Ancient whale from Peru may be most massive animal ever on Earth
Whales evolved a bit more than 50 million years ago from hoofed, land-dwelling mammals as big as a medium-sized dog.
Perucetus colossus, an early whale from Peru that lived about 38-40 million years ago, a marine mammal built somewhat like a manatee that may have exceeded the mass of the blue whale, long considered the heftiest animal on record, is seen in an undated artist's rendition. 
