Limb Movements in a Monotreme (Tachyglossus aculeatus): A Cineradiographic Analysis

Science  19 Jun 1970:
Vol. 168, Issue 3938, pp. 1473-1475
DOI: 10.1126/science.168.3938.1473


In a walking echidna the principal movement of the humerus is long-axis rotation. The humerus remains approximately perpendicular to the sagittal plane, but the femur is directed anterolaterally at angles from 35° to 50°. In addition to long-axis rotation, the femur elevates and depresses in an arc which usually varies between 40° and 90°. The femoral angle, the femoral elevation and depression, and the plantar contact of the manus beneath the glenoid are features found also in generalized therians.