Oldest fossils of large seaweeds, worm-like animals tell story of ancient oxygen

Feb 23, 2011
This cluster of fossils from the Lantian area was preserved and unearthed in very high densities. Credit: Zhe Chen and Xunlai Yuan

Almost 600 million years ago, before the rapid evolution of life forms known as the Cambrian explosion, a community of seaweeds and worm-like animals lived in a quiet deep-water niche near what is now Lantian, a small village in south China.

Then they simply died, leaving some 3,000 nearly pristine fossils preserved between beds of black shale deposited in oxygen-free and unbreathable waters.

Scientists from the Chinese Academy of Sciences, Virginia Tech in the United States and Northwest University in Xi'an, China report the discovery of the fossils in the Feb. 17 issue of the journal Nature.

In addition to ancient versions of algae and worms, the Lantian biota--named for its location--included macrofossils with complex and puzzling structures.

In all, scientists have identified some 15 species at the site.

The fossils suggest that structural diversification of macroscopic eukaryotes--the earliest versions of organisms with complex cell structures--may have occurred only tens of millions of years after the event that ended 635 million years ago.

Snowball Earth proposes that the Earth's surface became almost, or completely, frozen at least once during the planet's history.

The presence of macroscopic eukaryotes in the highly organic-rich black shale suggests that, despite the overall oxygen-free conditions, brief of the oceans did come and go, according to H. Richard Lane, program director in the National Science Foundation (NSF)'s Division of Earth Sciences, which funded the research.

"So there are two questions," says Shuhai Xiao, a geobiologist at Virginia Tech. "Why did this community evolve when, and where, it did?

"It is clearly different in terms of the number of species compared to biota preserved in older rocks. There are more species here, and they are more complex and larger than what evolved before."

The rocks were formed shortly after the largest ice age ever, says Xiao, when much of the global ocean was frozen.

By 635 million years ago, the snowball Earth event ended and the oceans were clear of ice. Perhaps, Xiao says, "that prepared the ground for the evolution of complex eukaryotes."

The team examined the black shale rocks because, although they were laid down in less than optimal waters for oxygen-dependent organisms, "they are known to be able to preserve fossils very well," says Shuhai.

"In most cases, dead organisms were washed in and preserved in black shales. In this case, we discovered fossils that were preserved in pristine condition--some still rooted--where they had lived."

This seaweed holdfast is a 600 million-year-old fossil from the Lantian Formation in China. Credit: Zhe Chen and Xunlai Yuan

The conclusion that the environment would have been poisonous is derived from geochemical data, "but the bedding surfaces where these fossils were found represent moments of geologic time during which oxygen was available and conditions were favorable," says Xiao.

"They are very brief moments to a geologist, but long enough for the oxygen-demanding organisms to colonize the Lantian basin and capture the rare opportunities."

The research team suggests that the Lantian basin was largely without oxygen, but was punctuated by brief oxic episodes that were populated by complex new life forms.

Those life forms were subsequently killed and preserved when the oxygen disappeared.

"Such brief intervals need high-resolution sampling for geochemical analysis to capture the dynamic and complex nature of oxygen history in the Ediacaran Period," says lead paper author Xunlai Yuan. The Ediacaran Period is the last geological period immediately preceding the Cambrian Period.

Proving that hypothesis awaits further study.

The rocks in the study region are deposited in layered beds. The nature of the rock changes subtly, and there are finer and finer layers that can be recognized within each bed.

"We will need to sample each layer to see whether there is any difference in oxygen contents between layers with fossils and those without," says co-author Chuanming Zhou.

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User comments : 14

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Johannes414
1.3 / 5 (15) Feb 23, 2011
Scientists have no clue. Their theories fail to make sense of the sudden advent of life forms. Abiogenesis and evolution were invented by the ancient Greeks who believed in an eternal universe. Fossils need rapid burial in order to form, so long ages wont do a thing.
kaasinees
3.7 / 5 (6) Feb 23, 2011
You do realize research like this is to make people like you shut up?

Well its one of the many reasons.
Johannes414
1.6 / 5 (7) Feb 23, 2011
Heb je het artikel wel gelezen makker? Niets dan vragen die weer andere vragen oproepen. De wetenschap heeft geen idee hoe leven is ontstaan.
omatumr
1.4 / 5 (9) Feb 23, 2011
Life and nuclear particles evolved on opposite sides of the glowing, opaque sphere that we call the "photosphere."

The photosphere is not the surface of the Sun, but the photon-emitting layer of waste products (91% H and 9 % He) from the neutron star at the Sun's core:

arxiv.org/pdf/1102.1499v1

With kind regards,
Oliver K. Manuel
Former NASA Principal
Investigator for Apollo
kaasinees
3 / 5 (4) Feb 23, 2011
Heb je het artikel wel gelezen makker? Niets dan vragen die weer andere vragen oproepen. De wetenschap heeft geen idee hoe leven is ontstaan.


Misschien JOUW wetenschap.
Johannes414
1 / 5 (5) Feb 23, 2011
Wat voor wetenschappelijke achtergrond heb je?
FrankHerbert
1 / 5 (4) Feb 23, 2011
Waarom bent u die spreken in Nederlands u stomme homosexual? En de wetenschap heeft overvloed van ideeën over hoe het leven zich u de eter van idiootfaecaliën heeft voorgedaan.
GSwift7
5 / 5 (1) Feb 24, 2011
Shale, and especially dark/black shale, is thought to form in still water. A glacial lake might be a good place for shale to form, for example. Such a still water column would be anoxic by default, as the oxygen would be consumed by chemical reactions and biological processes fairly quickly. If there were periods when the water column got stirred up, maybe by a few decades of melt-water inflow, it would be re-oxygenated allowing oxygen breathing organisms to survive. Then if the stirring ceased for a few years, they would suffocate. What they are observing above may not indicate a general atmospheric trend in oxygen levels. It could just be periods of relative change in the water body.

The life they see in the fossils could be spread all over the place, and thriving in places where the water isn't so stagnant. Less stagnant water wouldn't make shale and therefor wouldn't preserve fossils as well, so evidence should be hard to find.
BYTEMAN
1 / 5 (4) Feb 25, 2011
GOOGLE "FAKE CHINESE FOSSILS" AND YOU WON'T HAVE ANYTHING TO ARGUE ABOUT - IN ANY LANGUAGE !!
Ethelred
5 / 5 (2) Feb 25, 2011
GOOGLE "FAKE CHINESE FOSSILS"
Google fake dinosaur footprints and human footprints and you will be confronted with reality.

Ethelred
BYTEMAN
1 / 5 (2) Mar 05, 2011
I'VE "GOOGLED" FAKE DINOSAUR FOOTPRINTS AND THE GENERAL CONSENSUS OF OPINION IS THAT THEY EXIST. MANY FOSSILS FROM THE LIAONING REGION OF CHINA ARE KNOWN TO BE FAKED. WHICH ARGUMENT DO YOU WANT TO ARGUE ABOUT - CHINESE FOSSILS OR DINOSAUR FOOTPRINTS ??!!
Ethelred
5 / 5 (1) Mar 06, 2011
I'VE "GOOGLED" FAKE DINOSAUR FOOTPRINTS AND THE GENERAL CONSENSUS OF OPINION IS THAT THEY EXIST. MANY FOSSILS FROM THE LIAONING REGION OF CHINA ARE KNOWN TO BE FAKED.
Would you please PRETTY PLEASE google CAPS LOCK KEY and when you find it TURN IT OFF.

The fake dinosaur footprints are the the Bible Belt. It isn't the dinosaur footprints that were faked, it was the alleged human foot prints. Those were faked.

DO YOU WANT TO ARGUE ABOUT - CHINESE FOSSILS OR DINOSAUR FOOTPRINTS ??!!
Do you have a point? There a few fakes that have come out of China, They were for sale not for science.

Try actually communicating. Say what you mean. Engage in discussions. Or quit wasting bits.

Ethelred
BYTEMAN
1 / 5 (2) Mar 06, 2011
DON'T BE SO SERIOUS! I ALWAYS USE CAPITALS TO IDENTIFY ME FROM OTHER BYTEMEN! HOWEVER THE REASON FOR MY INITIAL POST WAS TO ALERT PEOPLE TO THE FOLLY OF BELIEVING EVERY THING THAT IS SCIENTIFICALLY REPORTED. I AM INTERESTED IN BIRDS AND KEEP AN INDOOR AVIARY. I RESEARCHED FOSSIL BIRDS AND BLINDLY TOOK EVERYTHING IN. SO WAS NATIONAL GEOGRAPHIC WHO PUBLISHED AN ARTICLE ON THESE FINDS. I HAVE NO FIXED OPINION ON EVOLUTION.
Ethelred
5 / 5 (2) Mar 08, 2011
DON'T BE SO SERIOUS!
Don't be so annoying Joker.

I ALWAYS USE CAPITALS TO IDENTIFY ME FROM OTHER BYTEMEN!
Quit using a generic handle and you won't have that problem/excuse for poor manners.

HOWEVER THE REASON FOR MY INITIAL POST WAS TO ALERT PEOPLE TO THE FOLLY OF BELIEVING EVERY THING THAT IS SCIENTIFICALLY REPORTED.
Are you really that unaware that you think no else is ever skeptical? In any case there is no reason whatsoever to think these are fake fossils. The fakes you referred to were for selling to tourists and collectors not to science.

I RESEARCHED FOSSIL BIRDS AND BLINDLY TOOK EVERYTHING IN.
Then you were an idiot. Goes with the sort of mind that insists on being rude with all caps posts.

I HAVE NO FIXED OPINION ON EVOLUTION.
That is a claim half the Creationists here make.

Learn how to post
Do get a clue
There are no other bytemen
Thank Turing for that
You are not the only skeptic

Sing this to don't drink and drive

Ethelred