Whales reached huge size only recently

Jonathan Amos Science correspondent

24 May 2017

Blue whales are the biggest animals that have ever existed on Earth but they only recently* got that way. 

This is the extraordinary finding from a new study that examined the fossil record of baleens - the group of filter feeders to which the blues belong. 

These animals were relatively small for most of their evolutionary existence and only became the behemoths we know today in the past three million years. 

That is when the climate likely turned the oceans into a "food heaven". 

Favoured prey - such as krill, small crustaceans - suddenly became super-concentrated in places, allowing the baleens with their specialised feeding mechanism to pig-out and evolve colossal forms. 

"The blue whales, the fins and bowheads, and the right whales - they are among the most massive vertebrates to have ever lived," explained Nick Pyenson from the Smithsonian's National Museum of Natural History in Washington DC, US. 

"Some of the dinosaurs were longer, but these big whales even outweighed the largest dinosaurs. And isn't that surprising? People kind of think of gigantism as being a fact of the geologic past. But here we are, living in the time of giants on Planet Earth," he told BBC News. 

Continued