“…Once ɯ was a bona fide member of the Resígaro phonological vowel inventory, it could act as a ‘receiving phoneme’ in the primary split depicted in figure 1. As every primary split originates in contextual allophonic variation (Marchand 1956: 247; Hoenigswald 1960: 91–93), the word-final merger of *a , inherited by Resígaro, and ɯ , which entered the language via contact with Bora, consisted in word-final allophones of *a becoming associated with the phoneme ɯ . Given the phonetic properties of a and ɯ , it is plausible that this partial merger was facilitated by the occurrence of higher or more centralized allophones of *a in word-final position, represented in (4) as *[ə] 15…”