Whales today are bigger than ever before

It might not seem like it, but we live in a world full of giants. Blue whales are the largest animal ever to move across the planet, with the biggest measuring in at over 100 feet long and weighing hundreds of thousands of pounds.
Blue whales are part of a group called baleen whales, distinguished today by their baleen, a screen of cartilage that hangs down from the roof of their mouth in place of teeth used to filter prey out of the water. Baleen whales lost their teeth gradually, replacing them fully with baleen about 20 million years ago. We know a lot about baleen whales, which include blue whales, humpbacks, and right whales among others, but why—and when—did they grow into giants?
In a paper published Tuesday in the Proceedings of the Royal Academy B, researchers examined the fossils of over 140 baleen whales representing 13 modern species and 63 extinct species to figure out when and why they got so large.

Whales today are bigger than ever before. Now, we know why.