DorotheaBrooke wrote: ↑Thu Aug 28, 2025 7:23 pm-/ŋ/ is deleted from onset clusters (except in onset clusters like /dŋ/ where it's in the more sonorous position), which makes sense given how common prohibiting onset velar nasals is.
Onset velar nasals are relatively rare, but I'd think that clusters like the /dŋ/ don't occur as the onset (rather than as a full syllable with /d/ being the onset and /ŋ/ being the nucleus).
However, this rule crosses word boundaries, so words ending in vowels (...) cause the retention of the historic velar nasal since it gets syllabified as a coda.
"this rule crosses word boundaries" seems a bit imprecise. I get what you mean, but formulated like that it sounds like you're talking about a sandhi rule that extends to word clusters.
By analogy, speakers start inserting [ŋ] on words beginning with vowels after words ending in vowels; i.e. /ábdi/ "stone" but [rí ŋábdi] "four stones." Basically intrusive-r, but word initial.
This kinda contradicts what you wrote above. It can't be both retention and intrusive. Not saying the process itself is unlikely, but you need to better describe it imho.
This could potentially go a few different ways depending on the descendants; I was thinking that one descendant could keep the pattern, another inserts [ŋ] before all initial vowels, and a third could insert [ŋ] only on words that are often preceded by vowels, like inanimate nouns (which can't serve as subjects) or verbs (in this SOV language).
"Keeping the pattern" means the "intrusive-ŋ" right? So inter-word vowel collisions are solved by inserting a /ŋ/. "Insert /ŋ/ before all initial vowels" - that would only work if there are relatively little (I can't see a situation where 90% of words start with a /ŋ/), and I'm also not sure whether that would work given it starts off as "intrusive-ŋ". I can't easily see such an intrusive sound being recodified as a phoneme unless it's very uncommon (but based on what you write it's common). "inser /ŋ/ only on words preceeded by vowels" - same objections as the previous, once it's intrusive it's difficult to phonemize it. Otherwise this is similar to what happened in English with words like "adder" (from "nadder") and the famous French "licorne" (unicorn -> un icorn -> l'icorn -> licorn).
So I think you can save the three different patterns in daughter languages by
not having the intrusive-ŋ phase in the parent language, but have some unstable system in the parent language and have the daughter languages develop the systems you described.
JAL