Washington, Oct 31 : Scientists have discovered what they claim is the oldest jellyfish fossils, dating back to more than 500 million years ago.

“This finding is unique because it pushes the known occurrence of definitive jellyfish back from 300 million to 505 million years, a huge jump, and show more detail than anything previously described that is younger,” said Paulyn Cartwright, assistant professor of ecology and evolutionary biology at Kansas University.

“The fossil record is full of circular shaped blobs, some of which are jellyfish. That's one of the reasons the fossils we describe are so interesting, because you can see a distinct bell-shape, tentacles, muscle scars and possibly even the gonads,” she said.

Co-researcher Bruce Lieberman said, this discovery offered insights into the puzzle of rapid species diversification and development that occurred during the Cambrian radiation, a time when most animal groups appeared in the fossil record 540 million years ago.

She said the fossil record revealed much less about the origin and early evolution of animals such as jellyfish than it did about 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. That means that we are still working to solve the evolutionary development of many soft-bodied animals,” said Lieberman.

The researchers said the discovery of the four different types of jellyfish in the Cambrian, provided further evidence that they could be related to the modern orders and families of jellyfish.

The specimens showed the same complexity, which meant that either the complexity of modern jellyfish developed rapidly roughly 500 million years ago, or that the group was even older and was in existence from an earlier date. (ANI)