How 2 pterosaurs’ last meals ended up in the fossil record
Fur, bones, feathers and scales can be murder on the digestion. So predators that gulp their prey down whole face a conundrum: What do you do with the indigestible bits? Owls and other birds of prey cough up anything unusable. If you’ve been to a science museum, you may have dissected one of the products of these digestive outbursts, known as owl pellets.
It appears that flying predators were coughing up big pellets in the dinosaur era, too. In a paper published in the journal Philosophical Transactions of the Royal Society B, Chinese paleontologists announced the discovery of a pair of pterosaurs, each preserved in fine detail — along with the pellets left over from parts of their meals. The find adds another animal to the history of life that spit out food it couldn’t digest.
According to Shunxing Jiang, a paleontologist with the Chinese Academy of Sciences and an author on the study, some researchers had suspected that pterosaurs might be capable of producing pellets, considering their close evolutionary relationship with dinosaurs, which also left pellets in the fossil record. But none had ever been found.
The team examined a pair of well-preserved specimens of Kunpengopterus, which inhabited forests on lake shores late in the Late Jurassic era some 160 million years ago. The specimens — an adult and a juvenile — both died and sank into the deep waters, where their bodies were covered by soft sediment.
The ooze at the bottom of the lake also covered large, compacted bundles of tough fish scales, in proximity to the pterosaurs. Jiang’s team found that these bundles were wider than the pterosaurs’ pelvises, suggesting that they couldn’t have been passed through the animals’ bowels.
Therefore, Jiang said, they must have been pellets, which were either coughed up immediately before the animals died, or forced from the body by the buildup of gases as the animals decayed.
“We have two specimens of one species, with similar-size pellets relative to its body size. This does not often happen in the study of vertebrate paleontology, especially pterosaurs,” Jiang said. That, he continued, “made our study more convincing.”
While Kunpengopterus might have been a small generalist predator, Jiang said, at least two individuals dined on fish before they died. These fish dinners also differed in size according to the animal’s size — by comparing the scales found in the pellets with those from complete fish, the team concluded that the juvenile pterosaur had been eating average-sized fish, while the adult had swallowed something considerably larger.