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.