Radius (bone) ulna (center of the circle) to the edge of the radius (the circle). The ulna acts as the center point to the circle because when the arm is rotated the ulna does not move. In four-legged animals, the radius is the main load-bearing bone of the lower forelimb. Its structure is similar in most terrestrial tetrapods, but it may be fused with the ulna in some mammals (such as horses) and reduced or modified in animals with flippers or vestigial forelimbs. Radius (bone) The radius or radial bone is one of the two large bones of the forearm, the other
Keilhauia probable portion of the ischiopubis that represents the pubis is thicker than the rest of the bone. Also uniquely among ophthalmosaurids, this fused element is shorter than the femur. Both ends of the femur of "Keilhauia" are approximately the same width, with the middle of the femoral shaft being slightly narrower. The top end was slightly thicker than the rest of the bone along its front rim. Like "Arthropterygius" but unlike "Ophthalmosaurus", the femoral dorsal and ventral processes were rather reduced. At the bottom end, there are two facets, one for the tibia and one for the fibula; this is