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Prehistoric comb jelly fossil found in Utah at least 500M years old, researchers say

An illustration of what two prehistoric jelly combs looked like about 500 million years ago. The new species was discovered from fossils preserved in central Utah.

An illustration of what two prehistoric jelly combs looked like about 500 million years ago. The new species was discovered from fossils preserved in central Utah. (Holly Sullivan via Harvard University)

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SALT LAKE CITY — A set of comb jelly fossils believed to be at least 500 million years old found in central Utah may provide a better understanding of how the nervous system evolved in prehistoric creatures, international researchers wrote in a study published this month.

The team of researchers — from the University of Oxford in the United Kingdom, Harvard University and Yale University — studied the fossils of two previously unknown ctenophore species discovered in the Marjum Formation within the House Range in Millard County. They wrote in a study published in iScience on Aug. 4 that both were from the Cambrian Period, which ranges between about 485 and 541 million years ago, and are the first ctenophore fossils ever found in the United States.

Ctenophores are described as predatory gelatinous macroinvertebrate sea creatures. The Utah fossils aren't as old as similar ones previously discovered in Canada and China, but were preserved in good enough conditions over hundreds of millions of years that the researchers were able to detect pieces of the nervous system in at least one of the fossil species, according to study.

The researchers said they found the pieces of the nervous system in a new species called "Ctenorhabdotus campanelliformis." The prehistoric species had a small bell-shaped body and up to 24 ctenes — called combs — with a "wavy mouth opening," according to study. That's compared to upwards of eight comb rows found in current living jellies.

But the team seemed more excited about finding the preserved pieces of its nervous system. They discovered long nerves that connected with a ring around the mouth of the species.

"This was quite an unexpected finding, as only one species, Euplokamis, of comb jellies today has comparable long nerves. Most modern comb jellies have a diffuse nervous net, and not well-defined long nerves," said Javier Ortega-Hernandez, a professor in the Department of Organismic and Evolutionary Biology at Harvard University and a co-author of the study, in a statement.

They called the second species, discovered in the same area, "Thalassostaphylos elegans." It had about 16 comb rows and was a bit rounder than the other species discovered. The species didn't have its nervous system attached but had other pieces that indicated changes in prehistoric ctenophores all the way back in the mid-Cambrian Period, Ortega-Hernandez added. Still, both had more complex nervous systems than current living species of comb jellies.

"This discovery means that there has a been a secondary simplification of comb jellies during their evolution, first losing the rigid skeleton and then the discrete nerves observed in the fossils," said Luke Parry, a junior research fellow inside University of Oxford's Department of Earth Sciences, and the study's lead author in a statement.

He added the type of insight is something that researchers couldn't have learned by simply studying just living comb jellies and their ancestral fossil counterparts alone.

A part of the reason the fossils were kept in such extraordinary condition is how they were buried in Utah. The area is known for well-kept marine fossils and the two comb jelly fossils were found in films of organic carbon, which helped preserve the internal organs for millions and millions of years, according to the research team.

Philip Gensler, the acting regional paleontologist for the Bureau of Land Management, said the location is home to over 100 species of invertebrate fossils from the Cambrian Period. The fossils were sent to the Natural History Museum of Utah after the researchers conducted their study to be held there for museum curation.

The fossils are just the latest in what has been an interesting year of prehistoric discoveries in or near Utah. In February, Utah paleontologists studying a Utahraptor megablock from Grand County announced that it contained more dinosaur fossils than originally believed.

BLM paleontologists revealed in April they had stumbled across a mass tyrannosaurs burial site in Kane County, which resulted in confirmation that the species hunted in packs. A month later, a University of Utah geologist published a study on 58 million-year-old fossilized tracks in Wyoming created by an extinct mammal similar to a hippopotamus.

And earlier this summer, a 152-million-year-old log fossil was unearthed in eastern Utah and brought to the Utah Field House of Natural History State Park Museum in Vernal.

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Carter Williams is an award-winning reporter who covers general news, outdoors, history and sports for He previously worked for the Deseret News. He is a Utah transplant by the way of Rochester, New York.


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