Fig. 7 in A new Arctic hadrosaurid from the Prince Creek Formation (lower Maastrichtian) of northern Alaska

Fig. 7. Postorbital comparison of a size class 3 Ugrunaaluk kuukpikensis gen. et sp. nov. (A, UAMES 33308) from the early Maastrichtian Prince Creek Formation, Alaska, right postorbital in medial (A1) and anterior (A2) views; size class 2 Edmontosaurus annectens Marsh, 1982 (B, ROM 53513, reversed) from the late Maastrichtian Lance Formation, Wyoming, USA, left postorbital in medial (B1) and anterior (B2) views; and adult Kundurosaurus nagornyi C, AENM 2/921-6) from the Maastrichtian Udurchukan Formation, Kundur, Russia, left postorbital in medial view (from Godefroit et al. 2012: fig. 6). Note that size class 3 of U. kuukpikensis does not possess a deep posterior orbital pocket seen in the size class 2 specimens of E. annectens, although the articular surface with the frontal is nearly identical. D. Left postorbital of E. annectens (CMN 8509) from the late Maastrichtian Lance Formation, Saskatchewan, Canada, showing how the jugal process width is defined. E. Postorbital regression analyses. Biplots of the width of the jugal process measured at one-quarter distance from its dorsal end versus dentary length. U. kuukpikensis has a narrower jugal process than Edmontosaurus regalis. For E. regalis and U. kuukpikensis the numbers in the parentheses are those calculated when the minimum dentary length, not average, is adopted as the body size proxy. When the regression lines have statistically indistinguishable slope values but show statistically significant differences in elevation, P values are marked with an asterisk. The 95% confidence interval of U. kuukpikensis dentary length is also shown by the bi-directional arrow.