Featured Research

from universities, journals, and other organizations

Oldest Animal Fossils May Have Been Bacteria

Date:
December 21, 2006
Source:
University of Southern California
Summary:
The oldest-known animal eggs and embryos, whose first pictures made the cover of Nature in 1998, were so small they looked like bugs -- which, it now appears, they may have been. This week, a study in the same prestigious journal presents evidence for reinterpreting the 600 million-year-old fossils from the Precambrian era as giant bacteria.

Lead author Jake Bailey, a graduate student in earth sciences at USC College.
Credit: Photo Lauren Walser

The oldest-known animal eggs and embryos, whose first pictures made the cover of Nature in 1998, were so small they looked like bugs -- which, it now appears, they may have been.

This week, a study in the same prestigious journal presents evidence for reinterpreting the 600 million-year-old fossils from the Precambrian era as giant bacteria.

The discovery "complicates our understanding of microfossils thought to be the oldest animals," said lead author Jake Bailey, a graduate student in earth sciences at the University of Southern California.

Bailey made his discovery by combining two separate findings about Thiomargarita, the world's largest known living bacterium.

In 2005, Thiomargarita discoverer Heide Schulz, from the University of Hannover in Germany, showed that the bacterium promotes deposition of a mineral known as phosphorite.

The fossils identified as eggs and embryos in 1998 came from southern China's Doushantuo Formation, which is rich in phosphorite.

The source for the rare mineral was unknown. Bailey wondered if an ancient relative of Thiomargarita might have been involved.

"The idea is that these bacteria were causing these phosphorite deposits to form," Bailey said.

Also in 2005, University of Georgia marine biologists Samantha Joye and Karen Kalanetra, who are co-authors on Bailey's study, found that Thiomargarita can multiply by reductive cell division, a process rare among bacteria but typical of animal embryos.

Bailey knew that the fossils had been identified as embryos in part because they showed evidence of reductive cell division. Then he thought again about the phosphorite deposits.

"When I put those two pieces together, I said ... perhaps they're not animal embryos at all."

Bailey and his co-authors compared the size and geometrical properties of the Doshuanto fossils and modern Thiomargarita bacteria -- they were nearly identical.

Coupled with the presence of phosphorite, the result pointed strongly to ancient Thiomargarita activity.

"I was shocked that there was this other option out there," Bailey said.

The finding also solved a longstanding puzzle. Proponents of the animal theory had struggled to explain how eggs and embryos could be preserved, as neither fossilizes easily.

These bacteria, on the other hand, make better fossil candidates. And by depositing phosphorite, Thiomargarita even supplies its own rock matrix, or fossil bed.

The Nature study's authors, which include Bailey's adviser Frank Corsetti and USC biology graduate student Beverly Flood, were careful not to rule out the existence of animal fossils from the same geological era. The Doushantuo Formation contains the fossils of many species, some of which have been identified as animals.

While calling the evidence for animal life in the Doushantuo "controversial," Bailey noted that other fossils in the formation "bear little resemblance to Thiomargarita.

"Our paper offers an alternative interpretation of the most abundant microfossils in the Doushantuo Formation," he added. "The structures that we discuss were the first Doushantuo fossils to be interpreted as embryos, and they've been widely accepted as such."

Regardless of the evidence for animal life in the Doushantuo, Bailey's study elevates Thiomargarita to the role of Great Preserver, since without its mineral contribution the other organisms might never have fossilized.

The study appears in the Dec. 20 issue of Nature. Funding for the group's research came from the National Science Foundation, NASA, the U.S. Department of Energy and the National Oceanic and Atmospheric Administration.


Story Source:

The above story is based on materials provided by University of Southern California. Note: Materials may be edited for content and length.


Cite This Page:

University of Southern California. "Oldest Animal Fossils May Have Been Bacteria." ScienceDaily. ScienceDaily, 21 December 2006. <www.sciencedaily.com/releases/2006/12/061220143854.htm>.
University of Southern California. (2006, December 21). Oldest Animal Fossils May Have Been Bacteria. ScienceDaily. Retrieved August 28, 2014 from www.sciencedaily.com/releases/2006/12/061220143854.htm
University of Southern California. "Oldest Animal Fossils May Have Been Bacteria." ScienceDaily. www.sciencedaily.com/releases/2006/12/061220143854.htm (accessed August 28, 2014).

Share This




More Fossils & Ruins News

Thursday, August 28, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

40,000-Year-Old Mammoth Skeleton Found On Texas Farm

40,000-Year-Old Mammoth Skeleton Found On Texas Farm

Newsy (Aug. 26, 2014) A mammoth skeleton was discovered in a gravel pit on Wayne McEwen's Texas farm back in May. It's now being donated to a museum. Video provided by Newsy
Powered by NewsLook.com
Pawn Shop Buys Lincoln Signature For $50, Worth $50,000

Pawn Shop Buys Lincoln Signature For $50, Worth $50,000

Newsy (Aug. 25, 2014) The signature is one of a couple Lincoln autographs that have popped up recently. Video provided by Newsy
Powered by NewsLook.com
Neanderthals Probably Died Out Earlier Than We Thought

Neanderthals Probably Died Out Earlier Than We Thought

Newsy (Aug. 21, 2014) A new study is packed with interesting Neanderthal-related findings, including a "definitive answer" to when they went extinct. Video provided by Newsy
Powered by NewsLook.com
Disquieting Times for Malaysia's 'fish Listeners'

Disquieting Times for Malaysia's 'fish Listeners'

AFP (Aug. 19, 2014) Malaysia's last "fish listeners" -- practitioners of a dying local art of listening underwater to locate their quarry -- try to keep the ancient technique alive in the face of industrial trawling and the depletion of stocks. Duration: 02:29 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins