BOULDER, Colo. – Some of the herbivorous dinosaurs that lived in the American West millions of years ago may have also eaten crustaceans from time to time, according to new research from the University of Colorado Boulder.
CU Boulder Associate Professor Karen Chin, who is also the paleontology curator at the university’s Museum of Natural History, worked with scientists at Kent State University to examine fossilized dinosaur feces samples – called coprolites – that were dug up at Grand Staircase-Escalante National Monument in Utah. The coprolites were dated to the late Cretaceous Period, about 75 million years ago, when that area would have been near an ocean.
The feces likely came from a type of duck-billed dinosaur called a hadrosaur, which was one of the most common dinosaurs of the period. Hadrosaurs grew up to 30 feet long, weighed as much as three tons, and had specialized teeth that helped grind up plant material.
But Chin was surprised to find that the Utah coprolites showed more than just plant material – they contained shells of crustaceans along with chunks of rotting wood. Chin said the crustaceans were likely living in the wood as it decayed, and the dinosaurs ate them both.
Because the unidentified crustaceans were fairly large – at least two inches in length – it’s unlikely the hadrosaurs consumed the animals by accident, Chin said.
“From what we know about dinosaurs, this was a totally unexpected behavior,” Chin said. “It was such a surprising discovery we wondered what the motivation could have been.”
That answer might lie in reproduction. Some modern-day bird species will increase their protein and calcium intake during breeding season in order to increase their chances of successful reproduction. Birds are commonly theorized to be descended from dinosaurs.
“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 wriggling when they were scooped up, the dinosaurs would have likely been aware of them and made a choice to ingest them.”