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Multicellular fossils may be world's oldest
Fossils found in Gabon suggest
complex organisms lived as far back as 2.1 billion years
[image: Gabonese Fossils]
Paleontologists used X-ray tomography to virtually reconstruct the outer
form, left, and inner structure of the fossil specimens.
- [image: Map: Oldest known multicellular fossil
Oldest known multicellular fossil
An international team of paleontologists has uncovered the earliest
multicellular fossils, pushing back the fossil record for such life
2.1 billion years ago and suggesting that they lived 200 million years
earlier than scientists had thought.
Since most fossils in that period were microscopic and single-celled,
finding fossils that stretched as long as 4.75 inches was "like ordering
hors d'oeuvre and some gigantic thick-crust pizza turning up," said
Donoghue, a paleontologist at the University of Bristol, who co-wrote a
commentary on the finding. The report detailing the fossils, along with
commentary, was published online Wednesday in the journal
The organisms, which don't resemble modern-day living things, existed
Earth's atmosphere would have been uninhabitable for today's plants and
Their fossils provide "the first record of that fundamental threshold in
organismal complexity being surpassed," Donoghue said. "To put it into
context, the godfather of evolutionary biology, John Maynard Smith,
identified eight major events in evolutionary history; achieving
multicellularity was one of these."
"I was astonished.... It's not the sort of thing you expect to see in
of that age," Donoghue said.
Paleontologist Abderrazak El Albani, the report's lead author, said the
macroscopic fossils, which are visible to the naked eye, turned up at a
point during the Paleoproterozoic era when life was thought to exist on
a purely microbial level.
Learning about how and under what conditions that turning point was
it has happened at least 17 times in lineages that are still living,
Donoghue said could reveal much about how life developed.
The finding also dovetails with theories describing what Earth's
must have been like at the time, illuminating how the changing
may have played a role in the development of life.
About 2.4 billion years ago, scientists say, oxygen began to build up
dramatically in the environment. Though the element would have amounted
to only a fraction of current levels, it may have been sufficient to
allow some creatures to begin developing into multicellular organisms,
the researchers theorize.
Given that the record for such ancient forms of multicellular life is
at best, Donoghue said, "we're certainly hungry for fossils in those
intervals of our history."
Study coauthor Stefan Bengtson, a paleozoologist with the Swedish Museum
of Natural History, pointed out that multicellularity was a key
life on Earth because "once you start building things with smaller
you can start building new structures, like a Lego game."
But there's still a long evolutionary road between these creatures and
whose genetics were complex enough to develop different tissues and
within a single body, Bengtson said.
El Albani, of the University of Poitiers in France, said his team had
looking to study the sediments at the black shale formations in Gabon
they came across the fossils.
They weren't much to look at: lumpy and doughy-looking, though hard, of
course. But a scan using X-ray tomography revealed complex organization
"It's spectacular.... It's really something," El Albani said of the
The team also had to prove that the structures had been organic in
The fossils were found to contain tiny grains of pyrite, or fool's gold.
Such grains would have been created by sulfur-breathing bacteria
away at organic matter, in this case the soon-to-be fossils' dead
the scientists said.
El Albani said the next step would be to examine the fossils to learn
about how they lived and what their surroundings were like.
"I want to understand if this organism is moving or not; I want to
understand the paleological ecosystem," he said.