Figure 5 : EBSD analysis of Mongolian and French eggshells.

From: Isotopic ordering in eggshells reflects body temperatures and suggests differing thermophysiology in two Cretaceous dinosaurs

Figure 5

Images are representative of multiple specimens examined. Colour coding is as described in Fig. 4. (ac,df) Two different individual Mongolian Oviraptorid eggshells, respectively. Both eggshells show an overall good preservation, with no evidence for recrystallization and calcite crystals displaying a preferred crystallographic orientation of the c axis perpendicular to the shell exterior, as shown in pole figures. In this respect, data are similar to Auca Mahuevo layer-4 eggshells in Fig. 4. There are some indications of deformation of calcite crystals, possibly due to eggshells being compressed on burial, as indicated discontinuity and deformation of crystal boundaries as seen in diffraction maps and a larger spreading of poles on the projection of the {0001} plane of calcite than typically observed in modern eggshells. For comparison, the bottom panels (gi) show data from a Rousset level-A eggshell that is completely altered and recrystallized, with none of the original microstructure typical of eggshells observed. Instead, the eggshell has been replaced by microcrystalline calcite with low diffraction, and the pole figure (i) shows the absence of biological control over crystallographic orientation.