The linguists at Chásur reconstruct Proto-Taol something like this:p t kʲ k ˀp ˀt ˀkʲ ˀk pʰ tʰ kʲʰ kʰ f? s ʃ h n l r ʁ i e a ɑ o u ī ē ā ɑ̄ ō ū î? ê â ɑ̂? ô û?
The existence of *f is uncertain; it is largely reconstructed to explain Maotic words which have /h/ (instead of Ø), however, it has been noted that most such instances precede /a/, e.g. *fālu > hálu "female human".
kʲ ʃ will be spelled *c *š.
The second vowel series is the long counterpart of the first. The third vowel series, marked with a circumflex, is infrequent; its properties are uncertain, but it was preserved into the earliest stages of all Taol languages (including Eastern Taol, which lost length) long enough to be invariably marked in the standard orthographies. In Maotic both the second and third series collapsed into the first; in Dálx the second and third series are both pronounced as long; additionally, the circumflex marks vowels compensatorily lengthened by the loss of a consonant (e.g. *lek-ši > lês. In Eastern Taol the third series is pronounced long (usually analyzed as doubling of the vowel, e.g. âcasi /a.a.tʃa.si/, etc.) The origin of the third series in Proto-* shows several apparent contractions in *VyV, among scattered other sources.
A rough sketch of changes from Proto-Taol to the earliest literary period looks like so:short *ɑ merges with /o/, long *ɑ̄ breaks to /ao/long *ū breaks to /ue/preglottalized consonants become voiced and lose preglottalization
* loss of final *iloss of *š universally
* loss of *h universally? debuccalization of *f > hshift of /n/ to /m/ when initial or preceding nearby /n/+a very strange change to be sure, but the distribution bears it out
loss of gemination*kʲ > [ts] allophonically before front vowels /e i/; gʲ > /dz/ universally
Later final /e/, /a/ were lost (compare literary fíre with modern fír "tree"), and more importantly the entire length contrast.