An artist’s rendering of a rainbowfish attempting to sneak up on a frog floating on the surface of a pond while another rainbowfish regurgitates part of a recent meal of frogs and of a salamander. The bowfish is the suspected predator of a 150-million-year-old vomit fossil discovered in southeastern Utah. (Brian Engh via Utah State Parks Division)
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VERNAL – A fossil recently discovered in southeastern Utah appears to show the type of prey that predators feasted on in the days of the dinosaurs and when the area wasn’t quite the desert it is today today.
Utah paleontologists have discovered a pile of amphibian bones that they say appear to have been vomited up by some sort 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.
Their findings were published in the journal Palaios last month.
“This fossil gives us rare insight into animal interactions in ancient ecosystems,” John Foster, 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 scouring the Morrison Formation, a famous paleontological site known for its Late Jurassic fossils, which spans from around 148 million years ago to 155 million years ago. It’s best known for its dinosaur bones, but it’s also where scientists have found all sorts of other animals, like fish, salamanders and frogs.
The southeast Utah section of the formation features mostly prehistoric plants like ginkgos, ferns, and conifers; however, paleontologists have also found amphibians and bowfish there. These finds explain why they believe the area once housed a pond or small lake.
But during a recent investigation, the team discovered a strangely arranged fossil. It was a group of bones that included “elements” of at least one small frog or tadpole and would be the “smallest salamander specimen reported from the formation,” the researchers wrote in the study. Some of these bones were only 0.12 inches long, which is among the smallest sets of bones in the formation.
They added that the chemical and bone structure of the fossil indicated that it was regurgitation, which is a fossilized form of vomit. The team noted that this is the first such find in the Morrison Formation and also in the Jurassic period of North America.
What is still unclear 150 million years later is what killed the species in regurgitation. Foster points out that previous research places bowfish in the area at the time, which he considers the “current best match” for the predator behind the fossil. Scientists have discovered species of fish, salamanders and frogs in the Morrison Formation for over a century.
“While we can’t rule out other predators, an arc fin is our current suspect, so to speak,” he said, explaining that fish – and other animals – sometimes regurgitate their meals. recent when they are pursued or want to distract a potential predator.
“There were three animals that we still have today, interacting in ways also known today between these animals – prey eaten by predators and predators possibly hunted by other predators,” he said. he adds. “That in itself shows how similar some ancient ecosystems were to places on Earth today.”
The discovery is the team’s most recent in the area. Two of the study’s three co-authors also help uncover a huge 151 million-year-old water bug, which led to a paper published in 2020.
James Kirkland, the state paleontologist who co-authored both studies, said paleontologists plan to continue to search for the site where the prehistoric vomit was discovered to see if they can find more evidence of the ecosystem. past of the region.
“I was so excited to have found this site because Late Jurassic plant localities are so rare,” he said in a statement. “We must now carefully dissect the site in search of smaller wonders among the foliage.”