View source for Proto-Rathmosian/Later Developments

===Common Changes===
* unstressed ''eC'' > ''iC'' and ''eyC'' > ''iyC''
* word-final, short ''a, e'' lost in words of 3 or more syllables: ''negara'' > ''negar''
* loss of word-final nasals ''-n'', ''-m'' with nasalisation or preceding vowel, creating new ''ą, ę, į, ų, ɚ'' and ''ąą, ęę, įį, ųų''
* loss of word-final ''-t'' 
* raising of ''e'' > ''i'', ''ew > iw'' and ''ey'' > ''iy'' before ''i'' or ''y'' in the next syllable
* loss of ''y'' between vowels and contraction of remaining vowels
* loss of word-final short, non-nasal vowels in words of 3 or more syllables: ''negani'' > ''negan''
* raising of ''a(a)'' > ''ä(ä)'', ''u(u)'' > ''ü(ü)'' before ''i, y'' in the following syllable
* lowering of ''u(u)'' > new vowel ''o(o)'' before ''a(a), ä(ä), ą(ą)'' in the next syllable: ''kukad'' "he eats" > ''kokad''.
* unstressed diphthongs become long vowels: ''aw > oo, ay > ee, ew > oo, ey > ee''
* final-syllable long vowels shortened

{| class="wikitable" style="text-align: center;"
|-
! Pr-Rs!! Stressed !! Unstressed !! Word-Final !! i-mutated || -n/-m 
|-
! a 
| colspan="2;" | a || a / - || ä || ą 
|-
! e
| e || i || e / - || i || į 
|- 
! i
| colspan="2;"  | i || i / - || || į 
|-
! rowspan="2;" | u
| colspan="2;" | u || u / - || ü || ų 
|-
| colspan="2;" | o (bef. ''a'') || || ||
|-
! ə
| colspan="2;" | ə ||  || || ę 
|-
! aa 
| colspan="2;" | aa || a || ää || ą 
|-
! ee
| colspan="2;" | ee || e || ii || ę
|- 
! ii
| colspan="2;" | ii || i || || į 
|-
! rowspan="2;" | uu
| colspan="2;" | uu || u || üü || ų 
|-
| colspan="2;" | oo || o || ||
|-
! aw
| aw || oo || o || äw || -ǫ
|-
! ew
| ew || öö || e || iw || -ę
|-
! iw
| iw || üü || i || iw || -į
|-
! uw
| uw || uu || u || üw || -ų
|-
! ay
| ay || ää || e || äy || -ę
|-
! ey
| ey || ee || e || iy || -ę
|-
! iy
| iy || ii || i || || -į
|-
! uy
| uy || üü || i || uy || -ų
|-
|}

The changes described above resulted in the following vowel inventory for the late common period:

{| class="wikitable" style="text-align: center;"
|-
! rowspan="2;" |  !! colspan="2;" | Front !! Central !! Back
|-
! -Round !! +Round !! -Round !! +Round
|-
! Close 
|| ''i'' /i/ <br>''ii'' /iː/ <br> ''į'' /ĩ/ || ''ü'' /y/ <br> ''üü'' /yː/ ||  || ''u'' /u/ <br> ''uu'' /uː/ <br> ''ų'' /ũ/
|-
! Mid
|| ''e'' /e/ <br> ''ee'' /eː/ <br> ''ę'' /ẽ/ || ''ö'' /ø/ <br> ''öö'' /øː/ || ''ə'' /ə/ || ''o'' /o/ <br> ''oo'' /oː/ <br> ''ǫ'' /õ/
|-
! Open
| ''ä'' /æ/ <br> ''ää'' /æː/ || || ''a'' /a/ <br> ''aa'' /aː/ <br> ''ą'' /ã/ ||
|}

===Rathmos Changes===
* ''ə(ə)'' > ''e(e)'', ''ɚ > a''
* nasals followed by fricatives are lost, leading to compensatory lengthening and nasalisation of preceding vowel: ''negans'' > ''negąąs''
* ''Cy'' > ''CC'', except ''ry''
* ''g'' > /ɣ/ in most positions, except ''ng, gg''
* ''p, t, k'' > ''f, þ, h'' and ''b, d > v, ð'' before ''n, m, l, r''
* ''a(a)'' and ''ay'' raised to ''ä(ä), äy'' except before ''-n, -m'' or before a back vowel (''a(a), o(o), u(u)'') in the next syllable
** unstressed ''äC'' > ''eC''
* word-final ''-a'' lost
* nasal vowels merge with non-nasal counterparts
* stressed ''ä, e, i'' > ''äw, ew, iw'' before ''-w, -lC, rC''
* changes to diphthongs: ''ay > ae, aw > ao, äy > äe, äw > äo, ey > ee, ew > eo, uy
* ''k, g, sk'' palatalised to ''ch'' /t͡ʃ/, ''ȝ'' /ʝ/, ''sh'' /ʃ/ (a) before a front vowel (''ä, e, i, ü'') or ''y'', or (b) after ''e, i'' except when followed by a back vowel: ''negara > neger > neȝer'' but ''neganta > negan''
* i-mutation: ''a(a) > ä(ä), e(e) > i(i), o(o) > ö(ö), u(u) > ü(ü)'' before ''i, y'' in next syllable
* word-final ''-i, -u'' lost, except after light monosyllable
* unstressed vowel reduction:
** medial syllable: ''a, ä, e'' lost, ''i, u'' lost after heavy syllable, > ''e'' after light syllable, ''oo'' > ''o'', other long vowels > short
** final syllable: ''ä, i'' > ''e'', ''uC'' > ''oC'', ''oo > u'', other long vowels > short

===Carrick Changes===
* ''ə(ə), ɚ > a''
* nasal vowels merge with non-nasal counterparts
* i-mutation: ''a(a) > ä(ä), o(o) > ö(ö), u(u) > ü(ü)'' before ''i, y'' in next syllable
* stressed ''e(e)'' > ''ja(a)'', except after ''l, w''
* u-mutation: ''a(a) > o(o), ja(a) > jo(o), ä(ä) > œ(œ), e(e) > ö(ö), i(i) > ü(ü)
* ''y'' lost before front vowels and ''w'' before back vowels, except ''a''
* devoicing of word-final consonants
* ''mp, nk, nt > pp, kk, tt''

===Summary of Vowel Changes===
{| class="wikitable"
|-
! Pr-Rs !! Header text !! Header text
|-
| a || Example || Example
|-
| e || Example || Example
|-
| i || Example || Example
|-
| u || Example || Example
|-
| ə || Example || Example
|-
| aa || Example || Example
|-
| ee || Example || Example
|-
| ii || Example || Example
|-
| uu || Example || Example
|-
|}