text-fig. 11. heropod frontals in ventral view, illustrating character states for characters 37 and 64. a, stereophotographs of articulated frontals of Allosaurus fragilis (UMNH VP 5470); anterior is to the left, b, same as a; outline drawing, c, stereophotographs of articulated posterior skull roof (frontals, parietals, laterosphenoids) of Troödon formosus (AMNH 6174); anterior is to the top. D, same as c; outline drawing. Abbreviations: ce, facet for the cerebral hemispheres on the frontals; f, frontal; 1, facets for the lacrimals; Is, laterosphenoid; lsf, facets for the laterosphenoids; o, orbital facet; ob, facets for the olfactory bulbs on the frontals; pa, parietal; prf, contact with the prefrontal. Scale bars represent 10 mm. in The interrelationships and evolution of basal theropod dinosaurs