Whales Only Recently Evolved Into Giants
Gigantism seems like a past phenomenon, given that enormous animals such as Megalodon and Tyrannosaurus rex died out millions of years ago. The largest vertebrate that has ever lived, however, is part of the present, and not past, animal kingdom. The distinction goes to the blue whale, which can reach lengths of over 100 feet.
The researchers theorize that when ice sheets began to cover the Northern Hemisphere at the start of the Ice Age, run off from the new ice caps would have washed nutrients into coastal waters at certain times of the year. This would have seasonally boosted food supplies.