Size of whale has evolved in the recent past!
Interestingly, the blue whale, the largest vertebrate ever to have existed, has recently become giants.
According to new research by scientists at the National Museum of Natural History of the Smithsonian, it is only recently in the evolutionary past of whales that they have become so huge.
In a study, published in Proceedings of the Royal Society B, marine mammal fossil healer Nicholas Pyenson Graham Slater and colleagues from the University of Chicago and Jeremy Goldbogen at Stanford University tracked the evolution of whale size through Of over 30 million years of history and found that very large whales appeared along several branches of the genéalogle tree there are about 2 or 3 million years.
Increasing ice sheets in the northern hemisphere during this period has probably changed the way food whales were distributed in the oceans and improving the benefits of large body size, scientists say.
How and why whales have become so large remains a mystery so far, in part because of the difficulties of interpreting an incomplete fossil record.
“We did not have good data,” Pyenson said. “How do you measure the total length of a whale represented by a piece of fossil?” Recently, however, Pyenson found that the width of a whale’s skull is a good indicator of its overall size. With this advance, the time had come to know the longstanding problem.
The Smithsonian has the collections of the richest and richest whales of everlasting life and work whales, and the museum was one of the few places that housed a collection that could provide the raw data needed to examine the evolutionary relationships between whales from different Sizes.
Pyenson and his colleagues measured a wide range of fossil skulls in the National Museum’s collections of natural history and used these measurements as well as published data on additional specimens to estimate the duration of remote wildlife. The fossils included in the analysis represented species that date back to the earliest whales, who lived there more than 30 million years ago.
The team used the fossil record as well as data on 13 species of modern whales to examine the evolutionary relationships between whales of different sizes. Their data have clearly shown that the large whales that exist today were not present for most of the history of whales.
“We live in a time of giants,” Goldbogen said. “Bearded whales have never been greater.”
The research team traced the difference to a change in body size evolved so there are around 4.5 million years. Not only do whales with bodies over 10 meters (about 33 feet) begin to develop around this time, but smaller species of whales have also begun to disappear.
Pyenson noted that larger whales appeared on several different lines at the same time, suggesting that mass size was somewhat advantageous during this period.
“We could imagine that whales have been gradually increasing over time, by chance, and maybe this could explain how these whales have become so massive,” said Slater, a postdoctoral fellow at the museum.
“However, our analysis shows that this idea is not confirmed – the only way to explain that whale whales become the giant it is today is so that something has changed in the recent past that made it become a giant and Made it a disadvantage to be small. “