This video from the USA says about itself:
I found these Fossils in a stream bed in TN, the largest is 3 ft across, smallest is 1 ft across. Anyone know what they are? I was told they were a type of jellyfish called a CENTATHORE.From LiveScience:
Oldest Known Jellyfish Fossils FoundSee also here.By Andrea Thompson, LiveScience Staff Writer
posted: 30 October 2007 05:31 pm ET
The oldest known fossils of jellyfish have been found in rocks in Utah that are more than 500 million years old, a new study reports.
The fossils are an unusual discovery because soft-bodied creatures, such as jellyfish, rarely survive in the fossil record, unlike animals with hard shells or bones.
“The fossil record is biased against soft-bodied life forms such as jellyfish, because they leave little behind when they die,” said study member Bruce Lieberman of the University of Kansas. …
The rich detail of the fossils allowed the team to compare the cnidarian (the phylum to which jellyfish, coral and sea anemones belong [see also here]) fossils to modern jellyfish. The comparison confirmed that the fossils were, in fact, jellyfish and pushed the earliest known occurrence of definitive jellyfish back from 300 million to 505 million years ago.
The fossils also offer insights into the rapid species diversification that occurred during the Cambrian radiation, which began around 540 million years ago and when most animal groups start to show up in the fossil record, Lieberman said.
The complexity of these early jellyfish seems to suggest that either the complexity of modern jellyfish developed rapidly about 500 million years ago, or that jellyfish are even older and developed long before that time.
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