Two groups of whales evolved massive heads for different reasons

By Jake Buehler

Bowhead and right whales are among the biggest animals alive today, but a new look at how they evolved suggests that these two closely related groups ballooned in size independently, and probably for different reasons.

Both are balaenids, a type of baleen whale (a classification that includes the gigantic blue whale), but they aren’t shaped like other baleens. They have stocky bodies and immense heads that can take up a third of their body length, and their mouths are …