Minerals in the gut: scoping a Cambrian digestive system

Strang, K.M.; Armstrong, H.A.; Harper, D.A.T.

Abstract

The Sirius Passet Lagerstätte of North Greenland contains the first exceptionally preserved mat-ground community of the Cambrian, dominated, in terms of abundance, by trilobites but particularly characterized by iconic arthropods and lobopods, some also occurring in the Burgess shale. High-resolution photography, scanning electron imaging and elemental mapping have been carried out on a variety of specimens of the non-mineralized arthropod Campanamuta mantonae (Budd 2011 J. Syst. Palaeontol. 9, 217–260 (doi:10.1080/14772019.2010.492644)) which has three-dimensional gut and muscle preservation. Results show that the guts contain a high concentration of calcium phosphate (approximating to the mineral francolite), whereas the adjacent muscles are silicified. This indicates a unique, tissue-specific taphonomy for this Cambrian taxon. We hypothesize that the precipitation of calcium phosphate in the guts occurs rapidly after death by ‘crystal seed’ processes in suboxic, slightly acidic conditions; critically, the gut wall remained intact during precipitation. We postulate that the calcium phosphate was derived from ingested cellular material. Silicification of the muscles followed as the localized water chemistry became saturated in silica, high in Fe2+, and low in oxygen and sulfate. We document here the unique occurrence of two distinct but mechanistically similar taphonomic pathways within a diverse suite of possibilities in an Early Cambrian Lagerstätte.

Citation

Strang, K., Armstrong, H., & Harper, D. (2016). Minerals in the gut: scoping a Cambrian digestive system. Royal Society Open Science, 3(11), Article 160420. https://doi.org/10.1098/rsos.160420

• Journal Article Type: Article
• Acceptance Date: Oct 18, 2016
• Online Publication Date: Nov 16, 2016
• Publication Date: Nov 16, 2016
• Deposit Date: Nov 23, 2016
• Publicly Available Date: Nov 28, 2016
• Journal: Royal Society Open Science
• Electronic ISSN: 2054-5703
• Publisher: The Royal Society
• Peer Reviewed: Peer Reviewed
• Volume: 3
• Issue: 11
• Article Number: 160420
• DOI: https://doi.org/10.1098/rsos.160420
• Public URL: https://durham-repository.worktribe.com/output/1369736