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All whales and dolphins are descended from terrestrial mammals, ancient creatures that were very similar to the modern hippopotamus. Now, a fascinating new genetics study shows the incredible evolutionary changes these animals had to experience to become the perfectly adapted marine animals we see today.
Biologists aren't entirely sure which creature modern cetaceans (dolphins, whales, and porpoises) are descended from. The traditional theory suggests mesonychids, an extinct order of carnivorous ungulates (hoofed animals) which resembled wolves. But more recent genetic analysis points to artiodactyls, a hippo-like creature. Regardless, all cetaceans were land mammals at one point in their evolutionary history — and they had to undergo some rather remarkable changes to adapt to underwater life.
Recently, researchers from Korea Institute of Ocean Science and Technology, Korea Genome Research Foundation, BGI, and other institutes, performed a comprehensive analysis of the genomes of several cetaceans, including the minke whale, fin whale, bottlenose dolphin, and a finless porpoise. They did so to improve their understanding of the evolutionary changes required for terrestrial mammals to adapt to the ocean — but at the level of the genome.
An adolescent female Tyrannosaurus rex died 68 million years ago, but its bones still contain intact soft tissue, including the oldest preserved proteins ever found, scientists say.
And a comparison of the protein's chemical structure to a slew of other species showed an evolutionary link between T. rex and chickens, bolstering the idea that birds evolved from dinosaurs.
It has crossed my mind a few times in the past, just how could it have been that dolphins, whales and other such creatures, 'returned' to the sea, after being land animals.