Excerpted from http://www.washingtonpost.com/wp-srv/digest/tech1.htm
New Light on a Mysterious Epoch
By Kathy Sawyer
Washington Post Staff Writer
Thursday, February 5, 1998; Page A01
Scientists have unearthed what appear to be the first fossils of complex
animal ancestors dating back almost 600 million years, unexpectedly flinging
open a new window on a mysterious and crucial epoch in the history of life
on Earth.
Perhaps most stirring, the exquisitely preserved fossils include fragile
animal embryos no bigger than grains of sand, frozen forever in their
earliest stages of growth and revealed in three-dimensional precision down
to the level of individual cells, researchers reported yesterday. There are
also abundant marine algae (seaweed) and sponges ö the oldest known
representatives of any animal group alive today.
The discovery, which scientists hailed as one of the most important
evolutionary developments of this century, sent ripples of excitement
through the scientific community. Many paleontologists had been convinced
that such an ancient time, presumably populated with very small, squishy,
slithery creatures, could not have bequeathed modern science much of a
fossil record. Although they knew life must have existed in some form before
540 million years ago, researchers had found virtually no clear fossil
evidence of multicellular plant or animal life from that time period.
The new trove, found in a blanket of rock in southern China called the
Doushantuo Formation, dating back 570 million years (give or take 20 million
years), demonstrates dramatically that the "long and lightless" period known
as the Precambrian is no longer beyond the reach of direct scientific
investigation, researchers said.
The complexity of the Doushantuo fossils suggests that multicellular life
originated much earlier than the 600 million year estimate some researchers
have proposed. They "provide the first direct geological evidence in support
of the hypothesis that the main [groups of multicelled organisms]
diversified before the emergence of a conspicuous animal fossil record,"
according to a research team led by Shuhai Xiao of Harvard; with Andrew H.
Knoll, also of Harvard; and Yun Zhang of Beijing University.
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