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 high speeds, such 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 onto which the ash flowed would have been deadly hot, and yes, it would have burned animals at its deepest depths,” said one of the study’s authors. 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.
It is about 508 million years old, younger than the oldest trilobites, which date back to about 521 million years ago. There is also an even older burrow-shaped trace fossil, called Rusophycus, which is thought to have been the work of trilobites and is 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 their proximal life orientations. Because they are preserved as empty space in the stony matrix, we can image them cross-sectionally to see them in 3D.”
Microscopic reconstruction of the trilobite Gigoutella mauretanica in ventral view.
Image source: © Arnaud Mazurier, IC2MP, Univ. Poitiers
“Appendices preserved in shale can hold their shape beautifully but the fossils are compressed to the point of being almost two-dimensional and we have to use demolition specimens to mechanically drill out the upper parts of the appendage 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 was published in the journal Sciences.
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