How whales became biggest animals on Earth found
WASHINGTON: Whales – the largest animals on the planet – have evolved to gigantic sizes only about 2-3 million years ago due to changes in the distribution of food in the oceans, according to a new study released today.
Blue whales have a record maximum weight of 173 tonnes and can reach 29.9 meters in length. However, there are a few million years, whales have rarely increased more than 10 meters.
Researchers, including the National Museum of Natural History in the US, measure a wide range of fossil skulls.
Fossils include older whale species that have lived there for more than 30 million years.
Using these measures, as well as data on additional samples, the researchers calculated the duration of 63 species of extinct whales.
They found that large whales appear along several branches of the genereal tree about 2 or 3 million years ago.
The data also showed that the large whales that exist today were not present for most of the history of whales.
“We live in a time of giants. Bearded whales have never been greater,” said Jeremy Goldbogen of Stanford University in the US.
In the study published in the journal Proceedings of the Royal Society B, researchers tracked the difference with respect to a change in body size evolved so that there are about 4.5 million years.
They found that not only whales with bodies over 10 meters beginning to change around that time, but smaller species of whales have also begun to disappear.
“The only way to explain whale whales to become the giant it is today is so that something has changed in the recent past that has created an incentive to be a giant disadvantage and made of being small,” said Graham of the University of Chicago in the U.S.
The researchers said that the evolutionary change, which took place in the early ice age, corresponds to climate change that has reconfigured the food supply of whales in the world’s oceans.
Before the ice sheets begin to cover the northern hemisphere, food resources were fairly evenly distributed in the oceans.