Table 1.

Summary of the most significant osteological trends throughout the cranial ontogeny of T. radix (see text for details). LARST, lateral aperture of the recessus scalae tympani.

bone	embryo	juvenile	adult
premaxilla	— minimal contact with rest of snout	— as in embryo	— stronger integration with rest of snout
nasal	— dorsal laminae present only as a very weakly ossified surface	— increased ossification of dorsal laminae	— completely ossified
frontal	— no contact with parietals — posterior third unsutured	— minor contact with parietal, though fontanelle persists	— complete contact with parietal — frontals completely sutured
parietal	— central parietal roof unossified — parietal—supraoccipital fontanelle present	— parietal roof ossified — closure of parietal—supraoccipital fontanelle	— prominent muscle attachment crests
pterygoid	— posterior terminus below occipital condyle	— posterior terminus slightly beyond occipital condyle	— major posterior elongation of tooth row and quadrate process
otoccipital	— jugular foramen small, internally undivided — crista tuberalis unfused ventrally to crista interfenestralis, LARST opens laterally	— jugular foramen more defined, still undivided — crista tuberalis expanded, but still unfused to crista interfenestralis	— jugular foramen large, subdivided, with well-defined jugular recess — crista tuberalis fused to crista interfenestralis
quadrate	— anterior to occipital condyle — only slightly off-vertical	— dorsoventrally elongated — slight posterior shift	— further elongation — posterior to occiput — ventral terminus rotated strongly posteriorly
supratemporal	— posterior terminus downcurved and anterior to occiput	— no downward curvature — slight posterior elongation	— posterior terminus well posterior to occiput
compound bone	— terminates slightly posteroventral to occipital condyle — mandibular condyle anterior to occipital condyle	— slight posterior elongation; — mandibular condyle closer to level of occipital condyle	— strong posterior elongation and posterodorsal deflection; — mandibular condyle well posterior to occiput
dentary	— teeth short, stout and minimally recurved	— teeth longer and narrower than in embryo	— teeth long, narrow and strongly recurved