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Home / argentina / Newly-described fossil kit in museum collections reveals a surprising interstard in their evolution – ScienceDaily

Newly-described fossil kit in museum collections reveals a surprising interstard in their evolution – ScienceDaily



Opposing the evolution of the dinosaurs' feathers, one of the most unusual transformations in the history of life was the evolution of baleenic ranks of flexible hair like blue whales, shrubs and other marine mammals that used to filter a relatively small prey of ocean water gulps. An unusual structure allows the world's greatest creatures to consume a few tons of food every day, without chewing or chewing. Now, Smithsonian scientists have discovered an important mediation link in the evolution of this innovative feeding strategy: an ancient kit that had no teeth or baleen.

In the November 29 issue of the magazine Current biology, scientists at the Smithsonian National Natural History Museum and colleagues describe it for the first time Maiabalaena nesbittae, a kit that lived 33 million years ago. Using new methods for analysis of long-revealed fossils located in the Smithsonian National Collection, a team involving scientists at George Mason University, Texas A & M University, and Burke's Natural History and Culture Museum in Seattle, found that it was without teeth, 15 in the zalaska the whale probably did not baleen, showing the surprising step between the ballads of whales that live today and their deceased ancestors.

"When we talk about whale evolution, textbooks focus on early stages when whales left the sea," said the Curator of the Fossil Sea Mammal National Museum of Natural History. "Maiabalaena shows that the second stage of kite evolution is equally important for evolution through large scales. For the first time, we can now discover the origin of food filtration, which is one of the major innovations in the history of whales. "

When the whales first developed, they used their teeth to chew food, just like their ancestors dwelling on land. As time passed, many offspring of these early whales continued to chew food, inheriting this trait from their predecessors. But as the oceans around them have changed, and the animals have developed, there is indeed a new feeding strategy, including food for the baleens filter, says National Museum of Natural History Carlos Mauricio Peredo, the lead author of the study that analyzed Maiabalaena fossils.

The kits were the first mammals that developed in the baleal, and no other mammal used any anatomical structure even in a similar way to consuming their prey. But, frustrating, baleen, whose chemical composition is more like hair or nails than bones, does not keep it well. It is rarely found in fossil record, leaving a paleontologist without direct evidence of his past or origin. Instead, scientists had to rely on the conclusions from the fossils and to study the development of fetal kits in the womb to get clues as to how baleen developed.

As a result, it was not clear whether the early baleen whales had kept their ancestors teeth until a food filtration system was established. The early initial assumption, Peredo said, was that mammals living in the ocean must have the necessary teeth or baleen to eat – but several live whales contradict that idea. Sperm kits have teeth in their lower jaw but no one at the top so they can not bite or chew. The only tooth of Narwhala are their long teddy bears, which are not used for feeding. And some types of whale kits, although classified as a toothed whale, do not even have tooth.

Because of his age, Peredo, suspected paleontologists said Maiabalaena may have important clues about the evolution of the baleen. Fossil comes from a period of great geological change during the second major phase of whaling evolution, around the time of the Eocene era is a transition to oligocene. With continually changing and separating continents, ocean currents circulated for Antarctica for the first time, significantly cooling water. Fossil records indicate that swarming styles of whales have been rapidly erased in this time period, with one group leading to today's filter feeding whales and the other leading to echolocation.

According to, Maiabalaena has been well-watched since it was found in Oregon in the seventies of the last century, but the stem matrix and the fossilized material still blurred by many of its features. Only when Peredo finally cleansed the fossil and then looked at it with the latest state-of-the-art CT technology that became clear. MaiabalaenaThe lack of teeth was evident from the preserved bone, but the CT recorders, who discovered the inner anatomy of the fossils, said something new to the scientists: MaiabalaenaThe upper jaw was thin and narrow, making it an inadequate surface for which to stop the baleen.

"The Life Kit Kit has a large, wide roof in the mouth, and is also thick enough to create binding sites for the baleen," Peredo said. "Maiabalaena not. We can proudly say that these fossil species do not have teeth, and there is probably no baleal. "

While Maiabalaena he would not be able to chew or filter food, the ear plugs of muscles suggest that he probably had strong cheeks and tongue. These traits would allow him to suck the water in his mouth, taking fish and small squid in that process. Ability to suckle food would have teeth, whose development requires a lot of energy to grow, unnecessary. It seems that tooth loss has set the evolutionary stage for baleen, which scientists estimated about five to seven million years later.

Peredo and Pyenson saw how they studied the evolution of whales as key to understanding survival in today's fast-paced oceans. Like baleenes, the loss of teeth in whales is proof of adaptability, which suggests that whales can adapt to the challenges set today in the ocean. Nevertheless, Peredo warns that evolutionary change may be slower for the largest whales, which have a long life span and last for a long time to reproduce.

"Given the size and speed of ocean changes today, we do not know exactly what this means for all kinds of filter kits," he said. "We know they've changed in the past, it's only a matter of keeping pace with what the oceans are doing – and now we're changing the oceans pretty quickly."


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