What were the characteristics of life forms that had been fossilised?

Which bird possesses teeth in its beak?

The flippers of a seal are modified .......

Select the correct option for the forelimbs of whales, bats, cheetahs, and humans.

In the embryos of all vertebrates,including humans,a row of vestigial gill slits appears behind the head,but they function only in fish and not in other adult vertebrates. This observation was challenged by which scientist?

Fossil $X$ is considered to have evolved before fossil $Y$. This is true if: