'Monstrous' mastodon molar
This fossilised mastodon tooth from Norfolk once belonged to William Smith, who in 1815 produced the first ever geological map of Britain.
In the same year as this tremendous achievement, financial problems led Smith to sell his precious fossil collection to the British Museum. The collection moved to South Kensington in 1881 when the Natural History Museum was built.
To catalogue this collection Smith published 'Strata Identified by Organized Fossils, Containing Prints on Colored Paper of the Most Characteristic Specimens in Each Stratum', where he also explained the theories that enabled him to map Britain's underlying geology.
Recognising this fossil tooth as something special, Smith used it for the frontispiece of his book. While we now know it came from the mastodon Anancus arvernensis, Smith only knew that it belonged to 'some extinct monstrous unknown animal'.
The hand-coloured engraving and Smith's accompanying description make it the first documented example of a mastodon fossil from Britain.
Museum palaeobiologist Professor Adrian Lister tells us:
'We know that this fossil tooth is at least two million years old, because we haven't had mastodons in Britain since then.
'It is a fantastic, almost complete specimen of an upper molar. We can see that the back of the tooth hadn't yet erupted, while the front half is worn down from chewing food.'
The shape of the tooth tells us a bit about the mastodon's diet, he adds:
'It indicates the animal ate a mixture of bark, leaves and grass. Their close relatives mammoths, in comparison, ate a more abrasive diet of mainly grass and evolved teeth with narrow ridges adapted for grinding and taller crowns that took longer to wear down.'
Although Smith collected various fossils of large vertebrates, such as this mastodon tooth and an Iguanodon leg bone, they were unusual finds and not helpful for identifying rock layers (strata).
Smith was most interested in fossils that were common and widely distributed, as they enabled him to identify and map equivalent strata across large swathes of land. These fossils were often invertebrates, such as ammonites. Some vertebrate fossils are abundant enough to be useful, however. For example, shark teeth are common in chalk layers.