PIE/Latin/Greek Nominatives

[evmdbm]

So this could be another of those "A little bit of knowledge is a dangerous thing" moments...

In Latin there seems to be an -s thing going on with the nominative case. Many of the second declension masculine nouns end in -us in the nominative singular. Some in -er, but mostly -us (servus) There's also an -us thing going on in the 4th declension again with masculine nouns (arcus) and a -s thing in the fifth declension (res). There's even an -s thing in the 3rd declension, although sometimes harder to see. Take for example rex (nom), regem (acc), but if you take the reg- stem and add an -s regs this will devoice naturally to rex.

There's an -os thing going on in Ancient Greek, although my Latin is better than my Greek so i can't go through all the Greek declensions the way I did with Latin.

I wondered if any of this pointed to a marked nominative system existing or having existed at some point in PIE?

[WeepingElf]

So this could be another of those "A little bit of knowledge is a dangerous thing" moments...

[...]

I wondered if any of this pointed to a marked nominative system existing or having existed at some point in PIE?

This has been discussed for a long time and is still being discussed among IEists; no consensus has been reached yet on this question.

[alice]

(deleted)

[Estav]

In Latin there seems to be an -s thing going on with the nominative case. Many of the second declension masculine nouns end in -us in the nominative singular. Some in -er, but mostly -us (servus) There's also an -us thing going on in the 4th declension again with masculine nouns (arcus) and a -s thing in the fifth declension (res). There's even an -s thing in the 3rd declension, although sometimes harder to see. Take for example rex (nom), regem (acc), but if you take the reg- stem and add an -s regs this will devoice naturally to rex.

There's an -os thing going on in Ancient Greek, although my Latin is better than my Greek so i can't go through all the Greek declensions the way I did with Latin.

I wondered if any of this pointed to a marked nominative system existing or having existed at some point in PIE?

It is the case that the PIE nominative singular is marked by the suffix -s for most types of non-neuter nouns (most alternative endings such as Latin -er developed by sound change from a form originally ending in *s); preceding vowels like o/u are etymologically part of the stem not part of the case-marking suffix. (But some nouns have stem changes between cases.) Neuter nouns have a nom/acc/voc singular consisting of the bare stem, except for o-stems which have -m. I don’t know how “marked nominative system” is defined.

[hwhatting]

Just to add, the s-less female nominatoves in (Latin) -a, Greek -e: / -a: etc. are nowadays mostly explained as being originally the same as the neuter plural, i.e. old collective nouns (PIE *-eH2 etc.)
Most scholars nowadays assume that PIE orginally had a system with animate nouns having a Nom. Sg. in *-s and an Acc. Sg. in *-m, and inanimate nouns with a zero ending in both cases; the animate class split into male and female with the integration of the former collective nouns into the animate class. Whether the Nom / Acc ending *-om in the neuter o-stems has anything to do with the accusative or not is being debated.

[alice]

Boring old *s and *m weren't enough for the thematic stems, though; they got *bh and *d in other cases too.

[hwhatting]

Boring old *s and *m weren't enough for the thematic stems, though; they got *bh and *d in other cases too.

Well, if you want to build an 8-case system, it's good to have e a counple more consonants for variety

[Rounin Ryuuji]

I believe it's assumed that the case markers would've originally been cliticised case marking particles of some description?

[hwhatting]

I believe it's assumed that the case markers would've originally been cliticised case marking particles of some description?

Nobody really knows. There are many different opinions about the original genesis of the case marking system, and at least some of the markers may have marked something else than noun case originally.

[Rounin Ryuuji]

Is there any theory for how case endings (and other inflections) might've formed if not from auxiliary words (or from analogous forms developed from forms derived from auxiliary words)?

[hwhatting]

Is there any theory for how case endings (and other inflections) might've formed if not from auxiliary words (or from analogous forms developed from forms derived from auxiliary words)?

Well, if you go back long enough, you'll probably find auxiliary words behind almost every affix; it's just that it's frequently beyond the reach of reconstruction. (Exception: reduplication, which doesn't have to go back to auxiliary words, but which in PIE is used only for stem-formation and the verbal system, not in the case system).
For a contemporary theory how PIE flexion came about, look at stuff by Ronald Pooth (a lot of that is on academia.edu); his theories are by far not the common opinion, but he has an interesting apparoach and also discusses older theories.