Plains Algonquian languages (Blackfoot, Cheyenne, and Arapahoan), though they don't form a genetic group, are distinguished from other Algonquian languages by a lot of really unusual changes, some specific to each language and others diffused among several of them (the most bizarre changes being in Cheyenne and Arapahoan). The result is that you really have to know the correspondences to recognize just about any cognate in any of the Plains languages with equivalents in other members of the family or in Proto-Algonquian. Some of the changes are chronicled in various places in the Correspondence Library, but I'll highlight the most interesting/unusual/bizarre ones here.
Cheyenne and the Arapahoan languages share several. One is the merger of the semi-vowels *j and *w into *j (unconditionally in Arapahoan, postconsonantally in Cheyenne; this parallels the Hebrew change sirdanilot mentioned), which in most cases then further changed to n (perhaps by way of something like *ɲ) -- so Cheyenne and the Arapahoan languages often reflect Proto-Algonquian [PA] *j and *w as n! In fact, in Cheyenne, this also affected the automatic palatal offglide which developed between a *k (which was later lost) and a following front vowel, leading to the correspondence PA *k : Cheyenne n. In Arapahoan, word-initial *s became n as well. Another shared unusual change is the loss of *k (irregularly in Cheyenne), and in Arapahoan, the resulting shift of the labial stop *p to a velar *k (which later split into /k/ and /ʧ/; for more on labial-velar interchange, see below).
In Blackfoot, *k was not lost, but initial *t did shift to k (as in Austronesian!), e.g. koʔkó- "be night" (< PA *tepeskwatwi > something like *topskwawi- > etc). Blackfoot also changed *j to s and postconsonantal *j (and sometimes *w) to isi or isa in a number of cases, e.g. moʔksísi "armpit" (< PA *meθenkwi > something like *moθnkwi > > *moθnkji > > *moθnksisi > etc.) and mó:sa "anus" (< PA *mje:ji "piece of dung" > something like *me:ji > > *me:si > etc.). Cheyenne also has the change *j → t in some environments (as in sɪ́joto̥ "ghosts" < PA *ʧi:pajaki [the /j/ in the modern Cheyenne form is a later addition to break a vowel hiatus, and does not reflect the original */j/, which is continued by the modern /t/]). Gros Ventre has several unusual changes of its own, including the shift of word-final *θ and *k to ʦ and *m to bʲ.
To summarize, we have changes like:
*j → t /$__
*w → *j /C__
*k → Ø
*j → n
*t → k /#__
*j → s /__V#
*w → j /k__i
*ja, *ji → sa, si /C__#
*w → *j
*j → n /$__
*k → Ø
*p → *k
*s → n /#__
*k, *θ, *m → ts, ts, bʲ /__#
The result, as I noted, is some extremely unusual and opaque correspondences/etymologies. For example, Cheyenne nɪtsɪ̥ "eagle" (< PA *keriwa > something like *kjeri > > *jiti > > *niti > etc.; cf. Ojibwe giniw) and -onɪ́sɪ- "try to" (< PA *kakwe:ʧi- > something like *kakje:ʧi- > > *aje:ʧi > *ane:ʧi > etc.; cf. Oj. gagwe:(ʤi)-); Arapaho ní:ʧí: "river" (< PA *si:pi:wi > *si:pi: > *si:ki: > *ni:ki: > etc.; cf. Oj. zi:bi), nóúbe: "fly (n.)" (< PA *sakime:wa "mosquito" > *sakime:j > *saime:n > *naime:n > etc.; cf. Ojibwe zagime:), and hené:ʧe:nóʔ "buffalo bulls" (< PA *aja:pe:waki "male ungulates" > > *aja:pe:jak > *ana:pe:nak > *ana:ke:nak > etc.; cf. Oj. aja:be:g); and Gros Ventre ʔóts "arrow" (< PA *aθwi > > *oθ > etc.; cf. Oj. anwi "bullet"), ʔé:je: "sparrow hawk" (< PA *ke:hke:kwa "hawk sp." > > *ke:ke:k > *e:e: > etc.; cf. Oj. ge:k:e:k), and bê:síbʲ "plum" (< PA *meʔʃi:mini "large fruit" > *meʔʃi:min > > *meʔʃi:m > etc.; cf. Oj. miʃ:i:min "apple").
The labial/velar interchange that happened in Arapahoan also has parallels in Austronesian, though in the other direction and with some complications: Sa'ban changed PMP *ɡ to p, ʤ, or zero initially, p finally, and ʤ intervocalically (e.g., ajəŋ "spinning top" < PMP *ɡaiŋ; ʤɪntoʔon "star" < PMP *ɡituqən; peləp "skittish" < PMP *ɡiləɡ; bəlʔup "wasp" < PMP *bəluquɡ; and aʤiəp "rice sieve" < PMP *aɡaɡ). And it's happened other places too (and of course acoustically labials and velars are both fairly similar, and are generally described as sharing the feature [+grave]), so it's not totally outrageous, but it is still uncommon.
Last edited by Whimemsz on Mon Jul 02, 2012 3:06 pm, edited 1 time in total.