Fig. 2

External views of Stegosaurus sp. YPM 57716 (accession number 1388). a Side view of the dorsal plate previously X-rayed by Farlow et al. (1976: Fig. 1b). The specimen was glued together, and its apical portion restored, with plaster, which appears as a lighter colour in the photograph. A plastic rod is inserted into a large groove in the plate base that leads to an opening into the plate interior. Black arrow near the apex of the plate (as preserved) indicates one of several faint blood grooves in this region of the plate. b Ventral view of the plate base. The large groove leading to the opening into the plate interior in (a) is indicated by the left-most white arrow; the opening itself is adjacent to the arrow. Other white arrows mark two of several more additional openings from the plate base into its interior. Compare with the similarly developed plate base of USNM 4714 (Fig. 1c). c Slightly oblique view of the plate base, with the groove leading to the large opening into the plate interior marked by a black arrow. Another large opening (not readily seen in the view in (b) is at the extreme left edge of the photograph. Scale bars 50 mm (b, c), 100 mm (a)