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Rare Ancient Jellyfish Remains found In Wisconsin

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Pretty Interesting.


Rare Fossilized Jellyfish Found



AP Photo




By ANDREW BRIDGES, AP Science Writer


PASADENA, Calif. (AP) - More than a half-billion years ago, thousands of jellyfish were washed up in a small lagoon, stranded by a freak tide or storm and buried by sand just hours later.


Fossilized impressions of those jellyfish, some up to 3 feet in diameter, have now been discovered in a Wisconsin quarry, in what scientists say is one of the largest finds of its kind in the world.


``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 and co-author of an article reporting the find in February's issue of the journal Geology.


The jellyfish, which have no durable body parts, were fossilized during the ancient Cambrian period, when the world's oceans exploded with a diversity of life. The creatures were apparently buried within hours after being stranded in a shallow lagoon some 510 million years ago.


Fossil dealer Dan Damrow, an article co-author, 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.


``These could have ended up as someone's bathroom floor or in their side garden,'' Hagadorn said.


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 1 million years.


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


``It gives you a kind of aura of standing in this instant in time,'' Damrow said. ``You're standing right on that beach just as it formed.''


Circular impressions mark where each jellyfish was washed ashore, probably during a storm-enhanced high tide, 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 attempted to swim to deeper water.


Surrounding that ring, a rim of higher rock represents the sand that washed against the dead or dying jellyfish in subsequent tides. Tiny piles in the center is likely sand ingested by the creature as it struggled, Hagadorn said.


The fossilized jellyfish appear similar in size and characteristics to their modern brethren, but the specific species cannot be pinpointed.


Beached jellyfish now fall prey to everything from birds to curious children. In the Cambrian period, however, there were few scavengers to disturb the creatures once they were grounded and buried, Hagadorn said. That, and the speed with which they were buried, accounted for their survival in the fossil record, he said.



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Here's the second part to the story.


Public release date: 24-Jan-2002

[ Print This Article | Close This Window ]


Contact: Ann Cairns



Geological Society of America


What are those big jellyfish fossils doing in Wisconsin?

It’s rare to find a jellyfish fossil--not having a skeleton, they easily decay. So why is an entire horde of them preserved in central Wisconsin?

Whitey Hagadorn from Caltech wondered the same thing after he learned about this exclusive deposit in the Upper Cambrian Mt. Simon-Wonewoc Sandstone in central Wisconsin. During the Cambrian, Wisconsin enjoyed a tropical environment and was covered by a shallow inland sea. Hagadorn and his colleagues present their hypothesis on how these jellyfish were preserved in the February issue of GEOLOGY.


They believe that the jellyfish were preserved because of a lack of erosion from sea water and wind, the lack of scavengers, and the lack of any significant sediment disturbance by other organisms after the jellyfish were stranded in the sand.


“It is very rare to discover a deposit which contains an entire stranding event of jellyfish,” Hagadorn said. “These jellyfish are not just large for the Cambrian, but are the largest jellyfish in the entire fossil record. What is also of interest is that they were among the largest two types of predators in the Cambrian.”


He thinks jellyfish may have been under-appreciated in previous studies of Cambrian ecosystems and that they were probably important predators in Cambrian food chains. He’s also documenting the deposit and trying to figure out how it was formed.


“We use fossils to assess the diversity and ecology of ancient communities,” Hagadorn said. “To date, most of our information about the trophic (food chain) structure of the Cambrian--when multicellular animals burst onto the scene--is based on animals with hard parts or on exceptional deposits which contain soft-bodied organisms. Despite the widespread study of rocks from this interval, very few jellyfish are known, and even fewer large pelagic (free-swimming) animals are known. So that means that when we analyze the trophic structure of the Cambrian--who ate whom, who ate them, and so forth, or when we analyze how abundant each type of organism was in each part of the food chain, we may have been inadvertently omitting a huge amount of information about all of the soft-bodied animals that were swimming around in the water column, munching on other organisms, but which were rarely fossilized. This deposit provides us a rare opportunity to study such animals."




By Kara LeBeau, GSA Staff Writer


Contact Information:

Whitey (James W.) Hagadorn

Division of Geological & Planetary Sciences

California Institute of Technology

Pasadena, CA 91125


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pretty incredible something as fragile as a jellyfish could leave its mark to be found over 1/2 billion years later. pretty amazing stuff.

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