1475 Nicholas Jenson
I need a better sample to begin to take this seriously but it has piqued my interest.
Part of why I think it's possible is that he is thought to have trained in Mainz, and knew the type of Johann and Wendelin of Speyer (de Spira), and Sweynheym & Pannartz's Subaico.
( RE: Subaico http://typophile.com/node/43615 )
It would be great to be sure about this. Does anybody have any high-rez images? Or suggestions?