posited nasal consonants in Proto-Siouan. Nasal consonants only arise in daughter languages when followed by a nasal vowel. In addition, there is a set of sounds that represent obstruentized versions of their corresponding sonorants. These sounds have different reflexes in daughter languages, with *w appearing as [w] or [m] in most daughter languages, while *W has a reflex of [w], [b], [mb], or [p]. The actual phonetic value of these obstruents is an issue of some debate, with some arguing that they arise through geminated *w+*w or *r+*r sequences or a laryngeal plus *w or *r. Vowels Previous work on Proto-Siouan only posited single vowel length. However, phonemic vowel length exists in several Siouan languages such as Hidatsa, Ho-Chunk, and Tutelo. Rankin et al. (2015) analyze numerous instances of long vowels as present due to common inheritance rather than common innovation. The five oral vowels and three nasal vowels posited by earlier scholars is expanded to include a distinction between short and long vowels. The proposed Proto-Siouan vowel system appears below: Oral vowels Nasal vowels External relations The Yuchi isolate may be the closest relative of Sioux–Catawban, based on both sound changes and morphological comparison. In the 19th century, Robert Latham suggested that the Siouan languages are related to the Caddoan and Iroquoian languages. In 1931, Louis Allen presented the first list of systematic correspondences between a set of 25 lexical items in Siouan and Iroquoian. In the 1960s and 1970s, Wallace Chafe further explored the link between Siouan and Caddoan languages. In the 1990s, Marianne Mithun compared the morphology and syntax of all the three families. At present, this Macro-Siouan hypothesis is not considered proven, and the similarities between the three families may instead be due to their protolanguages having been part of a sprachbund. References Bibliography Parks, Douglas R.; & Rankin, Robert L. (2001). "The Siouan languages." In R. J. DeMallie (Ed.), Handbook of North American Indians: Plains (Vol. 13, Part 1, pp. 94–114). W. C. Sturtevant (Gen. Ed.). Washington, D.C.: Smithsonian Institution. . Further reading External links Comparative Siouan Dictionary Siouan languages mailing list archive Language families Indigenous languages of the North American Plains Sioux culture Indigenous languages of Maryland