Before the Schism of 1054, the bishop's crozier most often had a Tau-shaped head. Here is a picture of a typical Western Orthodox crozier top:
(above: Typical old Roman rite crozier, from Cologne, Germany, circa 1000 A.D.)
The other style, which is known to have been used prior to the Schism, is the shepherd's crook style.
The first predominated before the Schism, the second after the Schism.
Hat tip to Christopher McAvoy of Pennsylvania.
P.S. Old style Western Rite bishop's vestments:
