XPL images for normal (a) and purple stained (b) samples at equivalent stages of the extinction cycle. The normal sample shows a more ordered structure than the purple stained sample, along with a typical birefringence pattern. The extinction zones in the purple stained sample are very disorganized. The birefringence pattern is very disordered. There is also evidence of taphonomic cracking within the section. This indicates that the process responsible for unusual coloration affects the internal structure of the bone without affecting the gross morphology.