Biologists have linked the emergence of giant whales from the ice age

Biologists have linked the emergence of giant whales from the ice age

U.S. scientists found that the whales have acquired a modern size recently. The authors of the work published in the journal Proceedings of the Royal Society B, have traced the evolution of whales for 30 million years and found that the largest animals have reached two to three million years ago.

For a long time the question of how and why whales have become such giants remained open. “We didn’t have the right data. How to measure the length of the whale, if we have only a few bones?”, — said one of the authors, curator of the Department of fossil remains of marine mammals National Museum of natural history Nicholas Pyenson. Recently, however, he noticed that the width of the skull of the whales is a good indicator of the total length of their body.

The National Museum houses the largest collection of the bones of whales, as extinct and now existing. Pyenson colleagues measured their remains, and used published studies on this topic and got a measurement of body length for 63 13 extinct and living species of whales. Evaluations have shown that such large whales as it is now, had not existed before. “We live in an age of giants. Baleen whales have never been so big,” he admired the co-author of Pyenson, a researcher from Stanford University Jeremy Goldbogen.

The size of the whales began to change about 4.5 million years ago. At this time large whales (body length greater than 10 meters) began to grow, and the smaller extinct. Moreover, changes have affected the whales of different species, from which it follows that large size at that time gave the animals the benefits.

This could be due to the increase in the amount of ice in the Northern hemisphere during this period, which led to changes in the distribution of food. When the land was covered with glaciers, the nutrients started to get into the oceans with melt water, and their concentration was changed depending on the season. In the result it became easier to survive a big animal, which can effectively filter the krill from sea water, and migrate thousands of kilometers after the available food.

“We can assume that the whale “grew” gradually and as if by chance, perhaps, this may explain the change in their sizes. But our research shows that this is not so. The only explanation for the fact that whales have become such giants as we know them now, is that not so long ago, it became advantageous to be large, and the small size became a disadvantage,” concluded one of the authors of the article, a biologist from the University of Chicago Graham Slater.