Scientists at Princeton University found primitive sponge fossils about a centimeter long in rocks in southern Australia. Analysis reveals that the fossilized specimen lived in the oceans 650 million years ago , making it the oldest animal on Earth .
Until now, this record was held by a Namcalathus who lived 550 million years ago and whose remains were discovered in 2000. The fossil found now would therefore exceed the age of Namcalathus by 70 million years, as explained by its discoverers in the journal Nature Geoscience .
To extract the sponge fossil from the rock in which it was calcified and embedded, the researchers had to scrape and photograph the surface in sections. Later, using a digital program, they were able to create a digital model of the fossil in three dimensions. "Creek0s that there were microbial mats that built a substrate similar to a reef and that these sponges grew on top", explain in the article Adam Maloof and Catherine Rose, co-authors of the study.
The discovery constitutes the first direct evidence that animal life already existed before and survived during the most severe ice age on Earth . This period is known as "Snowball Earth" and occurred at the end of the Cryogenic period, when most of the planet was covered by ice, the specialists emphasize.
