‘Jurassic vomit’ gives clues about prehistoric animal feeding

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Some 150 million years after they were expelled by an as-yet-unidentified animal, likely a small fish or semiaquatic mammal, fossilized remains of regurgitated food now serve as an important source of scientific information.

The sample of “prehistoric vomit” was analyzed by a team of American researchers, in an article published in the specialized magazine Palaios.

“The interesting aspect of bromalites [restos fossilizados de material proveniente do sistema digestivo] is the potential for us to have direct evidence about the food items of animals”, explains the leader of the work, John Foster, from the Utah Natural History Museum Park, in the United States.

The remains were found in a region in southeastern Utah known to paleontologists as the “Jurassic Salad Buffet” due to the abundant presence of fossilized plants.

The site conditions were considered crucial for the preservation of the sample.

“As with many fossils, a key point for preservation is the relatively rapid burial and the lack of deterioration by scavengers or bacteria doing decomposition. This environment, [que era] a pond or a lake, seems to have provided that,” says Foster.

“Even more impressive is the fossilized preservation of entire soft leaves in the same location, in many cases with the cuticle intact as well”, he details.

Although it is a very compact sample, measuring about 1.33 cmtwo, the specimen brings together more than 20 small bones and other materials. By analyzing the contents, the scientists identified that the “meal” possibly included small frogs and even a tiny salamander.

An important part of the work was to differentiate whether the mass found was a vomit or a stool sample. For this, the group took into account a series of characteristics of the material, from coloration, thickness and even the presence of sediments.

The absence of “significant volume of soil mass” among the identified bone elements was one of the points that helped to suggest that it was regurgitated material. Another determining issue was the state of the fossilized material.

“Many of the bones are delicate, sharp elements that would hardly survive complete digestion without undergoing breakage and dissolution,” the article says.

Also by the state of processing of fossilized material, scientists consider that the predator did not chew well before swallowing its prey.

The main hypothesis raised by the researchers is that a small animal, such as a fish or a semiaquatic mammal, regurgitated the material.

“Fish sometimes regurgitate fully swallowed food when threatened, for example if being chased in experimental settings, and also regurgitate partially ingested remains of relatively large prey,” the researchers exemplify.

In the assessment of the research leader, John Foster, the similarities between the behavior of animals in the Jurassic and today is one of the most interesting points of the work.

“This fossil shows interactions between prey and predators that are very familiar to us. This is a scene we can witness in today’s swampy environments,” he says. “Not all aspects of life during the Late Jurassic were different than they are today,” she adds.

The study of prehistoric animal droppings —including faeces (coprolites) and urine (uroliths)—is already a well-established domain in paleontology, particularly with material relating to dinosaurs.

In the field of prehistoric pee, Brazil is one of the great references. In 2004, it was a study published by Brazilian paleontologists that helped to confirm the liquid excretory system of dinosaurs, and national scientists are among the leading experts in the area.

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