We also found that the femur is shorter than the tarsometatarsus in terrestrial birds while the reverse is true in arboreal birds.

• 树栖鸟类后肢骨骼中股骨的长度要长于跗跖骨。鸟类后肢3块骨骼的长度比例特征是鸟类长期对栖息等行为适应的结果。