In mammals, the
humerus displays a wide
morphological variation. The size and orientation of its functionally important features, including the deltoid tubercle,
greater tubercle, and
medial epicondyle, are pivotal to an animal's style of locomotion and habitat. In
cursorial (running) animals such as the
pronghorn, the deltoid tubercle is located about a quarter of the way down the shaft, which allows for rapid but relatively weak limb flexion and extension. In
natatorial (swimming) animals such as the
North American river otter, the tubercle is located nearly halfway down the shaft, which allows for powerful limb flexion and extension. The tuberosity can be very pronounced in
fossorial (digging) animals, such as the
mountain beaver. It is very superficial in
horses. ==See also==