Earth's first ecosystems were more complex than thought

Some of the first large organisms on the Earth formed ecosystems that were much more complex than previously thought, an analysis of the feeding habits of a 555-million-year-old organism revealed.

An international team of researchers from Canada, Britain and the US studied fossils of an extinct organism called Tribrachidium, which lived in the oceans some 555 million years ago.

Using a computer modelling approach, they were able to show that Tribrachidium fed by collecting particles suspended in water. This is called suspension feeding and it had not previously been documented in organisms from this period of time.

Tribrachidium lived during a period of time called the Ediacaran, which ranged from 635 million to 541 million years ago.

This period was characterised by a variety of large, complex organisms, most of which are difficult to link to any modern species.

It was previously thought that these organisms formed simple ecosystems characterised by only a few feeding modes, but the new study suggests they were capable of more types of feeding than previously appreciated.

"Our study has shown that Tribrachidium and perhaps other species were capable of suspension feeding. This demonstrates that, contrary to our expectations, some of the first ecosystems were actually quite complex," said Simon Darroch from Vanderbilt University, US.

"The computer simulations we ran allowed us to test competing theories for feeding in Tribrachidium. This approach has great potential for improving our understanding of many extinct organisms," said Imran Rahman from University of Bristol, England.