UTAH (ABC4) – Paleontologists have found what appears to be the fossilized remains of vomited amphibians from the late Jurassic age in the rocks of the Morrison Formation in southeastern Utah. 

The Morrison Formation, an Upper Jurassic sedimentary rock in the western United States famous for its dinosaurs such as the Stegosaurus and the Brachiosaurus, contains a diverse variety of other animals. Many of these animals are familiar to the modern day such as frogs, salamanders, and fish. Although the area is dominated by plant fossils, these amphibians as well as bowfin fish have been found, representing remnants of a pond. 

The paleontologists say the arrangement of the bones in the fossil, the chemistry of the bones, and the mix of animals suggest the pile of bones was regurgitated by a predator. The amphibian bones are all tiny – some less than half an inch long – and include some of the smallest individual bones found in the Morrison Formation. Paleontologists have identified at least two individual frogs in the bones and possibly a tadpole. Salamander bones also appear in the fossil. 

So who was the likely source of the vomited remains?

“We can’t be sure,” said Utah Field House of Natural History State Park Museum Curator John Foster, co-author of the study. “But among the animals of interest here, the current best match, and the one known to be at the scene, is the bowfin fish. Although we can’t rule out other predators, a bowfin is our current suspect, so to speak.” 

Fish and other animals have been known to vomit a recent meal when being pursued. The reaction is believed to be a distraction for their would-be predator. Based on the recently uncovered fossil, paleontologists believe that 150 million years ago, a startled bowfin fish may have vomited up its recent meal of tadpoles and salamanders to escape a potential threat.

“This fossil gives us a rare glimpse into the interactions of the animals in ancient ecosystems,” Foster said. “There were these animals that we still have around today, interacting in ways also known today among those animals – prey eaten by predators and predators perhaps chased by other predators. That itself shows how similar some ancient ecosystems were to places on Earth today.”

The site where the regurgitated pile was found commonly produces well-preserved plant fossils such as ginkgoes, ferns, and conifers found in small ponds or lakes. The flora suggests a far more lush and wetter southeastern Utah than we have today. 

While fish, frogs, and salamanders have been found in the Morrison Formation have been found since the late 1800s, it isn’t the presence of these animals that is unusual about the fossil. In a first for the Jurassic rocks of North America, the fossil documents a predator’s meal and that predator’s need to purge the meal suddenly, for whatever reason. 

Two years ago, the same site produced a 151 million-year-old water bug known as “toe biters” in some areas.

“I was so excited to have found this site, as Upper Jurassic plant localities are so rare,” said study co-author Jim Kirkland of the Utah Geological Survey. “We must now carefully dissect the site in search of more tiny wonders in among the foliage.”