User blog comment:Antares2/Mass Effect 3: Resurrection Pack (Idea)/@comment-5107124-20120602004620

I think the Oravores idea is not possible because of their conflicts with the Protheans. Seeing as how they were threatening their work with the Asari, it makes sense that the Protheans would have had them exterminated. Regarding the Zha'til, this bit from the wiki says it all.

"... the Protheans sent the star of the zha's home system into supernova, destroying the zha'til entirely."