Closer closing of fossil discovered more than four decades ago has resulted in the identification of a new whale species – a 33-year-old cetaceol that does not contain tooth or pallet. Her discovery could solve a longstanding mystery about the origin of whales that feed filters, but some scientists say that the new analysis is not completely convincing.
Presentation Maiabalaena nesbittae, genes and extremely new whale species. About the size of a modern whagaga whale, the cetaceol did not have 4.57m-tooth or pale tooth (rows of hair-like plates using whales to filter a small amount of water), depending on space then on juice feeding.
As such, Maiabalaena nesbittae, which means "mammoth", a step between ancient underground whales and modern filters, according to new research published today in the Current Biology.
Today, whales can be filled in roughly to two main groups: deep whales, such as orcas and dolphins, and whales that feed (or mysticeti), such as humpbacks, fin whales, blue whales and minke whales. Baleen is the remarkable evolutionary device that allows filtering to be possible, allowing large marine whales to use several tons of daily food without having to compile or blow.
Whales are the first mammals and only to evolve Baleen, but the origin of this feeding strategy is not clear. Whales fall from terrestrial mammals, which kept their teeth after adjusting an aquatic lifestyle.
With its impressive teeth, ancient whales continued to grow their food. But the environment changed, as they were predators, so these whales had to adopt new feeding strategies. Ultimately, this came to an end to feeding whales filtering.
In terms of how whales are getting teeth to get a pallet – a substance made of keratin, which is what is hair and nail and made of it – is subject to many arguments.
Some scientists have guessed that ancient whales use their teeth for water dipping, and that this feeding strategy leads directly to Baleen. This theory took a direct hit last year by the balcony of Monash University who showed that the sharp teeth employed by ancient whales could not have been used as filters, bringing the conclusion that ancient whales were not passed through a teeth-based filtering period, and that there would be some form of mediators, species that have yet to be found must have existed.
Part of the problem is that keratin keeps not good in the fossil record. For paleontologists who are studying ancient whales, this mystery is like studying aviation in ancient animals, and a seemingly endless searching tool to discover the "missing link" between birds that are. sliding and those who can self-powerful flight.
In the case of whales, paleontologists have been looking for an intermediate species of whales that have located between deep whales and whales that feed a filter. Discovery of toothless teeth, not devoid Maiabalaena nesbittae This could be very good.
There is a partial skeleton Maiabalaena nesbittae, which has almost completed a skull, has been discovered in Oregon back in the 1970's, and has worsened in the Smithsonian national collection since then. To this point, a detailed fossil analysis was not possible because it was melted with rock and other materials.
The leading author of the new study, Carlos Mauricio Peredo from the University of George Mason and the National Natural Museum, looked at this old fossil with new eyes using top quality CT scanning technology. Looking back to the rock, the researchers were able to identify the historical signs of the flying and baleenless whales – including a higher mouth and a dad that had no proper surface to prevent balloon.
"The living Baleen whale has a large roof, in its mouth, and it has also thickened to create binding sites for the Baleen," said Peredo in a statement. "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. "
Other evidence refers to this animal as filtering foods. Muscle attachments on his throat bones suggest the presence of strong mouths and removal tongue – features that would have allowed this vaccine to suck water in its mouth, cut fish and small squid in the process.
After releasing this ability, they did no longer need their companions on these whales, so their teeth broke down gradually. Finally, the loss of teeth and origin of Baleen, the researchers, argues, where there are so-called evolutionary events.
In terms of why whales have been prevented from feeding and chewing in favor of sucking, the researchers say that it is changing by a changing environment. Maiabalaena during the transitional period the Eocene of the Oligocene, which took place around 33 million years ago. This was a crucial time for whales, as the continents moved and separated, and as the Antarctic oceanic bogs cooled the oceans.
As the planet's geology changed, so was the marine environment – and animals. Whale whales have been changed or removed, enforcing them to find new prey, which led to the process of transferring from deep feeding to sucking, researchers guess. Ultimately, about 5-7 million years later, about 26-28 million years ago, the toothmills began to boil a pallet, facilitating another transition, this moment of sucking feeding to filter feeding.
"In general, I believe that this is a good study, and I agree with its general conclusions," said Felix G. Marx, paleontologist at Monash University that was not associated with & # 39; This new research, at Gizmodo. "It is crucial, however, Maiabalaena seems to be right in the middle of this transition, with no teeth, and possibly no pallet. "
O maybe no ballet.
That's the keyword phrase here. As noted, pallet, which is made of soft tissue, is not very good fossils. Typically, scientists can find the presence of a dolphin in a fossil by looking for traces of equivalent blood vessels on their bones. And in fact, the remains of blood vessels in the Maiabalaena fossil. The question, however, is whether these blood vessels always match Baleen.
"The new study says no, and argues that similar structures also exist in spectacular whales that did not filter animal feed," said Marx. "I agree, but this is still an interpretation, and I suspect that everyone will not buy it. Luckily, there are more things we can do to go to; address this question, for example by looking at how Baleen develops in the womb ".
The University of Monash paleontontist Alistair Evans, the study author of 2017 above, agrees with the Marx assessment, saying that the absence of tooths in this species is fairly noticeable, but not a ballet absenteeism.
"As there is rarely a fossil in Baleen, his presence can seldom be seen directly," said Evans to Gizmodo. "As suggested from before – a [as this new paper] give more evidence – there are no bone money bullets that can tell us sure Baleen is present. Therefore, unfortunately, there is no strong evidence that Baleen is absent, but we can never find such evidence. "
Evans says that the conclusions made in the new study are "quite reasonable", but he would like to see other specimens of this species and those associated with them that have been saved well in the region where Baleen would be present.
"I was happy they found a fossil that we anticipated would happen, but the evidence is not slam dunk that it fits in this slot," Evans added.
So it is Maiabalaena nesbittae What's the missing link we've been looking for? Obviously, yes – but we will not know sure that more fossils will be restored.[Current Biology]