Developed Phonemes In certain clusters of consonants there tend to develop other consonants. There are sometimes called 'transition' consonants, for they arise from articulatory transitions from one to another position or type of combination. The following are some of the more common types: 'mr' > 'mbr', 'mk' > 'mpk', 'ŋr' > 'ŋgr', 'nr' > 'ndr', 'ns' > 'nts', 'ŋt' > 'nkt', 'sr' > 'str', 'zr' > 'zdr', 'lr' > 'ldr'. Developed consonants are, however, quite rare. In sequences of consonants transition vowels sometimes develop. These tend to be short and to have mid and central quality. Such vowels are comparatively rare.
- Nida (1949), a pag.307