Although the femur is generally similar to that of synapsids, the tibia and fibula are much more simple and primitive. In addition, they are noticeably smaller than the femur, a condition reversed to the trend in most reptiliomorphs leading to amniotes.
Despite the femur being generally comparable to that found in synapsids, the tibia and fibula exhibit greater simplicity and primitiveness. Moreover, they are significantly smaller than the femur, a situation contrasting with the trend seen in most reptiliomorphs leading to amniotes.