Fossilized dinosaur feces reveal flexitarian diet

by Mary Caperton Morton
Thursday, December 14, 2017

Fossilized feces tell paleontologists a lot about what dinosaurs ate. Some unusual coprolites discovered in Utah’s Grand Staircase-Escalante National Monument may indicate that normally herbivorous dinosaurs occasionally ate crustaceans.

“From what we know about dinosaurs, this was a totally unexpected behavior,” said lead investigator Karen Chin, a paleontologist at the University of Colorado Boulder, in a statement. “It was such a surprising discovery we wondered what the motivation could have been.” Chin and colleagues found 5-centimeter-long crustacean shells embedded in bits of rotting wood in 10 different coprolite samples. The large size and prevalence of the shells indicated the ingestion was likely intentional, they suggested in a study in Scientific Reports.

“While it is difficult to prove intent regarding feeding strategies, I suspect these dinosaurs targeted rotting wood because it was a great source of protein in the form of insects, crustaceans and other invertebrates,” Chin said. “If we take into account the size of the crustaceans and that they were probably wiggling when they were scooped up, the dinosaurs would have likely been aware of them and made a choice to ingest them.”

The coprolites are likely from duck-billed hadrosaurs, the team suggested, which weighed up to 3 tons and were normally vegetarians. The animals' forays into eating seafood may have been tied to reproduction, Chin said, noting that modern birds are known to seek out foods rich in protein and calcium during the breeding season. Similar strategies may have been advantageous to species living in southern Utah during the Cretaceous, when the landscape there was inundated by shallow seas.

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