Fossils bare oldest being
26/8/2005 8:16
Tiny fossils spotted in southwest China's Yunnan-Guizhou Plateau
indicate the earliest complex animal species were possibly born in China and
appeared on the surface of the Earth about 580 million years ago, much earlier
than had been thought.
The latest issue of Scientific American this month
carries an article about the significance of the tiny, button-shaped organism
dating back 580 million years ago, which was believed to be the oldest animal
species with symmetrical structure.
Unearthed from Chinese phosphate mines,
these species provide the most ancient evidence of animal species complex enough
to have a symmetrical two-sided body plan, just like flies, fish and humans in
the modern world, instead of a round or radial one.
"They date back to the
time prior to the Cambrian Period at least 40 million years ago, when the
fossils recorded a big bang of life," said Chen Junyuan, a paleontologist with
the Nanjing Institute of Geology and Paleontology in China.
"The delicately
preserved fossils indicated the dawn for the world of diversified living
species," Chen said. Before the Cambrian Period 550 million years ago, most life
on Earth took the form of bacteria and single-celled species.
The exact
timing of the emergence of bilateral animal species, which have defined front,
rear, left and right body surfaces, has long been a topic of debate in the
scientific community.
Working along with a team of experts from overseas,
Chen named the new living species Vernanimalcula guizhouena, meaning "small
spring animal from Guizhou" - a nod by the team to the "spring" following the
so-called "Snowball Earth" period that ended roughly 600 million years ago when
it was theorized that most of the planet was entombed in ice.
Chen and his
peers described 10 bilateral fossils they spotted and collected from the
Doushantuo Formation in China, which constitutes a phosphorite rock formation
that developed in a shallow sea between 580 to 600 million years ago. The oval
Vernanimalcula guizhouena was about 0.2 millimeters.
These soft bodies were
kept intact due to the phosphate, which quickly worked its way into the cellular
structures.
Xinhua
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