Animal life began much before originally estimated

Dubai: Animal life on earth existed tens of millions of years before originally estimated, researchers have discovered.

In Oman, animal life has been found in rocks dating back to 635 million years.

"The fact that we can detect these signals shows that sponges were ecologically important on the seafloor at that time," Gordon Love, lead author of a report detailing the new findings, who works at the University of California Riverside, told the BBC.

Fossilised remains of skeletons, or even the footprints or crawl marks of animals, can usually determine the presence of ancient life in rocks.

This, however, does not apply to animals of ancient geological history because their shapes were smaller and softer. Until now scientists did not have the techniques to discover their existence.

A new method used by Love's research team was able to detect breakdown products from lipid molecules, which are important structural components in the cell membrane of animals.

Over time, these will transform, leaving a molecule known as cholestrane. For sponges, it takes a form known by scientist as 24-isopropylcholestane.

This substance was found in high concentrations in the south eastern edge of the Arabian peninsula.

The find pre-dates the ice age, scientifically termed the Marinoan glaciation. Finding animal life before this time period is viewed by many scientists as remarkable discovery.

In Love's view, the find means that the world was not entirely covered in ice as previously believed.

"I believe there were areas of what we might call refugia - areas of open ocean where biology could go on," he said.