A Canadian geologist may have discovered the oldest fossil record of animal life on Earth, according to an article in the journal Wednesday. nature.
About a billion years ago, an area of the Northwest Territories, now formed from rugged mountains, was a prehistoric marine environment where the remains of ancient sponges can be preserved in mineral deposits, the article says.
Geologist Elizabeth Turner, who works at Laurentian University in Ontario, discovered these rocks in a remote part of the Territories, accessible only by helicopter, and has been drilling since the 1980s. The thinner parts of the rock contain three-dimensional structures that resemble modern sponge skeletons.
“I think these are really ancient sponges – only this type of organism has this kind of organic filament network,” said Joachim Rittner, a geologist and sponge expert at Germany’s University of Göttingen, who was not involved in the Canadian research.
Dating the adjacent rock strata indicates that the samples are about 890 million years old, making them about 350 million years older than the oldest sponge fossils found to date.
“The most surprising thing is the age” of the fossils, said Paco Cardenas, a sponge expert at Sweden’s University of Uppsala, who was also not involved in the research. “The detection of sponge fossils dating back nearly 900 million years will greatly improve our understanding of early animal evolution.”
Many scientists believe that the oldest groups of animals on Earth included soft sponges or sponge-like organisms devoid of muscles and nerves, but they showed other characteristics of simple animals, including cells with divergent functions and sperm.
There is certainly very little scientific consensus or certainty about what may have been as ancient a billion years ago, so other researchers will likely continue to examine and discuss M.I Turner.
“I think it has a very solid record. I think it’s worth publishing — it makes the evidence available to other people,” said David Butger, a paleobiologist at the University of Southern California, who was not involved in the research.
Scientists believe that life on Earth appeared about 3.7 billion years ago. The first animals appeared much later, but scientists still do not agree on when.
To date, the oldest undisputed fossil sponge dates back to about 540 million years ago, during the Cambrian period. But scientists using the “molecular clock” estimate that sponges appeared much earlier, about a billion years ago – although there is no physical evidence to support this thesis yet.
“This will be the first time a sponge fossil has been found before the Cambrian, and not just before that, but long before that – which is the most exciting,” said Professor Cardenas, adding that the research appears to confirm estimates of the molecules clockwise.
Fossil evidence was scarce before the Cambrian, when animals first developed hard skeletons, exoskeletons, and shells, which are likely preserved in the ground.
“These types of fossils belong to more complex fauna – obviously there must be a narrative” of simpler animals, such as sponges, that first appeared on Earth, said Elizabeth Turner, author of the article.
Dating back to 890 million years ago is important, because if the identification of sponges is confirmed, it will appear that the first animals evolved before the time when the oxygen in the atmosphere and oceans reached a level that scientists thought was necessary for the animal. life. However, recent research shows that some sponges can survive on very little oxygen.
“Everything on Earth has an ancestor. The first evidence of animal life has always been expected to be small and cryptic, which is very accurate evidence,” said Roger Sommons, a geologist at MIT, who was also not involved in the research.
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