Crocodilians have an anatomically four-chambered heart, similar to birds, but also have two systemic aortas and are therefore capable of bypassing their pulmonary circulation. For example,Iguanahearts, like nearly all of thesquamateshearts, are composed of three chambers with two aorta and one ventricle, cardiac involuntary muscles. The parareptiles, whose large skull roofs had no postorbital holes, continued and flourished throughout the Permian. The pareiasaurian parareptiles reached giant proportions within the late Permian, eventually disappearing on the shut of the interval . The origin of the reptiles lies about 310–320 million years ago, in the steaming swamps of the late Carboniferous period,…