Flippers of penguins and dolphins are an example of . . . . . . .

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

Which of the following organs is $NOT$ vestigial in humans?

Select the incorrect statement.

Which of the following is responsible for the evolution of endemic species in South America and Australia?

Fossils of $Archaeopteryx$ were found from: