Determining the diet of non-avialan dinosaurs is problematic owing to the often sparse and non-specific nature of the data available in the fossil record. This is because animals consumed by carnivores, either partially or entirely, were likely to be involved in a process limiting their preservation potential.
A new study by McGill University describes the remains of a small fossil mammal foot preserved inside the body cavity of the holotype specimen of the small feathered dinosaur Microraptor zhaoianus. Microraptor preyed on fish, birds, lizards, and now small mammals as opportunistic predators. The discovery of a rare fossil suggests the animal was a generalist carnivore in prehistoric dinosaur ecology.
Of the hundreds of carnivorous dinosaur skeletons, only 20 cases preserve their last meals. This new find makes 21.
McGill University Professor Hans Larsson said, “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.”
Larsson said, “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.”
“Knowing they were not specialized to any particular food is a big deal; 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.”