Sorry,in this case it's strictly true - Are you familier with the aforesaid thrust bearing. I may have made the mistake of calling it a taper bearing.
It's COMPLETELY flat, circular with rollers in a cage. And runs sandwiched between two flat metal surfaces.
flat disc bearings do have the problem of different rolling radii, thats very true, whereas taper rollers overcome that problem by being...er...tapered.

Come on blokes -more effort 