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Precamrbian Embryos



Very interesting pictures. Had no idea something like this could be
preserved.

http://www.unirel.vt.edu/vtnews/story.php?itemno=408

Blacksburg, Va., November 3, 2004 -- In 1998, Shuhai Xiao and colleagues
reported finding thousands of 600-million-year-old embryo microfossils in
the Neoproterozoic Doushantuo Formation, a fossil site near Weng''an,
South China (Xiao, S., Zhang, Y., and Knoll, A.H., 1998,
"Three-dimensional preservation of algae and animal embryos in a
Neoproterozoic phosphorite," Nature, v. 391). Within the egg cases they
examined at that time, they discovered animals in the first stages of
development  from a single cell to only a few dozen cells. "The cellular
preservation is amazing," said Xiao, assistant professor of geosciences in
the College of Science at Virginia Tech.

But what kind of adult would these ancient embryos have hatched into?

In 2000, Xiao's team reported the discovery of a coral-like animal that
might be a candidate for parenthood (Xiao, S., Yuan, X., and Knoll, A.H.,
2000, "Eumetazoan fossils in terminal Proterozoic phosphorites?"
Proceedings of the National Academy of Sciences, USA, v. 97). "It was
tubular, not spherical. But in some of the best specimens, we could see
that the tube branches and has cross-walls," Xiao said. "But can it be
linked to the embryos?"

Upon examination of more embryos collected from the original site, Xiao's
research team has discovered some embryos that may be at the hatching
stage. He will report on this latest finding at the Geological Society of
America meeting in Denver, Nov. 7-10.

"Looking now at these egg cases, we can see clockwise spiral grooves, as
if a knife sliced the egg open," Xiao said. "The embryo was beginning to
hatch. When we removed the egg case, we found that the post blastula but
pre-hatching embryo at this stage is beginning to transform into a spiral
animal. Each such animal had three clockwise spires. After hatching, the
spiral organism began to uncoil slightly," Xiao said.

"They look as if they can unwind to a tube structure. We are looking for
more evidence, but if that is true, it might link the embryo fossils to
the tubular coral-like animal."
...


Pictures at

 http://www.geol.vt.edu/paleo/Xiao/#Research