Ancient droppings suggest Late Jurassic pterosaurs ate like modern flamingos

Aug. 26 (UPI) -- New analysis of ancient coprolites -- fossilized droppings -- suggest Late Jurassic pterosaurs used a filter-feeding technique similar to modern flamingos.

Scientists studied dozens of droppings found surrounding the 150-million-year-old footprints of pterosaurs in Poland's fossil-rich Wierzbica Quarry.

Coprolites can offer paleontologists valued information about the diets of ancient species, but it's often difficult to determine which species produced the droppings.

Because the coprolites in Poland were found among dozens of pterosaur footprints, scientists could be fairly certain the ancient droppings belonged to pterosaurs, a group of flying reptiles that dominated the skies during the age of the dinosaurs. Pterosaurs are the earliest known group of vertebrates to evolve powered flight.

Back in the lab, researchers used synchrotron microtomography to analyze the insides of the ancient reptile droppings. They found the remains of a variety of food sources, including bits of foraminifera, small, shelled amoeboid protists. Scientists also found shell fragments from marine invertebrates, as well as remains of polychaete worms.

"A reasonable explanation for how a pterosaur big enough to have produced the droppings ingested such small prey is through filter feeding," study author Martin Qvarnström, a doctoral student at Uppsala University in Sweden, said in a news release.

When feeding in coastal wetlands, the Chilean flamingo is known to produce droppings filled with foraminifera.

"The similar contents of the droppings of these flamingos and the pterosaur coprolites could be explained by similar feeding environments and mesh sizes of the filter-feeding apparatus," Martin Qvarnström said. "It appears therefore that the pterosaurs which produced the footprints and droppings found in Poland were indeed the flamingos of the Late Jurassic."

Anatomical evidence suggests the pterodaustro, a ctenochasmid pterosaur slightly younger than the Polish coprolites, captured its meals via filter feeding. While older ctenochasmids had yet to evolve a sieving basket containing long, thin teeth, they did boast long snouts filled with slender teeth, a setup more than capable for filtering tiny organisms from the water.

As scientists concluded in their study, newly published in the journal PeerJ, ctenochasmids likely produced both the footprints and droppings discovered in Wierzbica Quarry.