No Chicken Wings

Anomalopteryx_didiformus 
J. Erxleben. M.&N. Hanhart lithograph

All genera of Moa and all species within those genera present with entirely absent pectoral girdles and forelimbs. The hindlimbs more than made up for the lack of forelimb, which is good considering the birds were all completely flightless. Not having to worry about a tail or a pair of waving wings allowed Moas to run with their enormous legs. They may not have had a fast sprint, but they certainly had robust musculature attaching to the legs. The femur is approximately half the length of the tibiotarsus. Considering that the majority of the forward sweep of bird's legs tend to be through extension of the knee joint a shorter femur does not necessarily provide a final indication of speed. The longer tibiotarsus, however, was very robust and must have possessed strong muscles that would have been able to power the legs off the ground and through their arc of movement. Moas were most likely better equipped for running across the open lands of New Zealand rather than the forests. The center of gravity would have been oriented right around the area between the knees of the bird and directly above the enormous feet. Any forelimbs would have also destroyed that center and brought the bird just enough further forward bending that any running would have been difficult if not impossible, making for a very clumsy giant.