The Krulanguages belong to the Niger-Congo language family and are spoken in the area ranging from the south-east of Liberia to the east of Côte d'Ivoire. The name Kru is of unknown origin and is according to Westermann (1952) 'used by Europeans to denote a number of tribes speaking related dialects, and the dialects as a whole'.
For instance, the fact that all languages have oral vowel phonemes and only some languages have nasal vowel phonemes is due to the fact that nasal vowels develop out of oral vowels in the context of a nasal consonant, which subsequently is lost.
Greenbergs brilliant discovery was that in unrelated families and languages, parts or all of this path of change are attested, and furthermore that the progression along the path is unidirectional.
More languages preclude /h/ from codas than allow it (see [iv]), but a significant minority not only allows /h/ there, but seems to favor it in the sense that it is one of a small set of allowed coda consonants, as shown in (ii).