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Rare tooth from 55-million-year-old predator uncovered by seven-year-old boy
A molar found in sand from south London could shed light on the last days of an ancient mammal.
The fossil is from the weasel-like animal known as Prototomus, a meat-eater so old that it predates modern carnivores.
When Fiona and James Okai first approached the Natural History Museum’s stand at the Lyme Regis Fossil Festival, they had no idea they would find something truly special.
As part of a regular offering at the annual event, scientists were giving visitors the chance to sift through sand from Abbey Wood in southeast London in the hunt for tiny fossils. The site is renowned for ancient remains from the start of the Eocene, a time when many modern mammal lineages have their origins.
After searching through a cup of sand, James, who lives near Wareham in Dorset, had found plenty of shells and other fossils to take home. But there was one tooth that he, Fiona and the scientists on the stall couldn’t immediately identify.
“Looking for fossils is a really fun thing to do,” James says, “I enjoyed knowing that if I found something I liked I got to take it home.”
“My favourite things were the animal teeth. I found lots of shark teeth and the mammal tooth. It was weird to come across the mammal tooth because it had so many points on it and I didn’t know what it was.”
This is where Dr Neil Adams, the Curator of Fossil Mammals at the Natural History Museum, stepped in. He was able to identify the find, which was donated to the museum, as a rare fossil tooth from an ancient animal called Prototomus. This small predator lived more than 55 million years ago, and its remains can reveal what life was like at the time.
“These fossils are pretty rare, and there’s only a handful of Prototomus remains in our collections,” Neil says. “It’s a very nice find, as we don’t know a lot about this animal.”
“Even though it’s just a single tooth, studying the dental microwear on it could reveal more about the last days to weeks of the animal’s life, and what it was eating. Not a lot of this microwear research has been done on early Eocene mammals, especially the carnivores, so I think there’s a lot of interesting work to come.”
Eocene fossils are regularly found in Abbey Wood, where the remains of a 55-million-year-old ocean lie close to the surface. © creativecherry /shutterstock.
Abbey Wood – South London’s fossil hotspot
Just past the end of the Elizabeth Line station to which it lends its name, Abbey Wood is already renowned for the ruins of the historic Lesnes Abbey. But for palaeontologists, the real appeal is found deeper in the forest, where the remnants of an ancient sea are found just beneath the surface.
“55 million years ago, this area would have been at the bottom of a shallow sea, with tropical forests along its shores,” Neil explains. “When animals living in the sea died, their remains sunk to the bottom and were buried, turning into fossils over millions of years.”
“Abbey Wood is a very special site as it’s from the earliest part of the Eocene, known as the Ypresian. It’s one of the richest for fossils in all of northwest Europe, containing not just shells and shark teeth but also reptile, bird and mammal fossils.”
The remains of these land-living animals were likely washed into the sea from its shores or down nearby rivers. This means that the remains were often broken up, with teeth now the most common finds.
“Teeth are the most common mammal fossils from Abbey Wood as they are very durable. They’re often from animals like early horses, and those from carnivores are quite rare,” Neil says. “However, you do get some well-preserved bones as well.”
“We have an impressively complete skull from a mesonychid called Pachyaena, one of the larger predators of the era, in the fossil mammal collections from Abbey Wood.”
This new tooth is from a mammal called Prototomus, which belonged to a group of animals known as the hyaenodonts. It would have been about the size of a weasel or mongoose, and probably had quite a similar lifestyle as it likely hunted rodents, birds and other small animals.
This was quite small compared to other hyaenodonts, with later relatives like Hyaenodon growing to about as big as a wolf. But by studying Prototomus, researchers hope to get a better idea of how this size transition occurred.
“Teeth are a mammal palaeontologists’ best friend, and there’s a lot they can tell us,” Neil explains. “Studying this tooth might give us a better understanding of the relationships between different hyaenodont species, and provide insights into the evolution of the group.”
Later relatives of Prototomus, like Hyaenodon, were significantly larger. © Danny Ye /shutterstock.
More to come?
While scientists consider what the Prototomus tooth might reveal, work continues at Abbey Wood. Three of the Natural History Museum’s Scientific Associates, Jerry Hooker and David and Alison Ward, lead regular digs at the site as they investigate Europe’s Eocene past.
Over the years, they have excavated hundreds of kilogrammes of sand for study, with much of it sorted through by members of the public at the Lyme Regis Fossil Festival. The work of these volunteers is invaluable to the researchers. In 2024 alone, over 500 people sorted through more than 210 kilogrammes of sand from Abbey Wood.
But even with all this help the sorting is a long process. The sand that the Prototomus tooth was found in, for example, was initially dug up in 2019. Neil is hopeful that as the work continues more interesting discoveries await.
“Abbey Wood is such a rich site, so it’s very possible that there could be many more important fossils to find,” he says. “It’s very possible we might even find more remains from the same Prototomus, as you can sometimes find teeth that slot into a previously discovered jawbone found by somebody else!”
“It’ll be worth keeping an eye out for anything that might fit the bill as we continue to discover more from this amazing locality.”
