قالب وردپرس درنا توس
Home / Science / The blue-whale ancestors hunted the oceans with surprisingly sharp teeth

The blue-whale ancestors hunted the oceans with surprisingly sharp teeth



Artist's impression of Llanocetus denticrenatus, an ancient forerunner of the baleen whale.
Illustration: Carl Buell

Modern blingees that deal with feeding baleen whales use comb-like structures in their mouths to collect large quantities of Itsy-Bitsy animals and microorganisms. But as new research shows, her ancestors were remarkably different, with sharp teeth that she used to attack prey.

Baleen whales, a group that includes humpback whales and blue whales, are the largest animals on earth during the late Eocene era emerge about 20 million years ago. The origin of these bull fattening animals, and how they got to their unique Bartenfiltern remains a mystery due to lack of fossil evidence. An analysis of a 34 million-year-old whale skull discovered on Seymour Island in Antarctica now provides some important new clues.

The new research shows that the ancestors of the baleen whales had sharp, widely spaced teeth and were about 26 feet long, which is actually quite large for time and for a dental whale. These old whales did not show any signs of baleen ̵

1; the keratin sieve that allows filter feeding. This suggests that Baleen originated later in history and assumed a different evolutionary path than some scientists have suggested.

This whale species is known as Llanocetus denticrenatu s. It is the second oldest Bartenwal ancestor ever discovered and is a distant relative to modern humpback whales and blue whales. The skull analysis performed by Felix Marx of the Royal Belgian Institute of Natural Sciences and R. Ewan Fordyce at the University of Otago in New Zealand shows that Llanocetus had well-developed teeth and gums. Apparently this creature was probably a terrible robber – a kind of extra-large version of contemporary orca. The results of this new study were published today in Current Biology .

Previously, scientists had discovered that Barten and the practice of filter feeding occurred when whales still had teeth. However, an analysis of Llanocetus suggests that this was not the case and that whales lost their teeth before the appearance of Barten. An intermediate feeding style, probably a suction feeding, was sandwiched between the two feeding modes.

Marx and Fordyce documented a series of grooves on the roof of Llanocetus . In modern whale-feeding filters, these grooves contain blood vessels that feed the beards. In the case of Llanocetus however, the grooves were grouped around the necks of the teeth.

"Instead of a filter, [Llanocetus simply seems to have a large gum and, as one thinks of his teeth, is primarily fed by acrid, large prey," Marx said in a statement. "Still, it was huge: with a total body length of around eight meters [26 feet] it's comparable to living whales."

Marx and Fordyce speculate that the large gums in whales like Llanocetus developed slowly to become more complex over time, eventually leading to beards. This transition only took place after the teeth had disappeared as a trait, replaced by a feeding style in which biting was replaced by the sucking in of small prey, much like some whales and dolphins do today. Baleen, the authors argue, helped the whale to keep smaller prey in its mouth more effectively.

"The giants of our modern ocean may be gentle, but their ancestors were anything but," said Marx. "Llanocetus was tall and a wild robber and probably had little to do with how modern whales behave."

"I think this is an excellent study that, in my opinion, adequately highlights the feeding and size diversity of the earliest species baleen whales," said Morgan Churchill, an expert on ancient whales from the University of Wisconsin Oshkosh, Gizmodo. "I think it convincingly shows that these earliest serrated baleen whales probably lacked baleen and did not filter feed, and I think we need to know much more about the evolution of baleen … especially with whales closer to the modern species This, however, closes an important hole in missing information about these truly early whales. "

Alistair Evans, an adjunct professor and evolutionary biologist at the School of Biological Sciences at Monash University in Australia, says this study is a long-awaited one Perfection is a description of an extremely important fossil.

"The description of this fossil is now very current because of the current debate about how baleen whales developed and how the earliest baleen whales were able to feed." Other fossils have been interpreted to bale relatively early in their evolution for filter feeding, but this new fossil is older than most of them and clearly had no beards, "said Evans Gizmodo. "This seems to be the nail in the coffin for the idea that Baleen performed early in the development of the Most Isle Bee Whale and especially for the idea that both whiskers and teeth were side by side in a whale." The authors rightly came to the conclusion that the animal had spent a lot of time consuming other marine animals catch and eat. He said that the size of the whale was also very impressive, because he was very tall so early in whale development.

"The standard story for the evolution of the largest ever-living animals was that they could become massive only through filters feeder," he said. "Since it's obvious that this was not a filter feeding animal, it's actually possible to reach that big size without being a filter feed."

Robert Boessenecker, a paleontologist at the College of Charleston, said that this research is "a long time coming" and he is thrilled with the results. But given the "very strange" mouth and teeth of this fossil, he believes that a simple interpretation of his eating habits is unjustified. Besides, he is not convinced that Baleen was born in the way the authors claim.

"It is important to note that while Llanocetus is one of the oldest mysticettes [whales]it is not the most primitive, and that a period of filtering [Llanocetus] seems to have preceded the The waters further diminished by suggesting that filter feeding for serrated baleen whales is primitive, "Boessenecker told Gizmodo. "Based on the evidence provided, Baleen may still be a viable hypothesis for Llanocetus highlighting the transition from tooth to baleene-based filtration."

No doubt there is still much to learn about whales and the origin of filter feeding. The key is to find more fossils – a daunting task given the aquatic environment in which these ancient animals lived.

[Current Biology]


Source link