Laminar bone as an adaptation to torsional loads in flapping flight.

Using a new histometric method, the orientation of primary osteons was measured in the main long bones of adult mallards (Anas platyrhynchos). In the light of previous biomechanical and ontogenetic studies, a functional hypothesis is proposed, explaining the histological differences observed between long bones; laminar bone tissue, mainly found in the wing bones, may be a biomechanical adaptation to torsional loads caused by flapping flight.