Wednesday, February 04, 2009

Chemical Traces Hint Sponges Predate Snowball Earth

Chemical traces left in 635 million-year-old rocks in Oman provide the earliest evidence so far of animal life, researchers said Wednesday.

[...]

"There is a great wealth of evidence these sponges were the first multi-cellular organisms to exist."

Using a chemical analysis of molecules in rocks dated to 635 million years ago, the researchers discovered a modified form of cholesterol only produced by the sponges.

This suggests the creatures existed before a monstrous ice age that occurred around 630 million years ago, an interesting finding because many scientists believe the frozen periods spurred the development of complex forms of life, Summons said.

These simple forms of animal life came about 200 million years before land plants appeared on Earth, Summons added. The first single cell bacteria and other similar forms of life appeared around two-and-a-half billion years ago.

The oldest visible fossils of animals found in rocks are 580 million years old but the findings from this paper published in the journal Nature show that looking at molecular evidence is also key to better understanding evolution, he said.


hmmm. This one needs to have the paper before I'll say more than hmm. (wish eureka alert ad had this one up first)

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