Paleontologists find fossil of ancient vomited amphibians

SALT LAKE CITY — Paleontologists in southeastern Utah discovered ancient remains that appear to be amphibians that were regurgitated by their predator at least 1,500 million years ago.

According to a release from Utah Division of State Parks, the fossil was found in rocks of the Morrison Formation, a Late Jurrassic-age layer famous for the stegosaurus and brachiosaurus, along with frogs and tadpoles, salamanders, fish, and a variety of plants.

This particular site represents a pond deposit with well-preserved flora fossils including ginkgoes, ferns, and conifers, along with amphibians and fish. The once wetter and more lush site also produced the second insect fossil known from the formation, the giant water bug relative Morrisonnepa.

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

The amphibian bones found at this site are some of the smallest in its layer, measuring as small as 0.12 inches in length. Based on chemistry, arrangement, concentration, and array of animal bones, paleontologists say the pile indicate that at least two creatures were present. One a salamander, and one that may have been a tadpole.

The predator is believed to be an aquatic or semi-aquatic mammal. Animals including fish will sometimes vomit their recent meal when threatened.

“We can’t be sure, but among the animals of interest here, the current best match, and the one known to be at the scene, is the bowfin fish,” co-author of the study John Foster said. “This fossil gives us a rare glimpse into the interactions of the animals in ancient ecosystems.”

Though fish and amphibians have been found in the Morrison Formation since the late 1800s, this fossil is the first in Jurassic rocks of North America to document not only a predators meal but the need to suddenly purge that meal.

The study on the “fish-puked tadpole” was recently published in the journal Palaios.