In the stomach of a fossilized dinosaur, researchers have discovered a complete foot of a small mammal. Before dying, the Microraptor had devoured a mammal the size of a mouse, report the scientists around the zoologist David Hone from the Queen Mary University of London in the journal Journal of Vertebrate Paleontology. This is the fourth finding of prey in a Microraptor’s stomach, following the remains of a fish, a bird and a lizard-like animal. The researchers cannot say whether the dinosaurs hunted the mammal or consumed it as carrion.
The feathered, bird-like microraptors (“little predators”) lived in the early Cretaceous period, beginning around 145 million years ago; Fossils have been discovered in Liaoning province in northeast China. The specimens found so far were less than a meter long and had wing-like front and rear legs. They lacked muscles to flap their wings, but the animals were probably capable of gliding. The currently examined specimen is a Microraptor zhaoianus. A second species is known, the Microraptor gui.
Remains of what dinosaurs ate are discovered extremely rarely
“I couldn’t believe it at first,” said co-author Hans Larsson of McGill University in Montreal, according to a statement from the university. “There was a tiny, about an inch long, rodent-like mammalian foot preserved entirely inside the Microraptor skeleton. These finds are the only reliable evidence we have of the long-extinct animals’ diet – and they are extremely rare.” Larsson reportedly came across the fossil while visiting museum collections in China.
Determining the diet of extinct creatures millions of years after they disappeared is problematic, the team writes in the study. For one thing, after devouring and digesting prey, there would be little left that could petrify. Any surviving remains are also accessible to scavengers after the dinosaur’s death and exposed to destructive environmental processes.
The fossil now examined shows a few other bones in addition to the foot, enclosed in the chest. The researchers write that other parts of the mammal may have been preserved. They deduce from the structure of the foot that the remains belong to a mammal.
The find, along with previous discoveries, indicates that microraptors were not particularly choosy. “Knowing that they weren’t locked into a specific prey is a big deal,” says Larsson. “The realization that the Microraptor was a versatile carnivore opens up a new perspective on how these past ecosystems functioned and provides insight into the success of these small, feathered dinosaurs.”