Saturday, January 03, 2009

Marvelous Pre-Cambrian Fossils

If like me, you love the Burgess Shale fossils, you'll be taken with this news item: Eight-armed animal preceded dinosaurs. It's remarkable enough to find so many beautiful fossils of soft-bodied animals, but to find they are older than the "Cambrian explosion" is quite wonderful. Really, it makes dinosaurs seem recent and mundane.

[Zhu, Gehling and their colleagues] believe the animal was a soft-bodied, dome-shaped organism that lived on seabeds and fed by absorbing dissolved nutrients from the ambient environment.

Before the latest fossils were found, some researchers identified the creatures as lichens or fungus-like organisms, but Zhu and his team suspect that at least some Ediacara fossils represent now-extinct diploblastic animals, or creatures that possess only two cellular layers separated by a jelly-type substance.

"Diploblastic animals are common creatures on present day earth," he said, mentioning that jellyfish, corals and sea anemones belong to the group.

"These animals (display) radial symmetry but lack complex organs, as shown by E. octobrachiata," he adds.

The multi-armed creature, and several other early life forms, went extinct around 542 million years ago, which Zhu says, "left empty niches for the subsequent Cambrian explosion of complex animals."

Representatives of nearly all existent animals emerged at this time, when a rapid increase in oxygen made respiration and metabolism possible.

....In addition to the eight-armed creature, they describe other early living things that looked like leaves, shells, stars and something almost akin to a peace symbol.

The Discovery News report includes links to the scholarly articles, and lovely photographs.

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