508-million-year-old trilobite fossils from Pompeii show features never seen before

Trilobites dating back 508 million years have been found preserved in volcanic material, revealing unprecedented detail in 3D. They fossilized so quickly 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 meters (656 feet) per second. It usually burns any living things in its path, but this may change in the marine environment.

“The sea surface over which the ash flowed would have been lethally hot, and would have burned animals at shallow depths,” says the study co-author. Dr. Greg Edgecombe From the Natural History Museum, London, to IFLScience. “The ash likely mixed with seawater during its capture and trapping of trilobites that lived on the sea floor. This mixing in a column of seawater must have cooled the ash sufficiently.”

These ancient wonders were collected in the Atlas of Morocco, and were given the name “Pompeii” trilobites due to their exquisite preservation in ash. They’re incredibly old, but they’re not the oldest trilobites ever found.

At about 508 million years old, they are 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 ones, is the preservation of their appendages in 3D,” 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 3D.”

“Appendages preserved in shale can preserve their bristles beautifully, but the fossils are so compressed that they are almost two-dimensional, and we have to use destructive sampling to mechanically drill out the upper parts of the appendages in order to see the lower parts. Our specimens are as perfect after study as they were.” before.”

These never-before-seen details mean we’re now seeing trilobites that are closer to life than we’ve ever seen them before, complete with a slit-like mouth and unique vertical feeding appendages. Isn’t that beautiful?

The study is published in the journal Sciences.