Sometime during the Cretaceous Period, 120 million years ago, a dinosaur wolfed down its last meal — a small mammal the size of a mouse. And it's still there.
A researcher with a sharp eye spotted the mammal's foot preserved inside the guts of a fossilized Microraptor zhaoianus, a feathered therapod less than a meter (3 feet) long.
"At first, I couldn't believe it. There was a tiny rodent-like mammal foot about a centimeter (0.4 inch) long perfectly preserved inside a Microraptor skeleton," said Hans Larsson, a professor of biology at McGill University's Redpath Museum in Montreal. Larsson came across the fossil while visiting museum collections in China.
"These finds are the only solid evidence we have about the food consumption of these long extinct animals — and they are exceptionally rare," Larsson said in a news release.
The research, which was published in the Journal of Vertebrate Paleontology on December 20, said this was only the 21st known example of a fossilized dinosaur with its last meal preserved.
It's rarer still to find that a mammal was on the menu; there's only one other such example currently in the fossil record.
"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," Larsson, a coauthor of the study, said in a statement.
"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," he explained.
Generalist predators, like foxes and crows, are important stabilizers in today's ecosystems because they can feed on several species, the news release said. According to the research, the Microraptor is the first known example of a generalist carnivore in a dinosaur era.
It was possible that other dinosaurs from the therapod family, which included the Tyrannosaurus rex, might also have shared a similarly unfussy diet, the study said.
The Microraptor fossil was discovered in the rich fossil deposits in Liaoning in northeastern China in the early 2000s. The specimen, which features plumage on its arm wings and legs, was one of the first feathered dinosaurs to be unearthed.
"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," said study coauthor Dr. David Hone, a reader in zoology at Queen Mary University of London, in a statement.
"This study paints a picture of a fascinating moment in time — one of the first record(s) of a dinosaur eating a mammal — even if it isn't quite as frightening as anything in 'Jurassic Park'."
CNN
