The drawing looks like a jumble of bones. It’s an animal, a vertebrate, and we might now guess a dinosaur, but when it was discovered by dynamite, in a quarry in Tilgate Forest in 1832, that word did not exist.


Rough sketch by Gideon Mantell of a new discovery, in a letter to William Buckland (RS MS/251/49).


The rough sketch is from a letter by Gideon Mantell FRS, sent to William Buckland FRS and discussing his new discovery. What’s fascinating is Mantell’s ability to make sense of what he painstakingly extracted from the stone. Only two other giant reptiles had been described before this one, the Iguanodon by Mantell himself and Megalosaurus by Buckland.

The son of a shoemaker, Mantell went into medicine as an apprentice. He was aided by his understanding of anatomy and study of the natural world, but hindered by his need to work on his fossils alongside a busy medical practice. Mantell’s understanding of the stratigraphy of the Weald meant he knew the layers of rock containing Iguanodon came from a time before mammals, and the teeth he and his wife Mary Ann found were from a huge herbivore, unlike anything alive today.


Iguanodon teeth, from Philosophical Transactions of the Royal Society, Vol.115 (1825), p.186, plate XIV (RS IM/000536)






















Mantell struggled for a number of years to have the contemporary luminaries of geology accept his evidence. They believed the rocks were not as old as he thought, and the teeth were of a mammalian herbivore. His persistence and ability to interpret fossils led to acceptance of his view, recognition that he’d found a giant herbivorous reptile, his election as Fellow of the Royal Society in 1825, and the award of the Society’s Royal Medal in 1849.


Mantell’s election certificate, signed by some of the most important men in the field of geology, now persuaded by his discoveries (RS EC/1825/08).


However, the jumbled dinosaur is not an Iguanodon. It’s a creature I find much more exciting – Hylaeosaurus armatus, a type of Ankylosaur. Like many dinosaurs, this fossil is the only Hylaeosaurus to be securely identified, and is not complete, but Mantell understood its main distinguishing feature: this dinosaur was armoured. In The Geology of the South-East of England, he writes: ‘there appears every reason to conclude that either its back was armed with a formidable row of spines, constituting a dermal fringe, or that its tail possessed the same appendage, and was enormously disproportionate to the size of the body … the specific name armatus, in either case, would not be inappropriate.’


Lithograph from ‘The wonders of geology’, 1840. A jumble of bones, but Mantell was able to understand the distinctive nature of Hylaeosaurus armatus.


Bony plates and spines cover the bodies of these dinosaurs from head to tail. It’s a Cretaceous tank. Ankylosaurs were a highly successful group, roaming every continent including Antarctica, a type of dinosaur it really took an asteroid to kill. Although we haven’t found another Hylaeosaurus, there have been exciting discoveries of closely related animals. In 2011 a Nodosaur, a sister group of armoured dinosaurs who lack the clubbed tail of Ankylosaurs, was excavated with armour in position, preserved skin and signs of red pigment. Discoveries like this help root imagination ever more securely in reality, our view of the geological past coming more sharply into focus.

Gideon Mantell could look at the Hylaeosaurus and other fossils from the Weald and imagine a vanished world. At the same time as Mary Anning was discovering marine reptiles of a petrified Jurassic ocean, the fossils Mantell examined revealed the freshwater and tropical land of Cretaceous England, a hot river delta with exotic palms and ferns.


Portrait of Gideon Mantell by John James Masquerier, 1837 (RS P/0087).


Despite his successes, Mantell’s life was marred by tragedy. Financial difficulties led him in 1838 to sell his entire collection of fossils to the British Museum, including Hylaeosaurus. His wife left him in 1839, in 1840 his daughter Hannah died, and a horrific carriage accident on 11 October 1841 left him with a damaged spine and suffering chronic pain. On 10 November 1852 he died of an overdose of opium.

The dark shadow continues after his death. A vicious, anonymous obituary was published in the Literary Gazette, widely attributed to Richard Owen, long his rival. Mantell’s spine, severely curved with scoliosis, was preserved as a specimen at the Hunterian Museum, where Owen was the curator. Some have seen this as a macabre act of revenge on the part of Owen, while others have said it was something Mantell suggested himself in his will.

The will included a £10 provision for a post-mortem, but there is no mention of sending anything discovered to the Hunterian collection, although it is possible such a request exists in another document. The rivalry between the two scientists is itself a source of fascination, explored in Deborah Cadbury’s book The Dinosaur Hunters and the recent play Dinomania.


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