The Dinosaur Hunters: A True Story of Scientific Rivalry and the Discovery of the Prehistoric World. Deborah Cadbury
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.
The only way he could begin to make sense of the puzzle was to distinguish the different types of teeth. There seemed to be two sets here that could not have come from the same species of animal. One set of teeth were blade-like and up to three inches long, flattened from side to side, with two sharp edges stretching from the crown. These edges were serrated like a steak knife, constructed for tearing flesh, not eating vegetables. The teeth could only have belonged to a carnivorous animal. And although he couldn’t prove it beyond doubt, Mantell was certain that they belonged to a giant reptile because they were more similar to crocodile teeth than anything he had seen at the Royal College of Surgeons. However, there were some crucial differences. Crocodile teeth are conical, slightly curved, the surface of the enamel covered with ridges radiating longitudinally from the tip to the crown. A crocodile grips its prey, and then flicks