Figure 13. A in Ontogeny and variation of the pachycephalosaurine dinosaur Sphaerotholus buchholtzae, and its systematics within the genus

Figure 13. A, stratigraphic distribution of the three Sphaerotholus species throughout the Late Cretaceous. 1, S. buchholtzae; 2, S. edmontonensis, 3, S. goodwini. Stratigraphic section modified from Williamson & Carr (2002). B, distribution of S. buchholtzae specimens throughout the Hell Creek Formation. Modified from Williamson & Carr (2002). Specimens not to scale.