Iguanodon is older than you think: The public and private announcements of Gideon Mantell’s giant prehistoric herbivorous reptile

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Martin I Simpson (UK)

The details of how the nineteenth century Sussex surgeon and palaeontologist Gideon Mantell came to acquire, describe and announce to the world a new fossil herbivorous reptile, later to be christened Iguanodon and to be included in Owen’s Dinosauria, have been merged together to form one of the most often quoted and legendary stories in the history of vertebrate palaeontology. However, the accuracy of some elements of the story has been questioned by recent scholars, for example, the role played by Gideon’s wife, Mary Ann. She has long been thought to have discovered the first teeth in a pile of road metal by the roadside, while her husband was attending one of his patients in Cuckfield. This is an event which is supposed to have occurred before 1822. In his book, The Fossils of the South Downs, published in that year, Gideon clearly states that Mary had found teeth, although the exact circumstances are not discussed.

Some of the teeth acquired by the Mantells were examined by Baron Cuvier. In June 1824, this famous French anatomist ultimately decided that they all belonged to a new and unknown herbivorous reptile. Inspired by this conclusion, Gideon visited the Huntarian Museum of the Royal College of Surgeons in the autumn of 1824 to hunt down a modern reptilian equivalent.

However, it was Samuel Stutchbury, not Gideon Mantell, who provided the next ‘light bulb’ moment by noticing a similarity between the teeth of the enigmatic fossil animal and those of a modern Iguana. Capitalising on this breakthrough, Mantell proposed the name Iguanasaurus in a letter to William Conybeare on the 13 November 1824. Conybeare, who had devised the name Megalosaurus, was suitably unimpressed with Gideon’s choice of generic name and proposed (on 24 November 1824) two possible alternatives: Iguanoides (‘like an Iguana’) or Iguanodon (‘having the tooth of the Iguana’). It is a matter of historical fact that Gideon chose the latter.

Up until now, it has always been believed that the first public announcement or description of the newly named Iguanodon was Mantell’s letter read at the Royal Society of London on the 10 February 1825. Not so. It transpires that Gideon Mantell sent a letter with the details of the discovery to the Portsmouth Philosophical Society in December 1824, only a matter of weeks after settling on Conybeare’s name Iguanodon. The contents of this letter were read at the meeting of Friday, 17 December. A report of this event was then published in The Hampshire Telegraph on Monday 20 December 1824. The new name was also published, but was spelt differently, as ‘Iguanadon’, thereby predating the Royal Society paper by over seven weeks. Biographers and scholars have been unaware of this 1824 reference, appearing in the previous calendar year, which is reproduced in full in Fig 1.

Fig 1. The extract from The Hampshire Telegraph and Sussex Chronicle, and General Advertiser for Hants, Sussex, Surrey, Dorset, and Wilts of 20 December 1824.

In a further twist, the occurrence of fossil reptile remains in the vicinity of Cuckfield does not necessarily seem to have been something uniquely discovered by the Mantells between 1817 and 1822. In fact, as early as 1813, the presence of the “bones and teeth of the alligator” in the fossil “congeries” (spoil heaps/piles of rock) around Cuckfield was reported by a correspondent, identified simply as JD, to a weekly Sussex newspaper (Sussex Advertiser of 5 April 1813). This was the Rev James Douglas, whose article would surely have been read by the Mantells. Gideon would go on to reap the full intellectual benefit several years later.

The 1824 article reproduced here in full is a fascinating and important addition to the Iguanodon story. To dinosaur scholars, it is important for two reasons. First, it is an earlier publication than the Royal Society paper, albeit with the name spelt incorrectly, and secondly, it demonstrates Mantell’s eagerness to publicise his new discovery as quickly as possible by using a provincial society and newspaper. Of course, the article in the Hampshire Telegraph does not constitute a proper scientific description, so the validity of the 1825 article is not under threat. However, it is undoubtedly an earlier published reference to the name, which therefore should be referred to in synonymies as follows:

Iguanadon, nomen nudum: Anon 1824. Hampshire Telegraph, 20 December, 1824.


Iguanadon, nomen nudum: Mantell in Anon 1824 (etc).

Fig. 2. A worn Iguanodon tooth similar to those found by Mantells.

About the author

Martin Simpson is a freelance palaeontologist living and working on the Isle of Wight. He specialises in the study of fossil lobsters and the history of palaeontology.

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