This is a draft for some work that 'ties' together one detail in Dairwueh, Bryatesle and Sargaĺk. Details may still change.
Proto-Bryatosargaĺk had a subject postposition, probably something like dant. It's most clear descendant is the pegative marker -ta in Sargaĺk, the two -at-suffixes in the Dairwueh case system are probably descendants as well but less obvious examples. Some masculine and feminine nouns in Bryatesle have also incorporated it into their lexical forms.
However, subject adpositions seem to have been a sufficiently important trait in the syntax of PBS that new ones took its place in branches that lost 'dant'.
From the evidence, we can gather that it is unlikely the subject postposition was mandatory in every subject NP - rather, subjects with certain particular semantic or syntactic properties called for it. In all descendant languages, the subject postposition leaves some traces, but the traces are somewhat spread out.
1. Sargalk
In Sargalk, the postposition became the pegative case. This case marks the subject of a ditransitive verb, but also appears in some other contexts:
- with some particular verbs
- before some postpositions
- to mark intensity of actions
- for subjects of generic statements about a class (generally in singular)
- agent-like, or agent-associated comitatives
- an optional marker for transitive subjects that had been displaced from their expected place in the clause
- entire subclauses and gerunds standing as subjects of a verb
- after a demonstrative that is a subject, when its referent is the previous sentence
- contrasted subjects
- whenever an explicit subject is present with an imperative
- the agent of passives
2. Dairwueh
In Dairwueh, dant has no direct descendant outside of morphology, but the preposition 'bur' has taken up a similar role. It appears in the following contexts:
- as a marker of resumptiveness in subclauses
- emphasized 'continued same subject'-pronouns
- sometimes to mark definite intransitive subjects
- with loan words that cannot be inflected for case, and with NPs that have no case-bearing marker (e.g. a subclause or similar)
- subjects in subclauses, and as an introducer of subject-oriented subclauses
- in comparisons of subject to subject, the subordinate subject has this marker
- in clauses with a vocative, to distinguish which NP is subject and which is vocative.
- in some dialects, atypical subjects such as mass nouns take it
- enables subjects to take a preprepositional, which usually used to convey in what capacity someone does something.
3. Bryatelse
Modern Standard Bryatesle lost 'dant', but gained a postposition 'uid', in some dialects 'uib'. There are also dialectal traces of 'dant'.
The 'uid' postposition:
- relative clauses that relativize the subject mandatorily have this marker on the subject - even if it strictly speaking is outside of the subclause.
- comparisons of subjects
- subjects in subclauses mandatorily take 'uid'.
- generic statements about a class of things (generally singular)
- a handful of verbs require 'uid' for the subject.
- similar vocative distinction as in Dairwueh
- a few dialects have adapted 'uid' to be a copula.
Traces of 'dant':
- in northeastern dialects, the definite form is a result of *dant → end.
- in southeastern dialects, *dant → ''tẽum" functions as an existential verb.
- In some dialects, *dant → -tɨnt is the secondary subject marker. The majority of dialects have -nisr, which probably derives from a different postposition that also operated as some kind of subject-postposition-like thing.
