500 my Old Jellyfish Impressions Found

[Richard W Travsky <rtravsky@uwyo.edu>]

Really cool picture accompanies the text


http://www.nytimes.com/2002/01/26/science/26FOSS.html

PASADENA, Calif., Jan. 25 Thousands of fossilized impressions of
jellyfish, some up to three feet in diameter, have been discovered in a
Wisconsin quarry, in what scientists say is one of the largest finds of
its kind in the world.

About 510 million years ago, the jellyfish were washed up in a small
lagoon, stranded by a freakish tide or storm, and buried by sand just
hours later.

"Preservation of a soft-bodied organism is incredibly rare, but a whole
deposit of them is like finding your own vein of gold," said James
Hagadorn, a scientist at the California Institute of Technology here and
co-author of an article reporting the discovery in February's issue of the
journal Geology.
...
A fossil dealer, Dan Damrow, a co-author of the Geology article,
discovered the jellyfish about four years ago in a quarry in Mosinee,
Wis., about 200 miles northwest of Milwaukee.  In the quarry, beds of
sandstone lie stacked horizontally in neat layers, perfect for flagstone
and other commercial uses.
...
Mr. Hagadorn said they found fossilized jellyfish in seven layers in the
quarry, encased in about 12 vertical feet of rock representing a span of
time of up to one million years.

The layers of rock also record the delicate ripples that striped the ocean
bottom in what were presumably shallow coastal waters.

Circular impressions mark where each jellyfish was washed ashore, probably
during a storm- enhanced high tide, Mr. Hagadorn said. Each fossil
typically includes a concave, circular shape that records the tiny moat
excavated by the pumping action of the bell- shaped jellyfish as it tried
to swim to deeper water.
...
The fossilized jellyfish appear similar in size and characteristics to
their modern brethren, but the specific species cannot be pinpointed.