Jurassic ‘vomit’ discovered in Utah

In Jurassic times, a creature gorged itself on small prehistoric amphibians before regurgitating its meal. Several tens of millions of years later, paleontologists discovered the remains of this regurgitality (fossilized remains of the contents of an animal’s stomach). Their work is published in the journal Palaios.

The researchers made this incredible discovery four years ago during an excavation carried out in the Morrison formation, in southeastern Utah (United States). The site, which stretches across the American West, is known for its many fossils dating from the late Jurassic (164 to 145 million years ago). The section studied, dubbed the “Jurassic salad bar” by paleontologists, typically contains the fossilized remains of plants and other organic material, not animal remains.

Because of this, the researchers were surprised to find a small, compact pile of regurgitated fossilized bones that measured no more than a square centimeter.

The remains of small amphibians

Initially, researchers thought they had simply discovered the bones of a creature, possibly an ancient salamander. Very quickly, they finally realized that the pieces of the puzzle did not match.

According to them, the remains belonged to at least two amphibian species (a salamander and a frog). These remains included nearly a dozen fragments of femurs and vertebrae, as well as a fossilized soft tissue matrix. The remains of the salamander could represent a juvenile of the species Valdotriton or Comonecturoides. A priori, it is not a new taxon. Frog material, on the other hand, is not identifiable to a specific taxon.

Therefore, the authors have proposed the idea of ​​regurgitation, imagining the remains of a meal regurgitated by an ancient predator. The hypothesis of coprolites (fossilized excrement) did not indeed hold, because the latter only offer fully digested content, which was not the case here.

The regurgitalite contains nearly a dozen bones from at least two species of amphibians. Credits: John Foster
vomit regurgititis
Artist’s rendition of a fish regurgitating a frog. Credits: illustration by Brian Engh

Although there have been a number of recorded finds of regurgitality around the world, this is the earliest known example in the Morrison Formation. There’s currently no way to know exactly which species vomited up its meal millions of years ago, but researchers believe it could be a fish or semi-aquatic mammal.

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