Another skeletal feature that is similar in "Archaeopteryx" and modern birds is the curvature of the claws. "Archaeopteryx" possessed the same claw curvature of the foot to that of perching birds. However, the claw curvature of the hand in "Archaeopteryx" was similar to that in basal birds. Based upon the comparisons of modern birds to "Archaeopteryx", perching characteristics were present, signifying an arboreal habitat. The ability for takeoff and flight was originally thought to require a supracoracoideus pulley system (SC). This system consists of a tendon joining the humerus and coracoid bones, allowing rotation of the humerus during the upstroke. However, this system is lacking in "Archaeopteryx". Based on experiments performed by M. Sy in 1936, it was proven that the SC pulley system was not required for flight from an elevated position but was necessary for cursorial takeoff.