Rapid volcanic ash entombment reveals the 3D anatomy of Cambrian trilobites

Abderrazak El Albani*, Arnaud Mazurier, Gregory D Edgecombe, Abdelfattah Azizi, Asmaa El Bakhouch, Harry O Berks, El Hafid Bouougri, Ibtissam Chraiki, Philip C J Donoghue, Claude Fontaine, Robert Gaines, Mohamed Ghnahalla, Alain Meunier, Alain Trentesaux, John Paterson*

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

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Knowledge of Cambrian animal anatomy is limited by preservational processes that result in compaction, size bias, and incompleteness. We document pristine three-dimensional anatomy of trilobites fossilized via rapid ash burial from a pyroclastic flow entering a shallow marine environment. Cambrian ellipsocephaloid trilobites from Morocco are articulated and undistorted, revealing exquisite details of the appendages and digestive system. Previously unknown anatomy includes a soft-tissue labrum attached to the hypostome, a slit-like mouth, and unique cephalic feeding appendages. Our findings resolve controversy over whether the trilobite hypostome is the labrum or incorporates it and establish crown-group euarthropod homologies in trilobites. This occurrence of moldic fossils with three-dimensional soft parts highlights volcanic ash deposits in marine settings as an underexplored source for exceptionally preserved organisms.
Original languageEnglish
Pages (from-to)1429-1435
Number of pages7
Issue number6703
Publication statusPublished - 28 Jun 2024


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