most living creatures will move in a circular motion also known as an arc.
Adventure time uses an arc motion in it’s characters such as Jake and Lady Rainicorn. As their limbs “defy physics” it creates a loose and fluid motion which emphasise the something of the world. In particular Lady Rainicorn when flying uses an arc motion to progress forward.
An action is staged so it is understood it is how it is presented so the expression and action is clear to the reader. Holding a pose can exaggerate an emotion or action,elements that also come into effect are lighting, colouring and even music. Rio uses effective staging to give a platform to its characters. In this particular scene the chaotic bird infants are frightening by the protagonists arm movements. This causes the to fall on the main character. The entirely scene shows set up of the main characters exaggerated arm movements to the delayed timing of the toucans falling.
Pose to Pose and straight ahead
There are two approaches to animation. Once is straight action; having two different poses with no in-between action. The second approach is pose to pose action; in addition to have a straight action there would also be various in between poses to create a more smooth transition.
Paperman in particular would have a lot of pose to pose animation. The action of the paper airplanes do not make a straight ahead action. They contain in-between poses to create the feel that the feel the airplanes are light in weight.
Illusion of Life by Frank Thomas & Ollie Johnston