The other paleo diet: Rare discovery of dinosaur remains preserved with its last meal

Microraptor was an opportunistic predator, feeding on fish, birds, lizards -- and now small mammals. The discovery of a rare fossil reveals the creature was a generalist carnivore in the ancient ecosystem of dinosaurs.

Finding the last meal of any fossil animal is rare. When McGill University Professor Hans Larsson saw a complete mammal foot inside the rib cage of the small, feathered dinosaur, his jaw dropped. Of the many hundreds of carnivorous dinosaur skeletons, only 20 cases preserve their last meals. This new find makes 21.

"At first, I couldn't believe it. There was a tiny rodent-like mammal foot about a centimeter long perfectly preserved inside a Microraptor skeleton. These finds are the only solid evidence we have about the food consumption of these long extinct animals -- and they are exceptionally rare," says Larsson, who came across the fossil while visiting museum collections in China.

Microraptor was not a picky eater

Fully feathered with wings on both its arms and legs, this dinosaur is closely linked to the origin of birds. Microraptor was about the size of a crow and one of the smallest dinosaurs. The first specimen was discovered in deposits in Liaoning, China, in the early 2000s.

"We already know of Microraptor specimens preserved with parts of fish, a bird, and a lizard in their bellies. This new find adds a small mammal to their diet, suggesting these dinosaurs were opportunistic and not picky eaters," says Larsson who is a Professor of Biology at the Redpath Museum of McGill University.

"Knowing they were not specialized to any particular food is a big deal," he adds. According to the team of researchers, this could be the first evidence of a generalist carnivore in dinosaur ecosystems. Generalist predators are important stabilizers in today's ecosystems, like foxes and crows, because they can feed among several species that may have differing population abundances.

"Knowing that Microraptor was a generalist carnivore puts a new perspective on how ancient ecosystems may have worked and a possible insight into the success of these small, feathered dinosaurs," says Larsson.