Fossils that are more than 500 million years old and in an extraordinary state of preservation have revealed unknown details about trilobites, thanks to some specimens found in Morocco where, as if in Pompeii, they were suddenly buried by lava.
The hard calcified exoskeleton of the trilobites They are usually well preserved, which is why they are one of the marine animals fossils The best studied species are known, with more than 20,000 known species, but until now only a few soft tissues have been preserved.
A study published this Thursday in Science has also revealed that volcanic ash in shallow marine areas can be a favorable environment for the exceptional preservation of fossilsaccording to Greg Edgecombe, from the Natural History Museum in London and a signatory of the research.
Three-dimensional preservation
The trilobites from the Cambrian era found in Morocco were fossilized due to rapid burial in ash produced by a single pyroclastic flow event that devastated a shallow marine environment, according to the authors.
Once trapped, their bodies quickly fossilized as the ash transformed into rock, something similar to what happened to the inhabitants of Pompeii after the eruption of Vesuvius, which allowed three-dimensional preservation of both the exoskeleton and the soft anatomy.
The ash casts preserved every segment of the bodies, the legs, the hairy structures that ran along the appendages and even the digestive tract.
The study’s lead author, Abderrazak El Albani, a geologist at the University of Poitiers (France), said that pyroclastic deposits should become new targets of study, “given their exceptional potential to trap and preserve biological remains, including delicate soft tissues.”
Artist’s reconstruction of two species of trilobites just before they were buried in a volcanic ash flow 510 million years ago. | Source: EFE / A. El Albani (University of Poitiers)
The new specimens were studied with computed tomography and computer modeling of virtual X-ray sections, which allowed us to observe the articulated exoskeleton, antennae, postantennal appendages, digestive system and other soft tissues.
Unknown anatomical features
The researchers described previously unknown anatomical features, such as its novel feeding structures: a slit-like mouth opening and specialized appendages on the head that form a complex feeding apparatus around the mouth.
“The results revealed in exquisite detail a cluster of specialized pairs of legs around the mouth, giving us a clearer idea of how the trilobites”explained Harry Berks, from the University of Bristol (United Kingdom) and also author of the text.
Likewise, they discovered that the appendages of the head and body had a battery of dense spines facing inward, like those of modern horseshoe crabs.
(With information from EFE)
