Appendix 2. Comparison of light photograph of the anterior dorsal portion of Pachyrhachis problematicus (HUJ-PAL 3659) and CT reconstruction of densities represented as a surface model. Note artifacts introduced by lighting conditions and differences in apparent surface fractures, morphology, and sutures when comparing the light photograph and the density derived model. For example, crushing into the Meckel’s groove previously interpreted as a second mental foramen, morphology of purported medial process of postorbital, the relationship of the maxillae to the prefrontals, and the posterior margin of the parietal table.