A Mastodon Named Leviathan: A Monster's History

Before it was a museum specimen, the Natural History Museum's American mastodon fossil toured the world as a monstrous “Leviathan.”

Tucked away in one of the Wonder Bays of the Natural History Museum’s Hintze Hall is a fossil with an unusually chaotic past. At first glance, it is simply an imposing skeleton of Mammut americanum, the American mastodon - the first of its kind ever to be reconstructed. But this specimen has had a far stranger life than most museum objects. Before it settled into scientific respectability, it spent time as a vast, impossible creature: a travelling monster known as the Missouri Leviathan.

Mastodons were prehistoric inhabitants of North America, relatives of mammoths and modern elephants, all part of the group of trunk-bearing mammals known as proboscideans. They lived until around 13,000 years ago, sharing the landscape with early humans, who likely contributed to their extinction. They differed from mammoths in key ways: not least in their teeth, which were adapted for browsing on twigs and leaves rather than grazing on grasses.

The Unknown Beast

The first recorded mastodon tooth was found in 1705 by a Dutch farmer in what would later become New York State. It weighed over two kilograms. More bones surfaced over the following decades: in 1739, French soldiers uncovered large fossil remains in Kentucky, which were sent to Paris. No one knew quite what they belonged to. The creature became known simply as the incognitum, ‘the unknown’.

Some believed these remains came from elephants that had somehow wandered across the Atlantic. Others thought they might be mammoths, like those found frozen in Siberia. It was only later that the anatomist Georges Cuvier proposed that they belonged to an entirely distinct and extinct species. He named them “mastodon,” after the distinctive, nipple-shaped cusps on their molars.

Even then, the creature was only partially understood—assembled from fragments, reports, and conjecture.

Enter the Showman

The mastodon that now stands in London passed through far less orderly hands before reaching the museum. It was acquired and reconstructed by Albert Koch, a German-born showman with a talent for turning natural curiosities into spectacle.

In 1840, Koch gained access to a site in Missouri containing numerous mastodon bones. Rather than reconstructing a single, accurate skeleton, he did something far more profitable. He combined remains from multiple animals, added extra ribs and vertebrae, extended the spine, and arranged the tusks so that they flared outward like horns. The result was a creature far larger and more terrifying than any mastodon that had ever lived: over nine metres long and more than four metres high.

He named it Leviathan, invoking the vast, biblical sea monster. The name did a great deal of work. It lent the creature religious weight, mythological depth, and an air of ancient authority. Koch reinforced the illusion with an elaborate backstory: the beast, he claimed, had been aquatic, using its tusks to hook onto trees at night like a ship at anchor. It was a detail that echoed older natural histories, much like the stories of walruses clinging to cliffs with their tusks.

The effect was extraordinary. Koch had not simply reconstructed an animal - he had made a monster.

Leviathan on Tour

The Leviathan became a sensation. Koch took it on tour across America and Europe, drawing large crowds and substantial profits. For many viewers, this was not a reconstruction but a revelation: a glimpse of a lost and monstrous world.

When the skeleton reached London in 1844, it caught the attention of Richard Owen, then superintendent of natural history at the British Museum. Owen immediately recognised its significance as a scientific object under the monstrous spectacle. He purchased it for a considerable sum: $2,000 upfront, plus $1,000 a year for the rest of Koch’s life - a commitment that proved expensive, as Koch lived for another twenty-two years.

Owen then faced the task of deconstructing the monster. He took apart Koch’s construction and painstakingly reassembled the bones into something resembling a real mastodon. This was no simple process. It required anatomical expertise, comparison with other specimens, and a degree of informed guesswork.

From Monster to Specimen

This skeleton’s journey - from scattered bones, to monstrous Leviathan, to scientific specimen – demonstrates how monsters are often built from real materials like bones, fragments and partial knowledge. What transforms them is interpretation, layered with imagination, belief, and spectacle.

In Koch’s hands, the mastodon became a myth, in Owen’s, it became a fact. But the boundary between them has never been entirely stable.

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If you enjoyed this, do check out my latest book, Enchanted Creatures: Our Monsters and their Meanings as well as my other writing.

Mastodon Leviathan History -- Copyright Natalie Lawrence 2026