Data from: Electron backscatter diffraction (EBSD) analysis of maniraptoran eggshells with important implications for microstructural and taphonomic interpretations

Electron backscatter diffraction (EBSD) is a useful tool for gathering crystallographic information from carbonate biominerals because it maps out the orientation of crystal grains very precisely. EBSD has become popular in invertebrate palaeontology but its application in vertebrate palaeontology remains limited. However, the study of fossil eggshells is a field where EBSD has wide potential applicability and provides a quantitative approach to fossil eggshell research as well as new qualitative data. Here we analyse fossil and extant maniraptoran dinosaur eggshells using EBSD analysis emphasizing four different aspects. The mapping imaging clarifies previously ambiguous characters such as squamatic ultrastructure and allows a more objective evaluation of avian and non‐avian maniraptoran eggshell. In particular, our results imply that the presence of an external zone in the manirpatoran eggshell is not diagnostic of avian eggshell. EBSD analysis can be also used for differentiating true pore canals from cracks in the eggshell radial section, thereby determining the biological genuineness or otherwise of a pore‐like structure. Finally, the misorientation angle distribution of the material shows a clear dichotomy that may reflect reproductive brooding strategy, although further studies on contact incubation of palaeognaths and neognaths are needed to confirm this.Fossil eggshell SEM imagesElongatoolithus sp., Prismatoolithus levis and Gobioolithus minor secondary electron images. Note rugged grain boundaries in continuous layers.Modern avian eggshell SEM imagesRhea, chicken, duck, Japanese tit, Korean magpie eggshells in secondary electron mode. Note rugged grain boundaries in continuous layers.EBSD raw data for materialsChannel 5 files. Note that in case of Gobioolithus minor, a version that diagenetic calcite is removed is used for misorientation histogram. In each species, a complete EBSD data and a subset for mammillary layer analysis are included. A zero solution corrected version is provided as raw data.Misorientation (For Figure 9)Misorientation angles for neighbour-pair (correlated) and random-pair (uncorrelated) distributions. These data were used for histograms in Figure 9.Misorientation (For Figure S2 and Table S2)Misorientation angles for neighbour-pair (correlated) and random-pair (uncorrelated) distributions. These data were used for histograms in Figure S2 and for Table S2.Contrast mapsContrast map of materials.10 Grain boundary mapsThese maps were used for measuring ruggedness of the grain boundaries in squamatic ultrastructure and an external layer.Supplementary Figures S1-S4Supplementary Figures cited in the text.Supplementary Tables S1-S3Supplementary Tables cited in the text.Raw data converted to Text filesThese are CRC files converted into text files for users who can not access CRC file