This is a composite video, showing two orthogonal high-speed xray views of a Seba's short tailed fruitbat taking off from the ground and transitioning into vertical ascending flight towards a landing area (out of view). Onto the biplanar high speed videos, the researchers rotoscoped the micro CT scans of scapulum (shoulder-blade), humerus (upper arm bone) and radius (lower arm bone). In this way, they achieved a new set of raw measurements, showing how the mammalian scapulum moves a lot during flight, involving both translations and rotations. The researchers also used this XROMM model to understand how the biceps muscle tendon unit changes length. Like in humans, the biceps spans both the shoulder and elbow joints. This anatomy represents a biomechanical problem, because measuring elbow flexion and extension does not reveal the length of the whole muscle tendon unit. Therefore, the researchers needed the XROMM model to understand biceps contraction biomechanics, which helped them reveal that the biceps tendon is being stretched during a wingbeat cycle.