The three plosives and the affricate *c /ts/ also possessed a half-long duration ([pˑ], [tˑ], [kˑ] and [tsˑ]), but these appear to have been in complementary (allophonic) distribution with fully long consonants, and therefore are not thought to have been phonemic.
However, it was still productive after certain sound changes specific to Finnic, such as the apocope of final *-i, so it was probably present as a phonetic "post-processing" rule (a surface filter) over a long period of time.
It was not present in ancestral Proto-Uralic, and many instances of ö found in modern Finnic languages have only developed after Proto-Finnic, due to various sound changes.
For example, Finnish has öy from *eü: löytä- 'to find', köysi 'rope' < Proto-Finnic *leütä-, *keüci, while Estonian has unrounded the diphthong instead, giving leida- and köis.
Some modern Finnic languages have redeveloped long vowels and additional diphthongs in non-initial syllables as a result of the loss of certain consonants (generally d, g and h).
For example, partitive *-ta would appear as *-da when added to a two-syllable word ending in a vowel (e.g. *kala, *kalada "fish"), but as *-ta after a third syllable or a consonant (*veci, *vettä "water").
The following cases were present:[17][22] The genitive plural was formed in two different ways: Both types are still found in Finnish, although unevenly distributed.
Its consonantal nature is apparent in an older, now-obsolete essive case form of the superlative in Finnish, which ended in -inna (< *-im-na < *-ime-na with syncope).
The original vowels in the plural possessor endings are not settled: evidence exists for both *A (that is, *a ~ *ä) and *e. Laakso (2001) recognizes variation only for 1PP and 2PP (giving *A for 3PP).
Possessive suffixes were ordered after case endings, and typically attach to the oblique vowel stem: e.g. *sormi : *sorme-mi 'my finger'.
The number-of-possessed contrast is by the 20th century lost everywhere except in the Southeastern Tavastian dialect of Finnish, around the municipalities of Iitti and Orimattila, and even there only in the nominative in the first and second person singular.
Standard Finnish adopts 1PP -mme (derived from the singular possessed series, with analogical mm based on the verbal inflection), but 1PS -ni, 2PP -nne (derived from the plural possessed series, with regular *nd > nn); and adopts 3PS -nsA in the nominative, illative and instructive (nominative käte-nsä 'her/his hand'), but -Vn (< *-hen) in all other cases (e.g. inessive kädessä-än 'in her/his hand').
New plurality-of-possessed marking has emerged in the Soikkola dialect of Ingrian, suffixing the usual nominative plural marker -t, e.g. venehe-mme-t 'our boats'.
[24] Old Finnish shows two archaic features in the possessive paradigm: the number-of-possessed contrast (singular poikaise-mi 'my son', versus plural luu-ni 'my bones'), and the 2nd person singular ending may attach also to the consonant stem of a nominal, with a non-assibilated ending -ti (the expected regular development before old *s, *t and *h < *š): e.g. rakkaus : rakkaut-ti 'your love', tutkain : tutkain-ti 'your prod' (modern Finnish rakkaute-si, tutkaime-si).
The imperative had its own set of endings:[17] There is also some evidence of a distinct optative mood, which is preserved in Finnish as -os (second-person singular).
These changes happened very late in the Proto-Finnic period, but as South Estonian developed somewhat differently, it shows that dialectal diversification was beginning to occur around this time.
The non-geminated *c becomes *s generally: Proto-Finnic *veci "water", *cika "pig", *-inen : *-ice- (adjective suffix) > Finnish vesi, sika, -(i)nen : -(i)se-.
The merging of *c and *s often makes it impossible to distinguish the two sounds using Finnic evidence alone, if internal reconstruction is not viable (e. g., from t ~ s alternations from assibilation).
In early Finnish, both grades were fronted to interdental θθ : θ, which in most dialects later changed into a variety of other dialect-specific sounds.
South Estonian and Votic show this development in all syllables, so that e and õ become a front and back vowel harmony pair.
[32] The development of *o to õ is the most general in Votic (if recent loanwords from Ingrian, Finnish and Russian are discounted)[33] and in the Kodavere dialect of Estonian.
Colloquial Finnish loses word-final i under more limited conditions, in particular after s (e.g. kaks "two", viis "5"; inflectional endings such as aamuks "for/to the morning" (translative), talos "your house" (2nd person singular possessive), tulis "would come" (3rd person singular conditional)) as well as word-final a/ä from several inflectional endings (e.g. inessive -s(s), elative -st, adessive -l(l), ablative -lt).
Many languages in the Southern Finnic group, as well as again Veps and Southwestern Finnish, show loss of unstressed vowels in medial syllables.
The most widespread source is regressive palatalization due to a lost word-final or word-medial *-i (a form of cheshirization), and consonant clusters with *j as a second member.
Estonian, Votic and Finnish do not have general palatalization, and š occurs almost solely in loanwords, most commonly of Russian or German origin.
The voiced obstruents *b/β, *d/δ and *g/γ that occurred as the weak grades of single plosives were often lost or modified in various ways.
The simplest outcomes are in the marginal languages Livonian, Ludic and Veps, where all three are reflected as plain voiced stops b, d and g respectively regardless of environment.
[37] The long mid vowels *oo, *öö and *ee become opening diphthongs /uo̯/, /yø̯/, /ie̯/ in Finnish, Karelian, and several marginal dialects of Northern Estonian.
In South Estonian, raising only occurs in overlong syllables, and results in long close vowels uu, üü and ii.
Syllable-final *l is vocalized in Veps at a late date, creating u-final diphthongs in the northern and central dialects, long vowels in the southern.