In the developmental history of mammalian heart, it is observed that it passes through a two-chambered fish like heart, three-chambered frog-like heart and finally four-chambered stage. To which hypothesis can this above cited statement be approximated?

In the developmental history of mammalian heart, it is observed that i

1.	In the developmental history of mammalian heart, it is observed that it passes through a two-chambered fish like heart, three-chambered frog-like heart and finally four-chambered stage. To which hypothesis can this above cited statement be approximated?
Answer» In the developmental history of mammalian heart, it is observed that it passes through a two-chambered fish like heart, three-chambered frog-like heart and finally four-chambered stage. To which hypothesis can this above cited statement be approximated?