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New evidence from pterosaur's fossilized stomach helps settle longstanding debate about its diet

The Mesozoic pterosaur is considered to be the first vertebrate to achieve powered flight and new evidence, also the first of its kind, helps to pin down what exactly this flying reptile ate. Previously, scientists had trouble establishing a consensus on the pterosaur's diet. Some suggested meat-based or fish-based diets, while others believe the pterosaur ate plants, bugs, or even that the pterosaur was a filter-feeder.

Prior evidence for the pterosaur diet was mainly based on indirect evidence related to their morphology or features of their anatomy, the structure of their beak being one example. A few studies have found remnants of food in pterosaur remains, either within the stomach, the mouth or as waste products. These included some evidence of fish and insect consumption. However, new research discussed in a from Science Bulletin provides the first direct evidence that pterosaurs were perfectly happy to eat a full meal of plant material.

The report details the findings of a well-preserved young pterosaur, specifically Sinopterus atavismus, from the Lower Cretaceous Jiufotang Formation in western Liaoning, China. In addition to the specimen being almost entirely intact, the pterosaur had a full stomach. The researchers found an abundance of phytoliths—tiny particles from plant cells— within the fossilized stomach.

Phytoliths have been found in the stomachs of other plant-eating dinosaurs, but never in pterosaurs before this discovery. The researchers note that these phytoliths were not found anywhere else in the immediate area, indicating that they did indeed originate from the pterosaur's stomach. Gasotroliths—a type of stone found in the stomach of some plant-eating animals to help them grind plant material—were also found in the stomach contents, which adds additional support to the conclusion that the pterosaur ate plants.

A total of over 320 phytoliths were removed from the specimen. However, precise plant identification is difficult due to the lack of prior research regarding the diversity of ancient phytoliths. But the study authors do note that the contents appear to indicate multiple plant types.

They write, "Phytolitholith morphologies in the stomach contents, with this high diversity, are nearly impossible to attribute to one single taxon based on the recent knowledge, which suggests that Sinopterus might have consumed a diverse range of plants."

After much debate about this topic, paleontologists now have a clearer answer as to the diet of the pterosaur. Still, more research is needed to determine more about the diversity of foods that might have been included in their diet and it's probably fair to say that these scientists hope to have luck in finding similarly preserved specimens to provide further elucidation for future studies.