 Aetosaurs had a " pillar @-@ erect " erect limb posture similar to that seen in Rauisuchia , a related group of Triassic archosaurs . A pillar @-@ erect limb posture is one where the femur articulates vertically with the acetabulum of the hip , which is angled downward , so that the leg is positioned beneath the body and acts as a pillar bearing weight . While the limb posture is similar to rauisuchians , the feet resemble those of phytosaurs ( crocodile @-@ like semiaquatic crurotarsans ) in the retention of primitive characteristics . Although the forelimbs are much smaller than the hind limbs , all aetosaurs were quadrupeds . 
