Birds have a well-known mechanism that allows coordinated flexion and extension of the elbow and wrist. It's remarkable because it's basically automatic and energetically very efficient, drawing on the conformation of the bones, ligaments, and tendons more than active muscle contraction. Notice how extension automatically puts the wing in flight position, whereas flexion automatically folds it away. Very cool! Here Emily Caggiano, an Ohio University Honors Tutorial College undergrad working in WitmerLab, demonstrates the mechanism with the isolated wing of a Laysan albatross (Phoebastria immutabilis).