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CROCODILES HAVE FOUR CHAMBERS STILL IT IS CALLED AS REPTILIA
In the crocodile heart, the partition between the right and the left ventricle has been completed and resembles the four-chambered heart of birds and mammals. Nevertheless a peculiar difference from the four chambered hearts does exist. Specifically, the right ventricle pumps blood into not one but two separate vessels: the pulmonary artery and the, so-called, right systemic artery. Such an arrangement allows the crocodile to effectively switch between normal and low oxygen (apnea) conditions by closing the pulmonary circulation.
The crocodile's heart is a slight modification of the ancestral reptilian state says the scientists ,and  may be it  is evolutionary biology.
As Liem and Walker explain: "the ancestors of birds had a heart and pattern of aortic arches similar to that of crocodiles. Because birds evolved endo- thermy and lungs that are continuously ventilated, shunts bypassing the lungs--as found in crocodiles--would have had no adaptive value. Equal volumes of blood are sent to the lungs and body at all times, which appears to have been simply the result of the loss of the left systemic arch." This hierarchical pattern of similarities is exactly what would be expected from an evolutionary process.


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