This fossilized vomit is older than the dinosaurs

This fossilized vomit is older than dinosaurs

By Meghan Bartels edited by Andrea Thompson

Fossils are remarkable for their ability to viscerally connect us to long-lost life. Most of a Tyrannosaurus rex skull, the biting point of a shark’s tooth, the surprising familiarity of a hominid footprint—and then there’s the charm inherent in any sample of regurgitality, the paleontological term for fossilized vomit.

Okay, the charm may be exaggerated, but for the good scientist, rare discoveries are “little treasures,” explains research doctor Arnaud Rebillard. candidate in paleontology at the Natural History Museum in Berlin. Let’s take the example of regurgitation which is the subject of research published by Rebillard on January 30 in Scientific reports—the oldest known regurgital from a terrestrial ecosystem.

Found in 2021, the specimen comes from a 290 million year old German site called Bromacker. During a century of digging, paleontologists saw a valley full of conifers that were apparently teeming with vegetarians, says Amy Henrici, retired paleontology collection manager at the Carnegie Museum of Natural History, who was not involved in the new research.

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Amid the loose fossils and remarkably preserved skeletons that characterize the site, the regurgital was uninteresting until the process of cleaning the fossils and a computed tomography (CT) scan provided a clearer view. This process digitally extracted a group of 41 small bones that turned out to belong to three distinct species: two small reptiles and a larger reptile-like animal.

“It was clearly something that was eaten and then ejected from an animal,” Rebillard says. The following questions were obvious: what extremity did the fossil come from and what type of animal had expelled it?

The most famous counterparts of regurgitites are coprolites, or fossilized excrement. (There are also gastrolites and cololites, which preserve the contents of the digestive tract in place in the stomach and intestines, respectively. Together, these types of fossils are known as bromalites.) The distinction between coprolites and regurgitates is “actually not always very obvious,” Rebillard says.

In this case, two pieces of evidence led Rebillard and his colleagues to conclude that the remains had been vomited: The leg bones of the larger prey remained connected to each other, suggesting that the limb had not passed through an entire digestive system. And the material directly surrounding the bones was low in phosphorus, which is abundant in fossils that were once poop.

As for who the scientists were thinking about, there are two known species at the Bromacker site that would have been large enough to eat animals of the size found in the regurgitation: Dimetrodon teutonis (a small member of a group of sailing animals that are often confused with dinosaurs) and Tambacarnifex unguifalcatus. Both contenders are synapsids, or members of a group including mammals and their extinct relatives, and would have been about 20 to 30 inches long without their tails.

Regardless of the predator involved, Henrici notes that the regurgitation confirms that one of these animals nibbled extensively on the small creatures around it and could vomit up indigestible material, much like modern owls and Komodo dragons do today. For Rebillard, the fossil is also proof that the three prey species not only lived together at the same geological time, but also died together within the same week or even day.

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