They are only a centimeter long, but they are probably the remains of the oldest known form of animal life on Earth. Fossil-like structures have been discovered in the northwest of the People’s Republic of China Canada. According to a study published Wednesday, they lived in the oceans 890 million years ago. This discovery challenges the old theory that animals only emerged after large amounts of oxygen were injected into the atmosphere and oceans.
sponges are simple animals With an old story. Genetic analysis of modern sponges suggests that they may have appeared between 1 billion and 500 million years ago. But no sponge fossil from this period, known as the Cenozoic, has yet been discovered.
Possible record of 350 million years
Elizabeth Turner, a professor at Canada’s Laurentian University, searched for such fossils in the geological strata of coral reefs dating back 890 million years, reefs “made” by bacteria on which calcium carbonate was deposited. The researcher identified small tubular structures there, containing contemporary corals’ calcite crystals, which are very similar to the skeleton found in modern sponges.
If this discovery was published in the journal natureSure enough, these fossils will be 350 million years older than the oldest known so far. Perhaps the oldest animal that appeared in an evolutionary process was the sponge. This is not surprising given that sponges are the simplest animals in the animal tree of life.
‘Too small and discreet’
If the fossils you found were indeed sponges, then the latter measured about one centimeter. She explains that she was “small and inconspicuous, living in the dark and hollow folds beneath the outer surface of the reef.” They would have lived about 90 million years before the level of oxygen on Earth reached levels believed to be necessary for the emergence of animal life. Thus before the oxygenation of the modern animal occurred.
“If my interpretation of the ‘material’ found is correct, the first animals appeared before this event and would tolerate relatively low oxygen levels compared to current conditions,” Professor Turner said. She considered, “It is possible that the first animals tolerated a low level of oxygen, as is the case with some present-day sponges.” But more complex animal species could emerge only after the oxygenation of modern living.
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