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The whales lost their teeth before developing a pallet as a hair in their mouths



IMAGE: This is an artistic reconstruction of mother and calf Maiabalaena nesbittae Offshore nursing from Oregon during the Oligocene, about 33 million years ago. Through Maiabalaena would not …
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Credit: Alex Boersma

Arisen from dinosaur development, one of the most unusual transformations in life history was the evolution of Palermo – rows of flexible plates such as hair that uses blue whales, barrage and other marine mammals to filter relatively small predation of gulps from seawater. The unusual structure allows the world's largest creatures to use several tonnes of everyday food, without ever biting or feeding. Now, Smithsonian scientists have found an important media link in the development of this innovative feeding strategy: an ancient whale that has no teeth or pallet.

In the November 29 edition of the magazine Current Biology, scientists at the National Museum of Natural History and Smithsonian colleagues describe for the first time Maiabalaena unbeaten, a whale that lived about 33 million years ago. Using new fossils analysis discovered long ago in the Smithsonian national scene, the team, which includes scientists at George Mason University, Texas A & M University and the Burke Museum of Natural History and Culture in Seattle, decided to have this teeth, 15 The heavy whale did not have a pallet, showing a surprising interactive step between the balloon whales that live today and their fascinating ancestors.

"When we talk about the evolution of the whale, textbooks tend to focus on the early stages, when whales went from land to the sea," said curator of marine fossil marine mammals. "Maiabalaena shows that the second phase of the whale evolution is equally important for evolution over the large scales. For the first time, we can now determine the source of feed feeding, one of the main innovations in whale history. "

When the whales first developed, they used to grow their teeth, just like their ancestors living in the land. As time goes on, many descendants of these early whales continued to grow their food, inheriting this feature from their predecessors. But as the oceans of their scope changed and that animals evolved, new feeding strategies, including feeding the Baleen filtering, said former National Museum of Natural History Carlos Mauricio Peredo, lead author of study that analyzed Maiabalaena fossils.

Whales were the first mammals to evolve a pallet, and no other mammal uses any anatomical structure even very similar to it to use its prey. But frustrated, palese, whose chemical composition is more like hair or nails or bones, keeps good. It is rarely found in the fossil record, leaving paleontologists without direct evidence of past or origin. Instead scientists have to rely on fossils and studies of fetal fetal development in the womb to fragment clues about the way Baleen developed.

As a result, it has not been clear whether, as they evolved, early ball whales keep their ancestors' teeth until a filter feeding system had set up. According to Peredo, early peculiar assumptions said that mammals must have toothpaste or pallet to eat – but many live whales contradict that idea. Whales have the tooth semen in their bottom mouth, but no-one is at the top, so they can not bend or blow. Narwhals are only teeth, but they do not use them for feeding. And there are some species of washed whales, despite being classified as interesting whales, with no teeth at all.

Due to its age, Peredo said, paleontologists are suspected Maiabalaena she may have important clues about the evolution of Baleen. The fossil comes from a period of massive geological change during the second phase of the evolution of the whale, around the period the Eocene period transferred to the Oligocene. With continents moving and separating, sea currents turned around Antarctica for the first time, substantially cooling the waters. The fossil record indicates that whale feeding styles have interrupted rapidly during this timeframe, with one group leading to feeding whales today and others leading to some ecologicalization.

As a result, Maiabalaena has had enough scrutiny since it was discovered in Oregon in the 1970's, but the rock and material matrix collected in the fossil still deceived many of its features. It has not been as Peras lanze the fossil finally and then explored with the highest quality CT scan technology, the most striking features became clear. MaiabalaenaToothpaste was easy to see from the preserved bone, but CT scans, who revealed fossil internal anatomy, told the scientists something new: MaiabalaenaThe upper chin was thin and narrow, making it an inadequate surface to prevent pallet.

"The Baleen whale has a large, large roof in its mouth, and it has also thickened to create attachments for the balloon," said Peredo. "Maiabalaena No. We can tell you quite steady that these fossil species did not have tooth, and it's more likely than not having a ballet either. "

Through Maiabalaena he would not have been able to hide or filter animal feed, muscle attachments on his throat bones show that he is likely to have strong mouths and removal tongue. These features would be enabled to suck water in its mouth, taking small fish and squid in the process. The ability to feed juice has rendered teeth, whose development requires a lot of energy to grow, unnecessary. Losing of teeth seems to have set the evolutionary phase of the Baleen, which raised the scientists estimated about 5 to 7 million years later.

Peredo and Pyenson see the evolution of whales key to understanding their survival in the rapidly changing seas today. As a pallet's appearance, the loss of tooth tooth is evidence of suitability, suggesting that whales could be able to adapt to challenges raised today. Still, Peredo warnings, evolutionary change can be slow to the largest whales, which have a long life span and take a long time to reproduce.

"Given the scale and rate of changes in the sea today, we do not know exactly what it will mean for all the different species of whales that feed on filters," he says. "We know they've changed in the past. Only they can keep up with how far the oceans are doing – and we change the Oceans are quite fast at the moment. "


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