DOI: 10.5061/dryad.sr34t33
title: Data from: Exceptional preservation requires fast biodegradation: thylacocephalan specimens from La Voulte‐sur‐Rhône (Callovian, Jurassic, France)

description: Konservat-Lagerstätten are seen as snapshots of past biodiversity for a
 given location and time. Yet, processes leading to the exceptional
 morphological preservation of fossils in these deposits remain
 incompletely understood. This results in the deficient assessment of
 taphonomic biases and limits the robustness/relevance of palaeobiological
 reconstructions. Here, we report the mineralogical characterization of
 crustacean fossils preserved within carbonate-rich concretions from the
 Jurassic Konservat-Lagerstätte of La Voulte-sur-Rhône (Ardèche, France).
 The combination of SEM-EDS, TEM, synchrotron-based XRF, XRD and XANES
 allows identifying the mineralogical phases composing these fossils (i.e.
 fluorapatite, Fe-sulfides (pyrite, pyrrhotite) and Mg-calcite) and the
 surrounding matrix (i.e. Mg-calcite, clays and detrital silicates).
 Fluorapatite and pyrite (and pyrrhotite) precipitated during decay under
 anoxic conditions, replacing delicate organic structures and preserving
 anatomical details. These mineral structures were subsequently
 consolidated by a Mg-calcite cement. Of note, histologically similar
 tissues were replaced by the same mineral phases, confirming that
 ‘fossilization [in La Voulte] occurred rapidly enough to be influenced by
 tissue composition’. Altogether, the present study shows that exceptional
 preservation requires fast biodegradation, thereby confirming recent
 experimental evidence.
description: .bcf
 and .rtb files are proprietary files from Bruker, containing SEM-EDXS
 hypermaps. These files can be opened either using the Esprit software from
 Bruker, or the Hyperspy suite developped for Python (free).
 The association of .hdr and .xim files are XANES stacks. They can
 be opened and treated with the aXis2000 software (free), specificallly
 developed and used at the majority of synchrotron beamlines producing such
 data. Before viewing the data, the stack needs to be aligned.
 Brief descriptions of the files are below, and further details
 are included in the associated README files. All descriptive information
 is also available in the FileTypes.txt document. MNHN.F.A70114_thinsection_FIB Thin section image and localisation of FIB foil extraction, specimen MNHN.F.A70114 Fig-4-A-D-G EDXS Hypermap, raw data (Bruker file) of specimen MNHN.F.R06054.03. Fig. 4A, D and G Fig-4-B-E-G EDXS Hypermap, raw data (Bruker file) of specimen MNHN.F.R06054.03. Fig. B, E and G. Fig-4-C-F-G EDXS Hypermap, raw data (Bruker file) of specimen MNHN.F.A70114 Fig. C, F and G. Fig-5-A-B_stack_XRF_slider Fig. 5 A-B Synchrotron X-ray fluorescence major-to-trace elemental mapping collected at the DiffAbs beamline, SOLEIL synchrotron. Acquisition parameters: 18 keV excitation energy; 75×75 µm2 scan step; 108,889 pixels; 150 ms counting time per pixel. Specimen MNHN.F.A66910. For further information, see README_for_Fig-5-A-B_stack_XRF_slider.txt Fig-5-C-D_stack_XRF_slider Fig. 5 C-D Synchrotron X-ray fluorescence major-to-trace elemental mapping collected at the DiffAbs beamline, SOLEIL synchrotron. Acquisition parameters: 18.2 keV excitation energy; 50×50 µm2 scan step; 356,942 pixels; 31.5 ms counting time per pixel. Specimen MNHN.F.R06054.03. For further information, see README_for_Fig-5-C-D_stack_XRF_slider.txt Fig-6-B-C_stack_XRD_slider Synchrotron X-ray diffraction mapping collected at the DiffAbs beamline, SOLEIL synchrotron. Acquisition parameters: 18 keV excitation energy; 75×75 µm2 scan step; 108,889 pixels; 180 ms counting time per pixel. Specimen MNHN.F.A66910. For further information, see README_for_Fig-6-B-C_stack_XRD_slider.txt Fig-6-D_stack_XRD_slider Fig. 6 D Synchrotron X-ray diffraction mapping collected at the DiffAbs beamline, SOLEIL synchrotron. Acquisition parameters: 18.2 keV excitation energy; 50×50 µm2 scan step; 356,942 pixels; 22.5 ms counting time per pixel. MNHN.F.R06054.03. For further information, see README_for_Fig-6-D_stack_XRD_slider.txt Fig-6-A-diff1_TwoTh_SUM Sum diffractogram (from XRD mapping data acquired on the HERMES beamline, SOLEIL synchrotron) presented in Fig. 6A, MNHN.F.R06054.03 section. Raw data. 2theta values at the synchrotron energy. Fig-6-A-diff1_TwoTh_SUM_despiked Sum diffractogram (from XRD mapping data acquired on the HERMES beamline, SOLEIL synchrotron) presented in Fig. 6A, MNHN.F.R06054.03 section. Treated – artifacts removed. 2theta values at the synchrotron energy. Fig-6-A-diff2_TwoTh_SUM Sum diffractogram (from XRD mapping data acquired on the HERMES beamline, SOLEIL synchrotron) presented in Fig. 6A, MNHN.F.A66910 section. Treated – artifacts removed. 2theta values at the synchrotron energy. Fig-7-A Raw Ca-XANES (STXM stack) data figured in Fig. 7A. Can be opened with the aXis2000 software.