Pompeii trilobite fossils dating back 508 million years show features never seen before

A 508-million-year-old trilobite has been found preserved in volcanic material, revealing unprecedented detail in 3D. Its fossilization was so rapid that tiny shells were preserved in place, and soft tissue including mouthparts and internal organs can still be seen.

The trilobites were buried in lava flows, the hot, dense material that erupts from volcanoes and sometimes reaches speeds as high as 200 m (656 ft) In the second. Normally, it burns any life in its path, but this can change in the marine environment.

“The sea surface onto which the ash flowed would have been deadly hot, and yes, it would have burned animals at its deepest depths,” one of the study’s authors said. Dr. Greg Edgecombe “The ash must have mixed with seawater as it picked up and carried the trilobites that lived on the sea floor. This mixing through the seawater column must have cooled the ash sufficiently,” the archaeologist at London’s Natural History Museum told IFLScience.

The ancient wonders, collected in the High Atlas of Morocco, have been dubbed the “Pompeii” trilobites because of their remarkable preservation in the ash. They are incredibly old, but they are not the oldest trilobites ever found.

They are about 508 million years old, younger than the oldest trilobites, which date back to about 521 million years ago. There are also older burrow-shaped trace fossils, called Rusophycus, which are believed to be the work of trilobites and are over 528 million years old.

However, the grouper fish is still remarkable in the degree of preservation it shows.

“What makes our specimens unique, especially pristine, is the preservation of their three-dimensional appendages,” Edgecombe continued. “The appendages are not flattened, reoriented or broken. They are preserved in the orientations of near-life. And because they are preserved as empty space in the rock matrix, we can image them in tomography to see them in three dimensions.”

“Appendages preserved in shale can preserve their shape beautifully but the fossils are so compact that they are almost two-dimensional and we have to use destructive samples to mechanically coring the upper parts of the appendage in order to see the lower parts. Our samples are as perfect after study as they were before.

These never-before-seen details mean we now see trilobites closer to real life than we’ve ever seen them before, complete with a slit-like mouth and unique vertical feeding appendages. Is not she beautiful?

The study is published in the journal Sciences.