Palatalization of Proto-Altaic' /k/ and some successiv reorganization of the vowel system introduced a new palatoalveolar consonant series, separate from retroflex. Dorsal nasals developed from glides in vicinity of other nasals; *ŋ seems to have however been at least in late PEA' purely velar, not palatalized. Smaller changes include f → ∅ and b → β.
The stops were very likely allophonically voiced when prenasal, as they developed to voiced stops almost always in daughterlangs in that position.
|Labial|| Dental /
Vowels come in four tense-lax pairs:
PA' *i, *ɪ, *u, *ʊ are continued regularly, save for some tensing/laxing effects and labiality assimilations. *ej, *o, *ow (but *e generally not) raise to *i, *u, *u while *ɛ, *ɔ merge to *ɜ, which upon tensing defaults to *e. *a is split to *ɑ (upon secondary tensing) and *æ (default); *aj, *aw both yield *ɑ.
"Noun class" suffixes include at least -t, -q, -l; whether these were actual codas in Proto-Altaic' or were a result of apocope remains to be seen (decided). The actual semantic meaning may have been diminutiv for -t and collectiv for -l.
Splits to Proto-East-A Altaic', Proto-East-B Altaic' and Proto-East-C Altaic' ca. -2ka.