New answers tagged mammals
I think you're looking at this the wrong way. Animals evolve to fill niches. Many, many land animals returned to the water as a place to live, including: whales, dolphins, porpoises, seals, sea lions, walruses, manatees, dugongs, otters, hippos, pygmy hippos, crocodiles, sea snakes, sea turtles, river turtles, river snakes, etc. etc. etc. Their ...
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