Scientists believe they may have uncovered the first known incident of a mammal being eaten by a dinosaur.
Palaeontologists in the UK have analysed fossil remains from around 120 million years ago, showing a small, feathered dinosaur – known as Microraptor – with the foot of an animal inside its ribcage.
The experts said their findings, published in the Journal of Vertebrate Paleontology, is “the first record of a dinosaur eating a mammal”.
Dr David Hone, from Queen Mary University of London, who is first author on the study, said: “It’s so rare to find examples of food inside dinosaurs, so every example is really important as it gives direct evidence of what they were eating.
“While this mammal would absolutely not have been a human ancestor, we can look back at some of our ancient relatives being a meal for hungry dinosaurs.
“This study paints a picture of a fascinating moment in time – the first record of a dinosaur eating a mammal – even if it isn’t quite as frightening as anything in Jurassic Park.”
Microraptors lived in the ancient forests of what is now China, somewhere between 125 and 113 million years ago.
While it moved on its two legs, experts believe some species may have been capable of guided flight.
About the size of a crow or a small cat, Microraptors would have been gliding from tree to tree to prey on small animals.
Although the specimen was first described in 2000, the researchers said the previous team had failed to see the remains of another animal inside the dinosaur.
Microraptor would have been an easy animal to live with but a terror if it got out— Dr Alex Dececchi
Further analysis suggests the prey was a mammal about the size of a mouse, which likely lived on the ground and was not a good climber.
Previous research has shown other Microraptor specimens with preserved food in their stomachs, such as a bird, a lizard and a fish.
However, the team added that it is not certain if these dinosaurs had directly preyed on these animals or found them already dead and had scavenged them.
Dr Alex Dececchi, from Mount Marty College in South Dakota, US, and one of the study authors, said: “The great thing is that – like your housecat, which was about the same size – Microraptor would have been an easy animal to live with but a terror if it got out, as it would hunt everything from the birds at your feeder to the mice in your hedge or the fish in your pond.”