Researchers from the University of Alberta found fossilised remains of three flying dinosaurs in the belly of a raptor-like predator called Sinocalliopteryx.
Sinocalliopteryx was about two metres in length and roughly the size of a modern-day wolf.
Sinocalliopteryx's meals were three flying Confuciusornis. Confuciusornis was one of the earliest birds and had a crude version of a modern bird's skeleton and muscles.
Researchers said such primitive birds were probably limited to slow take-offs and short flights.
"Sinocalliopteryx didn't have wings or the physical tools needed to be an adept tree climber," co-author Scott Persons, said.
"The fact that this Sinocalliopteryx had, not one, but three undigested birds in its stomach indicate it was a voracious eater and a very active hunter," Persons said.
The fossil skeleton was found in China's Liaoning region along with a second Sinocalliopteryx.
The second dinosaur had eaten a Sinornithosaurus, a small feathered meat-eater about the size of a house cat that may have been able to fly or glide short distances.
