A palaeontological Pompeii

For the first time in history, palaeontologists have been given a complete glimpse of trilobite anatomy, thanks to a collection of ancient fossils that have been frozen in time by volcanic ash.

Similar to the bodies of the humans and animals found at the archaeological site of Pompeii, these rare specimens have been preserved as complete three-dimensional moulds in fine volcanic ash, resulting in the most anatomically complete trilobite fossils ever discovered.

UNE palaeontologist, Professor John Paterson, co-led the investigation of this astounding discovery which has been published in Science , and says it paints the clearest picture we've ever seen of these ancient marine creatures.

Trilobites are extinct marine arthropods-the animal group comprising of insects, crabs and spiders-that lived in the world's oceans between 521 and 252 million years ago.

"These particular trilobites from Morocco are from the Cambrian Period and about 509 million years old, making them some of the oldest known," he says.

"The vast majority of trilobite fossils consist only of hard body parts, such as the mineralised exoskeleton, but these exceptional examples also preserve the soft parts, including the antennae, walking legs, mouth structures, and even the entire digestive system! This can tell us a lot about the biology and lifestyles of these ancient critters."

Until now, scientists' understanding of trilobite 'soft' body parts, such as the elements that make up the mouth, has been largely hypothetical.

"This has been frustrating, as knowing how such mouth structures evolved is important for understanding how different arthropod groups are related to one another," says Professor Paterson.

"These fossils now give palaeontologists a 'search image' to look for such features in newly-collected trilobite specimens, or perhaps those sitting in museum drawers."

The violent nature of volcanic eruptions can provide the ideal conditions for fossil preservation, as they produce high-speed clouds of ash that can cover vast areas, including marine settings, in a very short amount of time.

"Such an event would have rapidly buried these trilobites that were living in shallow waters near the shoreline, with the volcanic ash quickly moulding and cementing these animals in place," says Professor Paterson.

"This entombment must have been almost instantaneous, as we also find filter-feeding animals called brachiopods attached to these trilobites in life position, capturing a symbiotic relationship 'snap frozen' in time."

Science is one of the world's most prestigious journals and only a very small percentage of submitted papers are accepted for publication. Professor Paterson's involvement is just another reflection of UNE's strong capability in the Earth Sciences, demonstrating that the work being undertaken at UNE's Palaeoscience Research Centre is world-class and at the forefront of palaeontological research.

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