Figure 2.

(a) Morphological variability of fossil parietal bones from the smallest (ii) to the largest (iv) and an earlier ontogenetic stage observed by Etheridge [20] (i) (dorsal view). (b) Morphological variability of fossil frontal bones from the smallest (i) to the largest (iv) (dorsal view). (c) Morphological variability of fossil left quadrate bones from the smallest (i) to the largest (iv) (posterior view). a.c., adductor crest; c., conch; d.o., dermal ornamentation; m.d., medial depression, o.c., orbital constriction; p.l., pterygoid lamina; t.c., tympanic crest; s.n., squamosal notch; s.s., squamosal articular surface. (Scale bar, 5 mm.) (Online version in colour.)