A micro X-ray computed tomography dataset of fossil echinoderms in an ancient obrution bed: a robust method for taphonomic and palaeoecologic analyses.

Background: Taphonomic and palaeoecologic studies of obrution beds often employ conventional methods of investigation such as physical removal and extraction of fossils from their host rock (matrix) by mechanical preparation. This often-destructive method is not suitable for studying mould fossils, which are voids left in host rocks due to dissolution of the original organism in post-depositional processes.

Findings: Micro computed tomography (µCT) scan data of 24 fossiliferous rock samples revealed thousands of Palaeozoic echinoderms, and digitally "stitching" together individually µCT scanned rock samples within 3D space allows for quantifiable taphonomic data on a fossil echinoderm-rich obrution deposit from the Devonian (Emsian) of South Africa. A brief step-by-step guide is provided on creating, segmenting and ultimately combining sections of richly fossiliferous beds to create virtual models suited for the quantitative and qualitative taphonomic analyses of fossil invertebrate assemblages.

Conclusions: Visualizing the internal features of fossiliferous beds in 3D is an invaluable taphonomic tool for analysing delicate fossils, accounting for all specimens irrespective of their preservation stages and with minimal damage. This technique is particularly useful for analysing fossiliferous deposits with mould fossils that prove to be difficult to study with traditional methods, because the method relies on the large density contrast between the mould and host rock.