Fossil record reveals elusive jellyfish more than 500 million years old

Oct 31, 2007
Fossil record reveals elusive jellyfish more than 500 million years old
This jellyfish is more than 500 million years old, the oldest jellyfish in the fossil record to date. Credit: University of Kansas

Using recently discovered “fossil snapshots” found in rocks more than 500 million years old, three University of Kansas researchers have described the oldest definitive jellyfish ever found.

In a paper to be published in PLoS ONE on October 31, the researchers describe four types of cnidarian fossils preserving traits that allow them to be related to modern orders and families of jellyfish. The specimens are about 200 million years older than the oldest previously discovered jellyfish fossils.

“The fossil record is full of circular shaped blobs, some of which are jellyfish,” said Paulyn Cartwright, KU assistant professor of ecology and evolutionary biology and one of the article’s authors. “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.”

The jellyfish left behind a film in fine sediment that resembles a picture of the animal. Most jellyfish do not leave such a clear impression behind because they are often preserved in coarse sand.

Cartwright, Bruce Lieberman, KU professor of geology and senior curator of invertebrate paleontology at the KU Natural History Museum, and Jonathan Hendricks, postdoctoral researcher in geology at KU, collaborated on the article. Their research will be published October 31 in PLoS ONE, an online peer-reviewed journal by the Public Library of Science. Other researchers involved in the discoveries were Susan L. Halgedahl and Richard D. Jarrard, both of the University of Utah, Salt Lake City, Utah; Antonio C. Marques, University of San Paulo, San Paulo, Brazil; and Allen G. Collins, Smithsonian Institution, Washington, D.C.

Lieberman said the jellyfish the group describes, found in Utah, offer insights into the puzzle of rapid species diversification and development that occurred during the Cambrian radiation, a time when most animal groups appear in the fossil record, beginning roughly 540 million years ago. The fossil record reveals much less about the origin and early evolution of animals such as jellyfish than it does 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,” Lieberman said. “That means that we are still working to solve the evolutionary development of many soft-bodied animals.”

With the discovery of the four different types of jellyfish in the Cambrian, however, the researchers said that there is enough detail to assert that the types can be related to the modern orders and families of jellyfish. The specimens show the same complexity. That means that either the complexity of modern jellyfish developed rapidly roughly 500 million years ago, or that the group is even older and existed long before then.

Cartwright said the jellyfish described in the article are also unique because they push 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.

Source: Public Library of Science

Explore further: Archaeologists, tribe clash over Native remains

add to favorites email to friend print save as pdf

Related Stories

James Cameron, others to explore the real abyss

Mar 15, 2012

(AP) -- Earth's lost frontier is about to be explored firsthand after more than half a century. It's a mission to the deepest part of the ocean, so deep that the pressure is the equivalent of three SUVs sitting ...

High planetary tilt lowers odds for life?

Feb 06, 2012

Highly-tilted worlds would have extreme seasons, subjecting life to alternating periods of scorching and subzero temperatures. This could make the development of all but hardiest, simplest creatures a long ...

Catching space weather in the act

Feb 17, 2011

Close to the globe, Earth's magnetic field wraps around the planet like a gigantic spherical web, curving in to touch Earth at the poles. But this isn't true as you get further from the planet. As you move ...

Recommended for you

Bloody souvenir not from decapitated French king: DNA

4 hours ago

Two centuries after the French people beheaded King Louis XVI and dipped their handkerchiefs in his blood, DNA analysis has thrown new doubt on the authenticity of one such rag kept as a morbid souvenir.

Archaeologists, tribe clash over Native remains

Apr 23, 2014

Archaeologists and Native Americans are clashing over Indian remains and artifacts that were excavated during a construction project in the San Francisco Bay Area, but then reburied at an undisclosed location.

User comments : 0

More news stories

Genetic code of the deadly tsetse fly unraveled

Mining the genome of the disease-transmitting tsetse fly, researchers have revealed the genetic adaptions that allow it to have such unique biology and transmit disease to both humans and animals.

Ocean microbes display remarkable genetic diversity

The smallest, most abundant marine microbe, Prochlorococcus, is a photosynthetic bacteria species essential to the marine ecosystem. An estimated billion billion billion of the single-cell creatures live i ...