'Pompeii-like' fossils found in Morocco reveal new details of 500 million-year-old species

Trilobites are among 'best-preserved three-dimensional fossils ever discovered'

An artist's image of two species of trilobite an instant before being buried in volcanic ash 510 million years ago. Photo: Prof A El Albani, University of Poitiers

“Pompeii-like” fossils have been discovered in the High Atlas mountain range in Morocco, providing new insights into a species that lived 500 million years ago.

Scientists say the trilobites, which date from the Cambrian period, are among the best-preserved three-dimensional fossils ever discovered. Trilobites are extinct marine invertebrates.

Because the Moroccan trilobites were encased in hot ash in seawater, their bodies fossilised quickly as the ash transformed to rock – meeting a similar end to the inhabitants of Pompeii following the eruption of Mount Vesuvius.

The ash moulds preserved every part of their bodies, including the hairlike structures that ran along the antennae. Even the trilobites’ digestive tracts were preserved after they filled with ash.

Dr Greg Edgecombe, a palaeontologist at London's Natural History Museum and member of the international team studying the fossils, said the discovery suggests volcanic ash in shallow marine settings could provide a rich source for other well-preserved fossils.

“I’ve been studying trilobites for nearly 40 years, but I never felt like I was looking at live animals as much as I have with these ones. I’ve seen a lot of soft anatomy of trilobites, but it’s the 3D preservation here that is truly astounding,” he said.

“An unexpected outcome of our work is discovering that volcanic ash in shallow marine settings could be a bonanza for exceptional fossil preservation.”

Trilobites are often among the best preserved, and studied, fossils due to their hard, calcified exoskeletons. More than 20,000 species have been described over the past two centuries.

But a full understanding about the group, which first appeared around 521 million years ago and lived for 300 million years, was limited by the relative scarcity of soft tissue preservation.

Lead author Prof Abderrazak El Albani, said: “As a scientist who has worked on fossils from different ages and locations, discovering fossils in such a remarkable state of preservation within a volcanic setting was a profoundly exhilarating experience for me.”

Microtomographic reconstruction of a trilobite. Photo: Arnaud Mazurier, IC2MP, University of Poitiers

The findings are anticipated to lead to significant discoveries about the evolution of life on our planet, he added.

Co-author Harry Berks, from the University of Bristol, said the results reveal “in exquisite detail” a clustering of specialised leg pairs around the trilobite's mouth, giving us a clearer picture of how it fed.

“The head and body appendages were found to have an inward-facing battery of dense spines, like those of today’s horseshoe crabs,” he added.

The paper was published online in the journal Science.