Tuesday , June 28 2022

smooth balance, a & # 39; 33 million years can & # 39; be "Evolutarju Missing Link"


Closer examination of & # 39 fossil, found more than four & # 39; years ago led to the identification of & # 39; & # 39 new species; whales – cetacean of & # 39; 33 million years seems neither serrated nor baleen. Its discovery can & # 39; solve longstanding mystery about the origin of whales filter filters, but some scientists say that the new analysis is not entirely convincing.

The introduction Maiabalaena nesbittae, Entirely new genus and species of & # 39; ancient whales. Roughly the size of & # 39; modern beluga whale, this certificate of cetacean & # 39; 4.57m long with no teeth or baleen (rows & # 39; plates resembling hair using the whale to filter tiny prey from the water).

As such, Maiabalaena nesbittae, Which means "whale whale", represents an intermediate stage between the ancient whale with teeth and modern filters, according to new research published today in Current Biology.

Today, the whales can be spread in & # 39; two main groups: toothed whales, such as orcas and dolphins, and whales flying filters (or mysticeti), as Humpbacks, whale fine, blue whales and minke whales. Baleen is remarkable evolutionary invention makes it possible to filter feed, which allows large sea whales consume several tons & # 39; daily food without ever having to drilled or chewed.

Whales are the first and the only mammals to evolve baleen, but the origin & # 39; this strategy & # 39; feed is not completely clear. Whales are derived from terrestrial, maintaining their teeth after taking a style of & # 39; aquatic life.

Foot their razor sharp, the ancient whale continued to chew their food. But the environment has changed, as have their prey, so these whales have had to adopt new & # 39; feeding strategies. Eventually, this resulted in the development of & # 39; whales flying filters.

How the whale went from teeth to have the baleen – a substance made of keratin, hair and nails and she made it – is subject to & # 39; much controversy.

Some scientists speculate that ancient whales used their teeth to recognize the water, and that strategy & # 39; led directly to feeding baleen. This theory has direct success of last year paleontologi of & # 39; Monash University showed that the sharp teeth of the old whale could not be used as filters, and concluded that the ancient whale never undergone phase & # 39; filtering based on teeth and some sort of & # 39; intermediate species, yet to be found to be existed.

Part of the problem is that the keratin does not hold good in the fossil record. For paleontologi studying ancient whales, this mystery is similar to flight in studying ancient animals, and that seems endless quest to find the "missing link" between birds flying and able to drive themselves.

In the case of whales, the paleontologi were looking intermediate species & # 39; whale placed between toothed whales and whale flying filters. The discovery & # 39; the toothless, baleenless Maiabalaena nesbittae you & # 39; is this missing link.

The part – skeleton & # 39; Maiabalaena nesbittae, Which includes nearly complete skull, was discovered in & # 39; Oregon back in the 70s, and recognized in the national collection of the Smithsonian since. Up to this point, detailed analysis of the fossils was not possible because it was submerged rocky and b & # 39; other materials.

The main author & # 39; the new study, Carlos Mauricio Peredo of & # 39; George Mason University and the National Museum & # 39; Natural History, looked at this old fossil b & # 39; new eyes using advanced technology TK. When addressing the rocks, the researchers were able to identify the tell-tale signs of & # 39; whales and toothless without baleenless – including jaw & # 39; thin and narrow that there was no surface which could & # 39; suspend the baleen.

"The living baleen whale has a large and wide roof & # 39; in his mouth, and he also imħaxxen to create sites & # 39; for baleen fitting", said Peredo f & # 39; statement. "Maiabalaena do so. We can say quite conclusively that this fossil species had no teeth, and it is more likely than not that did not have the baleen. "

Points & # 39; other evidence for this animal as a filter feeder. The accessories muscles on the bones of their throat imply the presence of & # 39; strong cheeks and tongue to fly back – features that enabled this whale to suck & # 39; water into her mouth, prevent small fish and squid in the process.

Equipped with & # 39; this ability, these whales m & # 39; still needed their chompers, so their teeth gradually faded away. The eventual loss of teeth and the origin of baleen, the researchers argue, so far, separate evolutionary events.

On why the perforated whale abandoned by taste and masticar for sucking, researchers say it was forced upon them transition from a changing environment. Maiabalaena lived during the transitional period divided by the Eocene Oligocene, which occurred some 33 million years ago. This was a critical time for the whales, because the continents have shifted and separated, and because ocean currents from the Antarctic cool ocean.

As the geology of the planet changed, the environment & # 39; ocean also made – and his animals. The toothed whales prey changed or disappeared, and ġiegħlithom find new prey, resulting in the transition from toothed to shoot & # 39; sucking, the researchers speculated. Eventually, about 5-7 million years later, around 26-28 million years ago, the baleen whales without tooth began to emerge, and b & # 39; thus facilitating another transition, this time from feeding & # 39; the -irdigħ to filter feed.

"B & # 39; In general, I think this is a good study, and I agree with his general conclusions," Felix G. Marx, palaeontologist at the University & # 39; Monash not affiliated with & # 39; this new research, told Gizmodo. "B & # 39; Crucially, though, Maiabalaena seems to be right in the middle of & # 39; this transition, without teeth, and possibly no baleen. "

Possibly no baleen.

That is the key phrase here. As noted, baleen, which is composed of soft tissue, it makes a great fossilis. Typically, scientists can detect the presence of & # 39; baleen seeking fossil traces of & # 39; corresponding blood vessels on their bones. And indeed, traces of & # 39; blood vessels were found in Institute Maiabalaena fossil. The question, however, is whether these blood vessels is always jikkorrelatawx & # 39; baleen.

"The new study says no, arguing that similar structures also exist in virtue of ancient whale teeth to b & # 39; clearly not ffiltrawx stuff," said Marx. "I agree, but it remains an interpretation, and I suspect that not everyone buy. B & # 39; good fortune, there are more things we can do to address this issue, for example by nisamina as baleen actually develops in the womb."

The paleontologu Monast University of Alistair Evans, co-author of the 2017 study mentioned previously, agrees with the assessment & # 39; Marx, said the lack of & # 39; teeth in & # 39; this species is quite evident, but the lack of & # 39; baleen not so.

"Because so much is rarely fossilized baleen, its presence is rarely & # 39; account directly," said Evans Gizmodo. "As suggested before – and [as this new paper] give further evidence – m & # 39; there are no silver bullets bone can & # 39; to let us know that there was a baleen. So unfortunately m & # 39; there is no strong evidence & # 39; baleen to be absent, but we also never can & # 39; find such evidence. "

Evans says that the conclusions made in the new study are "reasonably affordable", but would like to see samples of & # 39; this species and related are best preserved in the region where the baleen would be if present.

"I'm glad I have found fossils that we predicted would take place, but the evidence is not a slam dunk really tajret f & # 39; this slot", added Evans.

so he Maiabalaena nesbittae The missing link was looking for? Quite possibly yes – but will not be sure until more fossils are recovered.

[Current Biology]
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