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Climate-driven extinction made the teeth of mammals even more unusual


The earth was warm 34 million years ago — it’s a winner. The supercontinent is divided. The dinosaurs were already gone. But in Antarctica there were forests where ice was not available. Some continents look like the cracked and dirty ones that are here. Mammals were everywhere — especially monkeys and rats. “From New York to Los Angeles to Canada, it roams the trees,” says Seiffert, a North American monkey. But when this deception happened 34 million years ago, they all disappeared.

Some scientists believe that carbon dioxide levels plummeted, resulting in lower temperatures and lower Antarctica. Excessive sunlight in the glaciers resulted in extreme temperatures. The transition from the Eocene to the Oligocene has been described as the transition from the “greenhouse” to the “ice house”.

Then, things got worse in Africa. Nearly 31 million years ago, volcanoes near the equator, in modern-day Ethiopia, erupted into a series of catastrophic smoke and constant melting of molten basalt.

Ancient North American, European, and Asian manuscripts are well-established 11 million years before and after that. Scientists can calculate the fossil record, which shows that animals existed before, during, and after the winter, and that they disappeared. But, Seiffert says, “at the moment, the ancient burial in Africa is a lot.” This inconsistency puzzled him, so his team tried to analyze the relationships between any of the old records he had.

In the study, Seiffert and de Vries focused on a family that began 76 million years ago, when monkeys and rats separated. In particular, he studied the teeth of two groups of rats (hystricognath and anomaluroid) and two suborders of monkeys (strepsirrhine and anthropoid). These groups produced existing species such as capybara, scaly-tailed flying squirrels, lemurs — and us.

The researchers decided to reconstruct the phylogeny — or a family of evolutionary relationships — of these groups from 56 million to 15 million years ago. Using teeth as a guide for “who is who,” he drew a line between generations from ancient fossils found in late Eocene to their children who survived the Miocene, about 20 million years ago. Upon completion, a major difference emerged: The Miocene generations descended from a surprisingly small population of ancient mammals. The researchers found that 63 percent of the generations that lived in the end of the Eocene did not pass until later. Nearly 30 million years ago, they suggested that extinction might occur because of climate change. “There are no other explanations,” Seiffert said. “It must have gone away.”

Genetic diversity gave the group a broad picture of the number of species lost through climate change, but not of the diversity of those species — in other words, the number of species. anatomic various extinct, too. For example, says de Vries, consider the extinction of two species of birds. The two types may be very similar, or they may be very different depending on body type, genetics, or environment. He said: “If you have a hummingbird and a flamingo, then it is very different from a pigeon and a dove.


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