Explanation:
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. ... Whales do the same thing as they swim, showing their ancient terrestrial heritage.
Cetaceans are fully aquatic marine mammals belonging to the order Artiodactyla, and branched off from other artiodactyls around 50 mya (million years ago). Cetaceans are thought to have evolved during the Eocene or earlier, sharing a closest common ancestor with hippopotamuses.
They are living organisms. Not a very good question is there more to it
1. A !! Its Mesozoic era and Jurassic period !!
2.B !! Archaeopteryx led to evolution of birds as they are connecting link between birds and reptiles.
3.B !! Very popular to be known , dinosaurs extinct due to metroites collision !!
Erosion: When nature or things break apart of deform themselves along with nature's affects?
