An example of a sponge fossil.
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- The fossil structure found in Canada may be 890 million years old.
- They may be the oldest animal life on earth.
- Sponges are simple animals with ancient history.
Research on Wednesday showed that the fossil structures found in northwestern Canada may come from sponges that lived in the ocean 890 million years ago, making them the earliest known animal life on Earth.
These findings also challenge the long-held view that animals appeared on Earth only after large amounts of oxygen were injected into the atmosphere and oceans.
Sponges are simple animals with ancient history. Genetic evidence collected from modern sponges suggests that they were likely to appear between 1 billion and 500 million years ago.
But until now, there is no evidence that the sponge fossils of this period are called the early Neoproterozoic.
Elizabeth Turner, a professor at the Harquel School of Earth Sciences at Laurentian University in Canada, is looking for evidence of sponges in coral reefs 890 million years ago, which are made up of a bacteria that deposits calcium carbonate.
She discovered a network of tiny tubular structures containing mineral crystals of calcite—suggesting that they were at the same time as coral reefs—very similar to the fibrous skeletons found in some modern sponges.
If the structures identified by Turner are finally confirmed as sponge samples, they will obsolete the oldest known sponge fossils by 350 million years.
Although the effects of her possible discovery were published in the journal Nature, Turner said that she was not dizzy.
“The earliest animals in evolution may be spongy. Considering that sponges are the most basic animals in the tree of animal life, this is not surprising,” she told AFP.
“The properties of this material are very similar to those of younger fossil sponge bodies,” Turner said.
She said that these possible sponges are about 1 cm wide and “may be small and inconspicuous, living in dark corners and crevices below the upper surface of the coral reef.”
If these structures are indeed confirmed to be sponge specimens, it means that they have lived for approximately 90 million years before the earth’s oxygen levels reach the level considered necessary to sustain animal life.
Turner said that if they are confirmed to be sponges, she believes they lived before the Neoproterozoic oxygenation event, during which the oxygen content increased, which subsequently led to the emergence of animal life.
“If my interpretation of the material is correct, the earliest animals appeared before that event and may have tolerated relatively low oxygen levels compared to modern conditions,” she said.
“It is possible that the earliest animals could tolerate hypoxia-some modern sponges are-but the more complex animal types that require higher oxygen levels did not appear until after the Neoproterozoic oxygenation event,” Turner added.
