Navigation Links
Oldest fossils of large seaweeds, worm-like animals tell story of ancient oxygen
Date:2/23/2011

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 Snowball Earth 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 oxygenation 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 seaweeds still rooted--where they had lived."

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.


'/>"/>

Contact: Cheryl Dybas
cdybas@nsf.gov
703-292-7734
National Science Foundation
Source:Eurekalert  

Related biology news :

1. Researchers uncover worlds oldest fossil impression of a flying insect
2. 4,000-year-old coral beds among worlds oldest living things, prof says
3. Kent State University Professor C. Owen Lovejoy helps unveil oldest hominid skeleton
4. Ardi displaces Lucy as oldest hominid skeleton
5. Dinosaur-chewing mammals leave behind oldest known tooth marks
6. Oldest Earth mantle reservoir discovered
7. Scientists discover oldest evidence of human stone tool use and meat-eating
8. UNH researcher helps identify key reproductive hormone in oldest vertebrate
9. Oldest evidence of dinosaurs found in Polish footprints
10. VTT to study one of worlds oldest beers
11. Oldest species of a marine mollusc discovered
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Oldest fossils of large seaweeds, worm-like animals tell story of ancient oxygen
(Date:5/12/2016)... DALLAS , May 12, 2016 ... has just published the overview results from the Q1 ... of the recent wave was consumers, receptivity to a ... wearables data with a health insurance company. ... choose to share," says Michael LaColla , CEO ...
(Date:4/26/2016)... LONDON , April 26, 2016 /PRNewswire/ ... Systems, a product subsidiary of Infosys (NYSE: ... partnership to integrate the Onegini mobile security platform ... http://photos.prnewswire.com/prnh/20151104/283829LOGO ) The integration ... security to access and transact across channels. Using ...
(Date:4/14/2016)... TEL AVIV, Israel , April 14, 2016 /PRNewswire/ ... in Behavioral Authentication and Malware Detection, today announced the ... has already assumed the new role. Goldwerger,s ... for BioCatch, on the heels of the deployment of ... In addition, BioCatch,s behavioral biometric technology, which discerns unique ...
Breaking Biology News(10 mins):
(Date:6/23/2016)... (PRWEB) , ... June 23, 2016 , ... ... today announced the launch of the Supplyframe Design Lab . Located in ... to explore the future of how hardware projects are designed, built and brought ...
(Date:6/23/2016)... 23, 2016 Apellis Pharmaceuticals, Inc. today ... trials of its complement C3 inhibitor, APL-2. The ... ascending dose studies designed to assess the safety, ... injection in healthy adult volunteers. Forty ... a single dose (ranging from 45 to 1,440mg) ...
(Date:6/23/2016)... YORK , June 23, 2016 ... trading session at 4,833.32, down 0.22%; the Dow Jones Industrial ... S&P 500 closed at 2,085.45, down 0.17%. Stock-Callers.com has initiated ... INFI ), Nektar Therapeutics (NASDAQ: NKTR ), ... Therapeutics Inc. (NASDAQ: BIND ). Learn more about ...
(Date:6/23/2016)... ... June 23, 2016 , ... ... of intelligent tools designed, tuned and optimized exclusively for Okuma CNC machining centers ... The result of a collaboration among several companies with expertise in toolholding, cutting ...
Breaking Biology Technology: