DOI: 10.5061/dryad.qfttdz0km
title: Data from: Metamorphism as the cause of bone alteration in the Jarrow assemblage (Langsettian, Pennsylvanian) of Ireland

description: The Jarrow assemblage is a Lagerstätte of Pennsylvanian tetrapods and fish
 preserved in the Leinster Coalfield, Ireland. Fossils from this site have
 an interesting taphonomy that is not observed in other Pennsylvanian coal
 swamp assemblages. The bone material of the Jarrow tetrapods has undergone
 alteration and eventual coalification – causing specimens to become poorly
 defined from the surrounding coal matrix. Bone alteration at Jarrow has
 traditionally been linked to early diagenesis. Here a multi-analytical
 approach, combining X-ray scanning electron microscopy,
 cathodoluminescence, micro-computed tomography and laser ablation
 quadrupole inductively coupled plasma mass spectrometry, is used to
 investigate the origin of alteration within the Jarrow fossil specimens.
 Original bone morphology is no longer present, being replaced by
 bituminous material and sphalerite surrounded by tabular apatite (a
 morphology atypical of bone apatite). Direct U-Pb dating of this
 recrystallised apatite provides an age of 302 ± 11.4 Ma. In recrystallised
 apatite, zonation in halogen elements, variably positive and negative
 Eu-anomalies and depletion in LREE suggest an influence of hydrothermal
 fluids sourced during the maturation of the Leinster Coalfield. A new
 taphonomic model for the Jarrow assemblage is proposed: alteration of
 primary fossil bone occurred primarily due to burial heating of the
 Leinster Coalfield caused by Variscan deformation. Bone apatite was
 dissolved and then recrystalised as tabular crystals in a void followed by
 the mineralisation of sphalerite and bituminous material within the bone
 giving the Jarrow assemblage fossils their unique appearance.
description: <strong>SEM-EDX
 Data</strong> Osteoderms and a vertebra of
 <em>Ophiderpeton</em> <em>brownriggii</em>
 NMI.F16850 were mounted in epoxy resin and polished. These were then
 imaged using cathodoluminescence (CL) and analysed for major elements
 using SEM-EDX at the iCRAG laboratory, Trinity College Dublin. Analyses
 were carried out using a Tescan TIGER MIRA3 field emission SEM, equipped
 with two Oxford XMaxn 150 mm2 EDS detectors. The TIGER MIRA3 instrument
 utilizes the Oxford Instruments AZtec X-ray microanalysis software suite.
 The instrument was calibrated using appropriate mineral standards from the
 Smithsonian Institute (Jarosewich 2002; Jarosewich et al. 1980) following
 the method of Ubide et al. (2017). Analytical biases using this setup for
 CaO, P2O5, and F are typically &lt; 1% (O’Sullivan et al. 2021a;
 Ansberque et al. 2019; Ubide et al. 2017). For elemental Cl analysis, the
 instrument was calibrated using natural scapolite (meionite) NMNH R6600
 obtained from the Smithsonian Institute. Two quality control standards
 were used; a natural reference material fluorapatite, NMNH 10402
 (Jarosewich et al. 1980) and scapolite BB-1 (Kendrick 2012; Kendrick et
 al. 2013) to verify accuracy. The observed analytical biases for Cl
 analyses were &lt; 5 %. The detection limit for Cl utilizing this
 analytical setup is ~ 0.10 wt. %.
 <strong>LA-Q-ICPMS
 Data</strong> Apatite from the bone of
 <em>Ophiderpeton</em> <em>brownriggii</em>
 NMI.F16850 was also analysed by laser ablation quadrupole LA-Q-ICPMS at
 the iCRAG laboratory, Trinity College Dublin. The analytical setup
 utilized a Teledyne Photon Machines G2 laser-ablation system, comprising a
 193 nm ArF excimer laser and a Helex II active two-volume ablation cell,
 coupled to a Thermo Scientific iCAP Qc ICPMS. Analyses were conducted
 using a 35 µm diameter spot. The repetition rate was 15 Hz and an energy
 density of 1.6 J/cm<sup>2</sup> was used.
 <sup>43</sup>Ca was employed as the internal standard element,
 used to correct for mass bias during analysis. Data reduction used the
 Iolite software of Paton et al. (2011). For U-Pb geochronology the data
 reduction scheme VizualAge_UcomPbine (Chew et al. 2014; O’Sullivan et al.
 2021a) was used, which enables the use of primary standards with variable
 common Pb. It, in turn, is based upon the Vizual_Age data reduction scheme
 of Petrus and Kamber (2012). The analytical procedure for apatite U-Pb
 geochronology and trace element analysis used a standard-sample bracketing
 procedure. The primary reference material was Madagascar apatite (ID-TIMS
 U-Pb concordia age of 473 ± 0.7 Ma; Chew et al. (2014) and references
 therein). The secondary reference materials for U-Pb geochronology were
 Durango apatite (206Pb/238U age of 32.72 ± 0.07 Ma; Paul et al. 2021) and
 McClure Mountain apatite (weighted mean apatite 207Pb/235U age of 523.51 ±
 2.09 Ma; Schoene and Bowring 2006). For trace element analysis NIST612 was
 the primary standard employed, with Durango fluorapatite and McClure
 Mountain fluorapatite (values from Chew et al. 2016) employed as the
 secondary reference materials. U-Pb isotopes and trace elements were
 acquired simultaneously. In total, the analysed masses were:
 <sup>43</sup>Ca; <sup>51</sup>V;
 <sup>55</sup>Mn; <sup>88</sup>Sr;
 <sup>89</sup>Y; <sup>137</sup>Ba;
 <sup>139</sup>La; <sup>140</sup>Ce;
 <sup>141</sup>Pr; <sup>146</sup>Nd;
 <sup>147</sup>Sm; <sup>153</sup>Eu;
 <sup>157</sup>Gd; <sup>159</sup>Tb;
 <sup>163</sup>Dy; <sup>165</sup>Ho;
 <sup>166</sup>Er; <sup>169</sup>Tm;
 <sup>172</sup>Yb; <sup>175</sup>Lu;
 <sup>202</sup>Hg; <sup>204</sup>Pb;
 <sup>206</sup>Pb; <sup>207</sup>Pb;
 <sup>208</sup>Pb; <sup>232</sup>Th; and
 <sup>238</sup>U. Some elements were analysed only to detect
 inclusions in the laser spot; for example, V was measured to check the raw
 signal for the presence of pyrite inclusions within the analysed
 apatite. <strong>CT Data</strong>
 CT Data was obtained of
 NMI.F14879 <em>Ophiderpeton</em>
 <em>brownriggii</em> at the XTM Facility, Palaeobiology
 Research Group, University of Bristol using a Nikon XTH 225 ST. The
 specimens were scanned with the following parameters: kV225, µA with a
 10mm Cu filter. 3D models were rendered using
 SPIERS.
description: Files are either .xlsx, .csv, .tif or .stl. The former three can
 be read on most computers. .stl files can be viewed in most 3D viewing
 softwares including the freeware SPIERSview (https://spiers-software.org/)