Uncovering Utah's Deep Sea Mysteries

500 million years ago, there were jellyfish living in western Utah. Hard to believe, isn't it? To start with, western Utah is terrible jellyfish habitat - there are no oceans for hundreds of miles! If you went there today, you'd have a hard time finding anything that swims at all, much less a deep-water, ocean-loving creature like a jellyfish. On top of that, 500 million years is a very long time - how do we know what was there?

These are some good questions, and luckily there are good answers. We know that jellyfish were there because two geologists from the University of Utah found them. Or, to be precise, they found fossilized traces of the creatures' remains. Researchers Richard D. Jarrard and Susan Halgedahl spent time cracking open rocks at the fossil site west of Delta, where other ancient animal traces had been seen before. They were pretty excited by what they found - the remains of four different species of ancient jellyfish.

"It's hard to imagine anything more difficult to create a fossil from than a jellyfish that's less than half an inch in size...They just don't have any hard parts at all," Jarrard told the Deseret Morning News. Most of the time, their soft bodies decay and become part of the environment around them, even in areas where the conditions are right for preserving fossil traces of harder material like bones or shells. But not this time.

Why not? And how were there jellyfish in western Utah at all? While today it's a desert - dry as a bone - for hundreds of millions of years, starting around 570 million B.C., western Utah was under the ocean. California and Nevada weren't around, and the west coast of North America ran right through our now-desert state. In the deep water over the present-day fossil site, the jellyfish swam, ate, bred, and died. And for a while during those hundreds of millions of watery years, the guck at the bottom of the western Utah ocean was just right for a jelly to float down and leave its mark. That ocean bottom became the Marjum formation of sedimentary rock, where the jellyfish fossils were found.


After finding the fossils, Jarred and Halgedahl sent them to experts at the University of Kansas, who determined that the fossils are related to modern jellyfish, are much older than any jellyfish fossils ever found before, and are also surprisingly sophisticated. That's exciting for scientists trying to work out the mystery of how life started on Earth, giving them important clues to life in the oceans way far back in time. Hurray for the jellies!


What might the landscape where you live have looked like 500 million years ago? How could you know?