150-million-year-old vomit found in Utah offers a “rare glimpse” into prehistoric ecosystems

An artist rendering of a bowfin fish attempting to sneak up on a frog floating at the surface of a pond while another bowfin regurgitates part of a recent meal of frogs and a salamander. The bowfin fish is the suspected predator of a 150 million-year-old vomit fossil discovered in southeast Utah.
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An artist’s rendering of a bowfin fish attempting to sneak up on a frog swimming on the surface of a pond while another bowfin part regurgitates part of a recent meal of frogs and a salamander. The bowfin fish is the putative predator of a 150-million-year-old vomit fossil discovered in southeastern Utah. (Brian Engh via Utah Division of State Parks)

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VERNAL — A recently discovered fossil in southeastern Utah appears to show the type of prey that predators fed on in the age of dinosaurs, before the region was quite the desert it is today.

Utah paleontologists discovered a pile of amphibian bones they say were spat out by some kind of predator. This prehistoric vomit is believed to be 150 million years old, according to paleontologists from the Utah Geological Survey, the Utah Division of State Parks, and the Flying Heritage & Combat Armor Museum in Washington.

Your insights were published in Palaios magazine last month.

“This fossil gives us a rare glimpse into how animals interacted in ancient ecosystems,” John Foster, the curator of the Utah Field House of Natural History State Park Museum and one of the study’s co-authors, said in a statement Tuesday.

The team discovered the fossil while combing through it Morrison Formation, a famous paleontological site known for its fossils from the Late Jurassic Age, ranging from about 148 million years to 155 million years ago. It’s best known for its dinosaur bones, but scientists have also found all sorts of other animals here, like fish, salamanders, and frogs.

The southeastern Utah section of the formation features mostly prehistoric plants such as ginkgoes, ferns, and conifers; However, paleontologists have also found amphibians and bowfin fish there. Based on these discoveries, they believe that either a pond or a small lake once existed in the region.

But during a recent investigation, the team uncovered an oddly arranged fossil. It was an assemblage of bones that contained “elements” of at least one small frog or tadpole and would be the “smallest reported salamander specimen from the formation,” the researchers wrote in the study. Some of these bones were only 0.12 inches long and are among the smallest bones within the formation.

They added that the fossil’s chemical and bone structure suggest it is regurgitate, a fossilized form of vomit. The team noted that this is the first find of its kind in the Morrison Formation and also in the North American Jurassic Period.

What is still not clear 150 million years later is what killed the species within the vomit. Foster points out that previous research at the time has brought bowfin fish to the region, which he considers the “current best match” for the predator behind the fossil. For well over a century, scientists have discovered species of fish, salamanders and frogs in the Morrison Formation.

“While we can’t rule out other predators, a bowfin is sort of our current suspect,” he said, explaining that fish — and other animals — sometimes regurgitate their last meals when they’re being pursued or trying to distract a potential predator.

“There were three animals that we still have today that interacted in ways that are also known among these animals today – prey eaten by predators and predators perhaps hunted by other predators,” he added . “That alone shows how similar some ancient ecosystems were to places on Earth today.”

The find is the team’s youngest in the region. Two of the three co-authors of the study also help Discover a giant water beetle 151 million years oldresulting in a paper published in 2020.

James Kirkland, the state paleontologist who co-authored both studies, said paleontologists plan to continue searching the site where the prehistoric vomit was discovered to see if they can find more evidence of the region’s past ecosystem .

“I was so excited to have found this place as plant sites are so rare in the Upper Jurassic,” he said in a statement. “We must now carefully dissect the site to look for other small marvels in the foliage.”


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Carter Williams is an award-winning reporter covering general news, nature, history and sports for He previously worked for the Deseret News. He’s a Utah transplant from Rochester, New York.

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