Board Thread:Warhammer 40k General Discussion/@comment-86.7.138.66-20130615215334/@comment-6078851-20130617025154

i think the shadow in the warp is simply a by-product of the scale of the tyranid conciousness, and while it has an affect in the warp tyranids don't actually use the warp anything like how everyone else does, their psychic abilities are derived from their own species and they use a little 'warp energy' for a boost if they want to, but as i understand it they can use devastating psychic abilities without even touching the warp.

as for the old ones creating tyranids - nope. the tyranid race has traversed intergalactic space multiple times, at sub-light speed, and so the time-frame this implies means the tyranids pre-date the old ones, by a long long way.

maybe the old ones were a radical splinter fleet from the ancient tyranids :P