GameMaker supports this type of animated sprite created using the program Spine (you can find out more about Spine here). This animation can then be ' skinned' (ie: given a texture) and drawn to the screen like a sprite. These poses can then be turned into animation key-frames, and in turn you interpolate the bone positions between each key-frame to create a smooth and very natural looking animation. The idea behind this is that you create a base ' skeleton' and then move the ' bones' to create poses. A very powerful tool for creating naturalistic sprites is to create them using skeletal animation.
