Primitive short [ŏ] did not survive in any Danian dialects, since short [ŏ] became [a] in Primitive Danian (PE19/26). However, short [ŏ] could arise later from vowel mutation, since short [u] became [o] preceding final [a].

Primitive long [ō] survived in both Danian dialects, and could developed by other means as well: the diphthong [au] became [ō] in Ossiriandic, both original and as a development from primitive diphthong [oi] (PE19/25), while [ǭ] became [ō] in East Danian, both original and a development from primitive long [ā] (PE19/25).