Do the Pre-Cambrian Evolution Dance!
Posted on 06/03/2004 1:41:56 PM PDT by PatrickHenry
Newly discovered fossils from China seem to be the oldest multi-celled animals yet found that were complex enough to have a two-sided body plan rather than a round one.
The report on the creatures, published online Friday by the journal Science, is the latest in a series of fossil finds that downplays a supposed surge of species and diversity in body styles believed to have happened rather suddenly 540 million years ago.
The episode, known as the Cambrian explosion, has been generating controversy for more than a century because it marked the point in pre-history where fossils for virtually all of the 40-some major animal body plans suddenly appeared.
Before then, the evidence of life amounted to rare fossilized bacteria and colonies of bacteria, puzzling scientists who were trying to understand the pace of evolution. Even Charles Darwin conceded in his "Origin of Species" that the oldest fossil records didn't fit his theory of gradual, orderly evolution over time.
Many researchers now think that evolution is more episodic, influenced by mass extinctions brought about by volcanic eruptions, asteroid impacts, ice ages or other events that prune the tree of life so that it can then grow in different directions.
But many scientists also felt that fossils from pre-Cambrian times were there to be found, if only they discovered old enough rock in the right places. One of those places, it appears, is an open phosphorus mine in southern China where small, relatively soft creatures have been preserved in ancient ocean sediment called the Doushantuo Formation.
Jun-Yuan Chen of the Nanjing Institute of Geology and Paleontology has been studying specimens from the region for nearly a decade, including early sponges and eggs from those animals.
In the latest project, working with several American paleontologists to comb through tens of thousands of microfossils, Chen found 10 that clearly had bilateral shapes - a top and a bottom, with left and right sides that are nearly identical.
Although the organisms were microscopic in size - less than a fifth of a millimeter long - the scientists identified several internal organs of the animals, which were shaped like flattened turtle shells. Among the structures are a mouth, a pharynx, a gut and three-layers of skin or soft shell.
They named it a Small Spring Animal (Vernanimalcula guizhouena) because the sediment was laid down on top of glacial deposits left behind by what some researchers think was a period of near-global ice cover, dubbed "Snowball Earth."
That helps date the animals from 580 million to 600 million years old, well before the Cambrian period began, suggesting that the changes of that time had deep roots and had tiny prototypes some 40 million to 55 million years earlier.
"The genetic toolkit and pattern formation mechanisms required for bilaterian development ... long before the Cambrian," the researchers wrote. "The diversification of body plans in the Early Cambrian followed from the varied deployment of these mechanisms once conditions permitted, not from their sudden appearance just before the Cambrian boundary."
Yet another prediction of evolution theory seems to be working out. Presumably, creationist websites claiming that the Cambrian explosion contradicts evolution will swiftly publish corrections.
frgoff/g3k's gonna be po'ed.
> creationist websites claiming that the Cambrian explosion contradicts evolution will swiftly publish corrections.
Uh, yeah. I'll just hold my breath for that, shall I?
There has always been debate among paleontologistss about the Cambrian explosion. Many scientists think it is an illusion caused by gaps in the fossil record.
Oh...I thought this was about some contrarian emeritus professors in Cambridge.
I heard that just happened. It was in the same newscast wherin it was reported that Michael Moore (Jabba the Nut) returned his Palm d'Or, confessing that he wasn't telling the truth in any of his movies. I swear I heard it. Really
There are no pre-cambrian fossils.
--effdot
Hehe. I think your tagline needs to read "Agent Provocateur". Intersting article as well.
Nah. They'll just claim that this new find contradicts evolution.
Those were loooooooooong 6 days.
Right. I had forgotten the First Law of creation science: Everything proves creationism!
This is big news. The Cambrian explosion has always been troubling.
I don't think any biologists ever really lost any sleep over it. Like the article says, they assumed the stuff might show up one of these days. And if it never did, well ... the rocks are old, the fossils are fragile. Gotta live with the probability that some gaps will always be with us. From what I've seen, it was always the creationists who made the biggest fuss over it, as if it were some kind of almost-scriptural Genesis period which somehow "proved" (as everything does in creation science) that Darwin was a bufoon.
Looks to me like evolution theory changing again. This is a birds eye view of scientists trying to nail jello to a wall.
So these microscopic animals which may have dwelt in soil or been washed down explains the sudden appearance of all 40 major animal body plans?
It is nice to see so many evolutionists finally admitting that the Cambrian explosion is "troubling" and celebrating the slightest microscopic hope that your theory could be true.
Well, we either had a major gap, or we had to explain a sudden and exponential appearance of lifeforms. The latter was not really viable and it was, as you say, used as a hammer by creationists against the theory. In any event, we have a whole new set of fossils to study, and that's always cool.
I'm glad you're enjoying it.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.