A. Nasal in left lateral view. B. Line drawing of nasal in left lateral view. C. Nasal in right lateral view. D. Line drawing of nasal in right lateral view. E. Nasal in dorsal view. F. Line drawing of nasal in dorsal view. G. Nasal in anterior view. H. Line drawing of nasal in anterior view. I. Hypothetical ‘subadult’ Pachyrhinosaurus perotorum skull outline with DMNH 21460 superimposed to show approximate location of specimen in the skull. Abbreviations: bs, basal sulcus; fr, frontal contact; ms, median sulcus; nh, nasal horn/incipient nasal boss; prf, prefrontal contact; ri, ridge laterally bounding rugose area; rug, rugose patch on dorsal surface of nasal; sb, smooth bone. Gray fill indicates broken bone surfaces or cracks. Scale bars equal 5 cm.