"The Proto-Italic language is the ancestor of the Italic languages, including notably Latin."
That is supposed to mean: The Italic languages include Latin.
I suppose that sentence is wrong, because the relative phrase is a participle phrase that could be replaced with a which phrase and I learned not to use a comma there. In contrast, I'd always add it before the non-restrictive relative clause (I mean the which clause).
Am I right? I tried reading the wiki article on relative clauses, but that was too much for me.