Tuesday , February 18 2020
Home / argentina / Before the whales left, they were toothless – Quartz

Before the whales left, they were toothless – Quartz

The whales about 33 million years ago were not polite. They lacked teeth, therefore, as a powerful, prehistoric vacuum, they sucked whole fish and squid, swallowing them whole.

The image of a sticky, toothless whale violates the existing evolutionary theories that ancient tooth whales for grinding on food turned into baleen – straw, keratin structures that filter tiny prey, like krill, from sea water. However, the newly documented remains of an ancient whale species suggest that whales first completely lost all their teeth, and then evolved to have a mustache. The researchers, led by a team at George Mason University in Virginia, reported on their findings in Current Biology, published today (November 29).

Researchers investigated the remains of an ancient whale, discovered in Oregon in 1977 by an amateur collector of minerals, which had been stored for decades in a warehouse in Maryland. Today, all we know about this whale was that he lived about 33 million years ago; scientists called it Maiabalaena, or mother whale.

When the team from George Mason finally got to the bones, they were surprised to find that the structure of the jaw and throat was more consistent with sucking than biting or chewing. Because Maiabalaena lived between jagged whales, which dates back 55 million years ago, and the appearance of baleen whales that arose 25 million years ago, the team believes that it represents an intermediate evolutionary step in the history of whales.

Peredo et al., 2018 / Screenshot

The evolution of feeding whales.

Maibalaena turned into toothless, because whales living at the time did not need teeth to live long enough to reproduce, says Carlos Peredo, a graduate student studying paleontology and lead author of the article.

Ancestors Maibalaena had a full set of teeth for catching and chewing prey. However, at some point they started eating small and small animals that needed less chewing – this meant that whales with teeth would no longer be reproduced than animals. In the end, however, the teeth may have prevented the absorption of feeding, or perhaps the whales without teeth needed less food than toothed whales during maturation, which made them more likely to survive. When more of these lifeless survivors reproduced, the whales completely lost their teeth.

Peredo postulates that baleen has evolved to solve the problem that feed feeders have encountered: absorb too much salt water while eating. Balin releases krill and other small prey species for ingestion, allowing the whale to push out excess water.

This work shows that evolution does not necessarily follow a direct path, but instead progresses in favor of the fact that animals must live long enough to reproduce their environment. It is inevitable that modern baleen whales will have to re-develop in order to keep up with their ocean houses, which are rapidly changing due to water warming as a result of climate change. Marine biologists are still not sure how these changes will affect their food sources or physiology. Although evolution can occur over 100 generations (blink of an eye, in biological terms), some baleen whales have been living for more than a century. With longevity, it is unclear whether they can grow fast enough to keep pace with their changing environment.

Source link