The world was a dangerous place for the first birds. Palaeontologists have found a fossil bird preserved where the stomach of a dinosaur would have been – the first direct evidence that dinos preyed on their feathered relatives.

Palaeontologists have long suspected that birds made up part of the predatory dino diet, but proof has been lacking. No longer: Jingmai O'Connor and colleagues at the Chinese Academy of Sciences in Beijing found the near-intact skeleton of a primitive bird nestling suspiciously inside a fossilised predator.

The bird belonged to an extinct group called Enantiornithes and was lying in the ribcage of an early Cretaceous winged theropod called Microraptor gui. They were part of the prehistoric ecosystem known as the Jehol biota, which existed in what is now China and has also yielded numerous spectacular feathered dinosaurs.

The bird skeleton was nearly intact, suggesting it was swallowed whole as live prey rather than scavenged.

Not only do the remains provide clues as to how and what the dinosaur ate, but also where it hunted. The bird's feet were adapted for perching, suggesting it lived in trees. Microraptor had four wings, which may have allowed it to glide between trees to hunt prey there, says O'Connor's team.

Luis Chiappe at the Natural History Museum of Los Angeles County says we need to be cautious about reaching that kind of conclusion, however. "The fact that Enantiornithes are largely viewed as arboreal animals doesn't mean that they didn't frequent the ground – like most living arboreal birds, from parrots to woodpeckers," he says.