Theropods are not closely related to dicynodonts. Theropods are diapsid reptiles, but dicynodonts are therapsid reptiles. Cynodonts are also therapsids. We know that birds and mammals have different arrangement of the aortas. Both birds and mammals have 4 chambered hearts, and both pump blood to the lungs with the right ventricle. Both pump blood to the rest of the body with the left ventricle. The main difference is in the aorta, the main artery that routes blood from the heart to the rest of the body. The mammalian aorta is on the left side of the heart and pointed upward. The avian aorta is on the right side of the heart and arched downward. The avian aorta carries blood to the liver, stomach, kidney, intestines and legs. The avian aorta does not carry blood to the brain or wings; a separate artery branches off the left atrium next to the avian aorta to carry blood to the brain and the wings.
We don't know if the dicynodonts have 4 chambered hearts or not, since they are not closely related to the therapsids that are ancestral to the mammals. The cynodonts are close to the ancestor of mammals, so their hearts may be more similar to those of mammals than are the dicynodonts. The theropods may or may not have 4 chambered hearts. We simply do not know because soft body parts are rarely preserved. We also do not know when birds evolved their 4 chambered hearts, so we have no way of knowing whether theropods had 4 chambered hearts or not. Even if they do, we still have no way of knowing whether their 4 chambered hearts are similar to those of birds because of common ancestry or if they evolved a 4 chambered heart independently of birds.