They are only a centimeter in length, but they may be the remains of the oldest living creatures on earth. Fossil structures similar to sponges have been found in the Northwest Canada. They lived at sea 890 million years ago, according to a study released Wednesday. This discovery challenges the long-held theory that animals appeared only after large amounts of oxygen were released into the atmosphere and oceans.
Sponges are simple animals With an old story. Genetic analysis of modern sponges indicates that they appeared a billion to 500 million years ago. But no sponge fossil has yet been found from this period known as the Neoproterozoic Era.
350 million years broken record
Elizabeth Turner, a professor at Laurentian University in Canada, searched for such fossils in the geological layers of rocks as early as 890 million years ago, when they were “rocked” by bacteria that deposit calcium carbonate. The researcher identified small tube structures with calcite crystals similar to the skeleton-like rocks found in modern sponges.
This finding, if published in the journal Natural, Confirmed, these fossils are over 350 million years old, the oldest known to date. “The oldest animals that appeared in evolution were probably sponges. This is not surprising considering that sponges are simple animals in the tree of animal life,” he explained.
“Very small and sensible”
If the fossils she discovered were actually sponges, the latter measured one centimeter. They are “small and obscure, living in dark folds and crevices beneath the outer surface of the rock,” he explains. They would have lived about 90 million years before the level of oxygen on Earth reached the level believed to be essential for the origin of animal life. So before the antioxidant event of Neoproterozoic.
“If my interpretation of the discovered ‘substance’ was correct, the first animals that appeared before this event would tolerate low oxygen levels compared to current conditions,” said Professor Turner. “Like some current sponges, it is possible for first animals to tolerate low levels of antioxidants,” he thinks. But more complex animal species appear only after the occurrence of neoproterozoic oxygenation.
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