Month and leap year display mechanism for timepieces

A month and leap year display mechanism for a timepiece, wherein said mechanism comprises a leap year display integrated in a month display, said mechanism comprising a movement or being arranged to cooperate with a movement, the movement is arranged to drive, via a control mechanism comprised in said mechanism, a month display wheel set rotating about an axis of rotation and arranged underneath a cover plate or underneath a dial, and wherein a month window contained within an angular sector of 90° about said axis of rotation is arranged to allow a user to see a quarter of said month display wheel set, the other three-quarters of said month display wheel set being concealed from the user, and wherein said control mechanism is arranged to make said month display wheel set complete one revolution in four years, and wherein said month display wheel set bears, over an angular sector of 90°, at least one characteristic leap year marking, and either carries indices, each arranged to indicate one month on a static month scale of said dial, or equidistant month markings, wherein one of the month markings is pointed to by a fixed mark of said dial, wherein said control mechanism comprises an input wheel set which is arranged to be driven by an hour wheel of said movement or by a train meshing with said hour wheel or by a date mechanism, said input wheel set comprising a finger arranged to pivot a first star wheel integral with an intermediate wheel which meshes with a transformation train to drive a stop wheel which comprises hollows arranged to cooperate with a click returned by a spring to a rest position, said stop wheel is integral with a second star wheel, whose teeth are arranged to drive pins comprised in said month display wheel set when said stop wheel pivots and to hold said pins in position when said stop wheel is kept stationary by said click in the absence of pivoting of said first star wheel.