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 similar to that found in synapsids, the tibia and fibula show greater simplicity and primitiveness. Moreover, they are notably smaller than the femur, a condition opposite to what is observed in most reptiliomorphs leading to amniotes.