware that the small hours were approaching. With careful use of chisel and hammer, the shape of the bones slowly emerged from the surrounding stone like some strange primordial sculpture, perhaps more impressive than something that is finished, containing all the promise of a great work of art gradually taking shape before his eyes. He would glimpse eerie fragments of the ancient animal: the exquisitely smooth curve of the giant femur, the sharp points of the damaged vertebrae, the strange ridges on the enamel of the teeth; the foramina, or holes, for blood vessels, far larger than any human capillary. It was unearthly.

To try to make more sense of this confusing picture, he would use as a reference Georges Cuvier’s acclaimed four-volume summary, Recherches sur les Ossemens Fossiles des Quadrupèdes, which had been translated into English in 1813. Here Cuvier outlined the details of several species of ancient extinct crocodiles found at Honfleur and Le Havre. Mantell compared his fossils against Cuvier’s drawings, and some of the bones, especially the vertebrae, seemed to correspond. To obtain a second opinion, he now made arrangements to view the Hunterian Museum at the Royal College of Surgeons in London. John Hunter’s collection of ten thousand anatomical specimens had been bought by the government after his death in 1793 and placed in the Royal College at Lincoln’s Inn Fields. Here, they were being catalogued by Hunter’s former apprentice, William Clift.

The child of a poor family in Devon, Clift possessed an exceptional talent for drawing which had been noticed by the local gentry, and he had been sent to assist Hunter. Greatly honoured by this appointment, the young Clift had laboured long hours for little pay, helping with dissections before breakfast at six in the morning and often not finishing until after midnight, the evenings being spent in dictation. Within a year of his apprenticeship, Hunter died, but he revered his former master and was determined to continue his work.

Although hampered by the fact that Sir Everard Home had removed many manuscripts that would have helped to identify the specimens, Clift struggled on, trying to prepare Hunter’s collection for public view. By the 1820s, his experience was considerable. When Gideon Mantell presented him with one of the pointed, curved teeth he had found, Clift did not hesitate: ‘there can be no doubt of its having belonged either to the crocodile or the monitor [lizard]. I know of no animal whose teeth have the lateral ridges so strongly defined.’

From such discussions with Clift and comparisons with Cuvier, Mantell began to think that at least some of the giant bones could be assigned, not to a sea lizard, but to an ancient species of crocodile. He wrote in summer 1821 to a friend, the MP and Fellow of the Royal Society Davies Gilbert, telling him of the giant bones of crocodiles that he had found that spring in the Weald. ‘There can be no hesitation,’ said Mantell confidently, in assigning them to ‘the same unknown species of Crocodile, as discovered at Honfleur and Havre’.

But soon after this, Mary Mantell made a remarkable discovery that did not fit this conclusion. There are several versions of the event; the most plausible recounts that the incident occurred one morning in 1820 or 1821, when Mary was accompanying her husband on his medical rounds. While waiting for him to see his patient, she searched for fossils. As she walked, her eyes were irresistibly drawn to a strange shape in a pile of stones that had been heaped by the side of the road. Picking up the stone, she brushed away the white dust, gently removing any loose rock with her fingers. Gradually a shape emerged never previously seen by human eye. It was very smooth, worn and dark brown, rather like a flattened fragment of a giant tooth.

When she showed her husband, he saw at once that this was something important. ‘Soon after my first discovery of colossal bones,’ he wrote, ‘some teeth of a very remarkable character particularly excited my curiosity for they were wholly unlike any that had previously come under my observation.’ The fragment of tooth was more than an inch long, and shaped into a blunt, grinding surface at the crown. The couple were able to trace the source of the pile of stones to the same quarry in Whiteman’s Green in which Mantell had found the other giant bones. ‘Even the quarrymen, accustomed to collect the remains of fishes, shells and other objects embedded in the rocks,’ he wrote, ‘had not observed fossils of this kind and were not aware of the presence of such teeth in the stone they were constantly breaking for the roads.’

The ‘tooth’ cast all his observations into doubt. He could see that this was not the tooth of a crocodile, for it did not have the sharp, pointed crown essential for a carnivore. It had a broad, flattened grinding surface, supported by thick enamel on one side and with a marked ridge up the middle. This was much more like the tooth of a herbivorous mammal, that had been worn down by constant chewing. ‘The first specimen so entirely resembled the part of the incisor of a large mammal,’ he wrote, ‘that I was much embarrassed to account for its presence in such ancient strata, in which according to all geological experience, no fossil remains of mammal would ever be discovered.’

Although the tooth resembled a herbivorous mammal like a hippopotamus or rhinoceros, such creatures were not supposed to exist in ancient rock. Cuvier’s extinct large mammals such as the mammoth and mastodon had been retrieved from Tertiary deposits. Mantell thought from his correspondence with Etheldred Benett that Weald rocks were much older, from the Secondary period. To suggest that mammals had lived in ancient times was one step beyond anything that naturalists could envisage. As James Parkinson had written, although the time-scale of Creation as outlined in Moses had been questioned, the order of Creation was not in doubt. Parkinson thought it striking that the order of creation as stated in the Scriptures was ‘in close agreement’ with geological evidence: ‘The Creative Power has been exercised with increasing excellence in its objects … the last and highest work appearing to be Man.’ No one had yet challenged the assumption that mammals were created last, when God had prepared the Earth for the higher animals.

This belief informed Mantell’s quest; he did not yet have enough evidence to disregard the huge burden of accepted wisdom. He asked himself, if the owner of the tooth was not a large mammal, then what was it? The tooth did not resemble that of any fish at the Hunterian Museum. It could not come from a turtle; they have no teeth, only horny beaks. No amphibian was known to reach giant proportions. And it certainly was not from a bird – no toothed birds had been reported at this time. By a process of elimination the evidence pointed to a bizarre conclusion: the teeth belonged to a giant herbivorous lizard.

Yet this conclusion made no sense. ‘As no known, existing reptiles are capable of masticating their food I could not venture to assign the tooth in question to a lizard,’ wrote Mantell. A herbivorous reptile that could chew its food like a cow was unheard of. It was a preposterous idea. The experts in London, such as William Clift, were following Georges Cuvier, interpreting the fossil record by analogy to living forms. But there was no modern analogue to such a strange reptile.

Gideon Mantell lacked the one piece of evidence that would have proved the tooth belonged to a reptile: a fossilised jaw. A mammal’s jaw is very distinctive. Even if the teeth are missing, there are differently shaped spaces for the various types of teeth: molars, premolars, incisors and canines. A reptile does not have several types of teeth; although its teeth may vary in size, the sockets are all the same shape. But Mantell could not find a jaw, just a single disembodied tooth.

When he studied the tooth at home, in his drawing-room, surrounded by his collection, in moments of doubt – the large fragment of tooth was so worn – he sometimes wondered if he had found anything at all. Viewed from some directions it was almost unrecognisable as a tooth. Fine, feathery black lines were woven across the surface like a spider’s web. There it lay in his hand, a scrap of a fossil scarcely larger than a pebble, withholding the secret to an unknown past.

During the summer of 1821 Mantell redoubled his efforts to gather any evidence that could shed more light on the mystery. Scarcely interrupted by the major events of the day – the death of Emperor Napoleon on St Helena, the spectacular coronation of the ageing King George IV, the summer races and Brighton fair – he struggled with his geological research whenever time could be spared from his practice. Sometimes he took the single-horse chaise to Cuckfield with his young apprentice, George Rollo; occasionally he rode out alone to hunt for further evidence of his monster.

By the autumn, Mantell’s first-floor rooms were filled with a strange assortment of fragments of giant bones uncovered in the Weald. From his knowledge of anatomy while training as a doctor he was able to identify several of them. He wrote to the Reverend Conybeare at the Geological Society, telling him that he had ‘ribs; clavicle [part of the shoulder]; radius [forearm]; pubis [front part of the pelvis]; ilium [from the side of the pelvis]; femur or thigh bone; tibia or shin bone of the leg; metatarsal bones of the foot; vertebrae forming the back-bone and teeth’. Although the teeth appeared broken off close to the jaw, the jaw itself could not be traced. Some of the bones had features in common and seemed to belong together. Others were so broken and fragile they were impossible to identify. All the bones were hopelessly intermingled with debris from other animals, turtles, fishes, shells and vegetables.