NEET BIOLOGY

Detailed explanation-1: -The ancestor of today’s whales, the first cetacean, is believed to be Pakicetus, a quadruped measuring 1 to 2 metres long. Skeletons discovered in Pakistan indicate that the animal had typical artiodactyl ankles and a typical cetacean skull.

Detailed explanation-2: -Their land-dwelling ancestors lived about 50 million years ago. Meet Pakicetus, a goat-sized, four-legged creature that scientists recognise as one of the first cetaceans (the group of marine animals that includes dolphins and whales).

Detailed explanation-3: -To swim, they move their tails up and down, rather than back and forth as fishes do. This is because whales evolved from walking land mammals whose backbones did not naturally bend side to side, but up and down.

Detailed explanation-4: -But scientists knew that whales descended (evolved) from four-footed land mammals because whales and dolphins still have some features of land mammal: they use lungs to breathe air and give birth to young that are nursed by milk.

Detailed explanation-5: -The “first whale, ” a creature whose lifestyle (living on land but eating fish from the nearby sea) represented the early stage of this transition into the water, was a wolf-size fish eater that lived about 50 million years ago on the edges of the ancient Tethys Sea, according to the exhibit.