The Oldest Known Land Animal Vomit Reveals a Savage Prehistoric Food Web

Ancient fossilized vomit reveals one of the earliest snapshots of life on land.

Nearly 290 million years ago, a predator roaming a river valley on the supercontinent Pangaea ate more than it could chew. It devoured several animals—and later expelled the remains.

That moment of indigestion somehow survived the rise and fall of the dinosaurs, hardening into a “regurgitalite” that scientists now say is the oldest fossilized land-animal vomit ever discovered.

Inside the small rock is a cluster of bones from several prey animals, preserved together in a single event. “It’s kind of like a photograph of a moment in the past that is telling us about the animal that was living,” said paleontologist Arnaud Rebillard of the Museum für Naturkunde in Berlin, speaking to Science News. “Any data that we can find about their behavior is very precious.”

The discovery, reported in Scientific Reports, provides an unusually direct look at predator behavior around 60 million years before the first dinosaurs appeared.

A Fossilized Buffet

The fossil vomit was found at the Bromacker site in central Germany, one of the few sites that preserves a fully terrestrial ecosystem from the early Permian period (299–251 million years ago). During that era, streams and vegetation spread across the region’s floodplain.

When researchers examined the lump, they realized something strange. Instead of scattering, the bones clustered tightly together. Micro-CT scans later revealed a compact cluster of 41 bones embedded inside the stone.

The bones came from at least three animals.

Some belonged to a small parareptile about 10 centimeters long called Thuringothyris mahlendorffae. Others matched Eudibamus cursoris, another small reptile from the same ecosystem. A third bone came from a much larger herbivore related to Diadectes.

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The only explanation for the distribution of the bones is that these ancient animals were at some point eaten and thrown up.

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The sticky mixture of mucus, stomach fluids and bones can form a compact pellet. If buried quickly, it can fossilize.

On land, evidence like this almost never survives for more than a few days. This prehistoric vomit survived because it was likely buried by a sudden flood of sediment immediately after being expelled, sealing it in an oxygen-free “time capsule” before scavengers or weather could destroy it. Over millions of years, minerals replaced the organic material in the bone cluster.

“Regurgitalites are direct witnesses of the behavior of an animal,” Rebillard told IFLScience. “This is going to give us very important clues about the food web that existed back then, and we’re speaking about 290 million years ago.”

Tracing the Predator

Figuring out whether the fossil was vomit or feces took careful detective work.

In feces, known as coprolites, digestion usually breaks down the bones and leaves them surrounded by phosphorus-rich material. In this fossil, the surrounding sediment contained very little phosphorus, a chemical signature consistent with regurgitated material rather than waste.

The bones themselves were also unusually intact. Some were even aligned or partly articulated, suggesting they had not spent long in a digestive tract before being expelled.

Together, the clues pointed strongly to fossilized vomit.

The culprit remains uncertain. But scientists have narrowed the suspects to two predators known from the same fossil beds: Dimetrodon teutonis (small one on the middle-bottom) and Tambacarnifex unguifalcatus, both synapsids, the evolutionary lineage that eventually gave rise to mammals.

Neither predator likely chewed its prey much. Instead, the animal probably swallowed large chunks—or entire animals—then later expelled the hardest parts.

That behavior is common today. Many carnivores regurgitate bones, hair and other materials that are hard to break down in the gut. The fossil suggests that ancient predators behaved in much the same way.

Because the lump contains bones from multiple species, it also hints at the feeding strategy of the predator. The mixture points to opportunistic hunting, grabbing whatever animals were available rather than specializing in a single prey.

“We need fossils like this to really tie together how the ecosystem functioned and how the food webs were structured,” said paleontologist Martin Qvarnström of Uppsala University.

Most earlier regurgitalite examples come from marine environments. Terrestrial ecosystems rarely preserve such delicate evidence of behavior. That makes this unpleasant relic surprisingly valuable.

“In this small cluster that you can hold in your hands, you have three animals that you can literally say were truly existing in the same place and at exactly the same time,” Rebillard told IFLScience. “To have this temporal resolution for an environment that is almost 300 million years old is absolutely crazy—it’s going to bring us plenty of new data on the palaeoecology that existed back then.”

For paleontologists, it’s the closest thing to a freeze-frame of a meal that happened nearly 300 million years ago.