Pattern in onyomi for middle Chinese -p and -ng finals

Question

I've been thinking recently about patterns between onyomi and their respective Chinese counterparts (as presumably existed in middle Chinese and are now reflected across modern Chinese dialects). Japanese certainly does reflect a lot of the consonant endings that existed in middle Chinese that have been lost in some dialects (particularly Mandarin, which only preserves -r, -n and -ng as consonant finals) (cf. 六 - Mandarin liù, Cantonese luk6, Japanese roku) (cf. 七 - Mandarin qī, Cantonese cat1, Japanese shichi)

I was wondering in particular about the phenomenon regarding the -p final and the -ng final, both of which seem to be widely represented in modern Japanese by the elongation of the vowel sound (cf. 十 - Mandarin shí, Cantonese sap6, Japanese jū) (cf. 零 - Mandarin líng, Cantonese ling4, Japanese rē/rei). Is there any evidence of earlier Japanese having -ng as a valid phoneme, and if not, is there any particular reason why Japanese would have borrowed these elongated-vowel readings as substitutes for the -ng and the -p finals (especially in the case of the latter, which seems like it would be replicable by Japanese phonology)

Answer 1

It's actually due to a couple of things.

For *-p, Japanese actually did originally borrow it as *-pu. Subsequent sound changes have turned Old Japanese *p into /w/ between vowels, and the resulting -(w)u has combined with the vowel before it. (Note that Modern Japanese /p/ is actually a Middle Japanese reintroduction from Chinese; where Old Japanese *p isn't modern /w/ it's /h/.)

十 is an example - MC *dʑip > OJ *dʑipu > MJ *dʑiwu > *dʑiu > *dʑuu > NJ /dʑuu/

For *-ŋ, Japanese originally borrowed it as *-u, because Old Japanese didn't have anything like Modern Japanese's /N/ phoneme (which is new from Middle Japanese). Again, this -u has undergone additional interactions with the vowel before it.

名 is an example - MC *mjᴇŋ > OJ *mijau > MJ *mjɔɔ > NJ /mjoo/

Japanese later borrowed a different set of pronunciations (漢音, as opposed to the above 呉音), where MC *-jᴇŋ finals were borrowed as *-ee instead of *-jau. This is why 名 can also be read /mee/.