Melksham Monster: Prehistoric Crocodile Pushes Back Reptile Family Tree Branch Millions of Years

The Melksham Monster would have looked pretty similar to this relative. Fabio Manucci

No one likes visiting the dentist for a cleaning—but at least your teeth didn't sit unbrushed for 163 million years. Not so for a fossil now nicknamed the Melksham Monster, which found its way to London's Natural History Museum in 1875, where it sat mostly unexamined until 2013.

That's when fossil preparator Mark Graham and his dental tools stepped into the picture. Armed with chisels tipped in carbon steel and industrial diamond grinders, he was able to chip away at the rock that enveloped the Melksham Monster's teeth as it fossilized.

What he uncovered, according to a new paper published in the Journal of Systematic Paleontology, was evidence of a new species—and that crocodiles are millions of years older than scientists had realized. "It's not the prettiest fossil in the world, but the Melksham Monster tells us a very important story about the evolution of these ancient crocodiles and how they became the apex predators in their ecosystem," lead author and doctoral student at Edinburgh University Davide Foffa said in a press release.

More formally known as Ieldraan melkshamensis, the Melksham Monster is named after the town in England near where it was first dug up, almost three hours's drive west of London in a geologic layer called the Oxford Clay Formation.

Between the creature's death and the team's new discovery, the Melksham Monster fell on rough times. All that remains is its skull, and even that has seen better days—the skull itself has been squished, some of the bones have been broken, and it has lost some of its teeth. "This was one tough old croc in life and death!" preparator Mark Graham said in a press release.

Modern tools offered a new chance to remove the rock-hard coating and let paleontologists take a new look at the skull. Lead author Foffa took the opportunity to compare it to other similar fossils. According to that comparison, the Melksham Monster is a new species, and its discovery means that the Geosaurini group of prehistoric crocodiles to which it belongs is older than scientists had previously realized.

At the time the creature would have lived, the rock now found in England was farther south and likely covered by warm shallow water full of squid-like animals and a range of other marine reptiles. Those squid-like animals would have been a key prey for the Melksham Monster, which would have snagged them with its unusual pointy teeth with grooves running along their length—the very same feature that helped confirm it was a new species.