The most detailed reconstruction of Cambrian trilobites has been achieved

Thanks to their rapid entombment in volcanic ash in a process similar to that of Pompeii, the anatomy of Cambrian-era trilobites is more discernible than ever before thanks to exquisitely preserved fossils.

These fossils, discovered in Morocco, are scientifically described in a new study that reveals microscopic details, including the trilobites’ appendages and digestive system.

Trilobites are perhaps the best-known of all the creatures that lived during the Cambrian period. The hard exoskeleton of these extinct marine arthropods favors their high fossilization potential, facilitating the identification of more than 22,000 trilobite species and a robust fossil record spanning from the early Cambrian to the Permian extinction event.

Although this abundance of fossils has led to a great knowledge of the external morphology of these animals, knowledge of their anatomy, particularly their soft tissue appendages and internal organs, which are rarely preserved, has been very limited.

In the new study, Abderrazzak El Albani and Arnaud Mazurier of the University of Poitiers in France and their colleagues have delved deeper into several exceptionally well-preserved and anatomically complete Cambrian-era trilobite fossils from the Tatelt Formation in Morocco.

According to El Albani, Mazurier and their colleagues, the trilobites were fossilized due to rapid burial in ash produced by a single pyroclastic flow event that devastated a shallow marine environment.

This scenario led to their being buried instantly and enjoying pristine, three-dimensional preservation of both the exoskeleton and the soft anatomy it contained.

Using microtomographic X-ray images, the study’s authors were able to observe anatomical features including the trilobites’ articulated, undistorted exoskeleton, antennae, postantennal appendages, digestive system, and other soft tissues.

El Albani, Mazurier and their colleagues also describe previously unknown anatomical features, such as its striking feeding structures, a slit-like mouth opening and specialized appendages on the head that form a complex feeding apparatus around the mouth.

Microtomographic reconstruction of the head and adjacent parts of one of the trilobite specimens investigated. (Image: © Arnaud Mazurier, IC2MP, Univ. Poitiers)

Furthermore, the findings suggest that other volcanic ash deposits in marine environments, such as the one that entombed the Tatelt trilobites, may have significant potential for preserving soft-bodied creatures or finely detailed anatomy, highlighting the potential for future discoveries at similar deposits.

The study is titled “Rapid volcanic ash entombment reveals the 3D anatomy of Cambrian trilobites.” It has been published in the academic journal Science. (Source: AAAS)