Cranial densities in <i>Giraffa</i> (TMM M 6815, UCMZ 1976.33), the peccary <i>Tayassu</i> (UCMZ 1975.279), and pachycephalosaur <i>Prenocephale</i> (GI SPS, field number PJC2004.8).

<p>CT sections through crania of comparative taxa, with slices mapped onto lateral renders of crania. A. <i>Giraffa camelopardalis</i> male (TMM M6815), transverse section through the region of a median ossicone. B. Oblique transverse section of <i>Giraffa camelopardalis</i> (UCMZ 1976.33) through the posterior ossicones. C. Enlargement of B focusing on the ossicones. The layering of densities in the giraffe ossicones resembles that in the dome of <i>Stegoceras validum</i> (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0021422#pone-0021422-g006" target="_blank">Figure 6</a>). D. Transverse section through the cranium of <i>Tayassu tajacu</i>, showing a non-cancellous skull roof over cranial sinuses. D. Section through the cranium of the pachycephalosaur <i>Prenocephale prenes</i> (GI SPS). Despite mineral inclusions (localized red and yellow areas) and CT artifacts, the scan shows dense superficial and cancellous deep regions within the dome. Abbreviations: ec = endocranial cavity, fs = frontal sinus, lo = lateral ossicone; mo = median ossicone; ps = parietal sinus.