Micro-computed x-ray tomography (MicroCT)
MicroCT (Zeiss) was used to determine the radii of pores and their geometry. Nine eggshell fragments (from the four species ofApteryx ) were used. The fragments were manually broken into three smaller fragments each, and a full scan of each fragment was used to observe the pore geometry. Images were obtained at 45Kj, 133 μA, 6 W; a source distance of 20 mm, detector distance at 8 mm, pixel size of 1.9266 μm, objective magnification 10X, exposure time 11 seconds, and 1,000 projection images through 180˚ of rotation. The images were analysed using Xradia mxct software. Images from the cuticle of all individuals were taken to see its physical features.
The pores of each fragment were counted, and their individual radii measured at three points along the pore, near the external opening, mid-way and close to the mammillary layer, these measurements were averaged to produce a mean pore radius.