D:\Program Files\AliasWavefront\Maya4.5\docs\en_US\html\UserGuide\Anim\KeyAnimSetKey11.html
там вроде все и написано...
Maya provides smooth quaternion interpolation of animated rotations. -------=This prevents the gimbal lock=----- and flipping problems that are sometimes encountered with Euler angle interpolation. Maya also supports Euler angle interpolation for cases where you prefer Euler interpolation, and for pre-4 Maya scene files.