Determining the diet of non-avial dinosaurs is problematic due to the often sparse and non-specific nature of the data available in the fossil record. This is because animals that were consumed in whole or in part by carnivores were likely involved in a process that limited their conservation potential.

A new study from McGill University describes the remains of a small mammalian fossil foot preserved in 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 chests store their last meals. This new find makes 21.

McGill University Professor Hans Larsson said: “At first I couldn’t believe it. There was a small rodent-like foot of a mammal about an inch long, perfectly preserved in 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.”

Image by Hans Larsson.

Microraptor was fully feathered with wings on both its arms and legs. About the size of a crow and one of the smallest dinosaurs, the dinosaur is closely linked to the origins of birds.

Larson said: “We already know of Microraptor specimens that have been preserved with parts of a fish, a bird and a lizard in their abdomens. This new find adds a small mammal to their diet, suggesting that these dinosaurs were opportunistic rather than picky eaters.”

“Knowing they don’t specialize in a 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, such as foxes and crows, because they can feed on different species that can have different population abundances.”

“Knowing that Microraptor was a generalist carnivore gives a new perspective on how ancient ecosystems may have worked and a possible insight into the success of these small, feathery dinosaurs.”

Magazine reference:

  1. David Hone, Alexander Dececchi, Corwin Sullivan, Xu Xing, and Hans Larsson. The generalist diet of Microraptor zhaoianus included mammals. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2022.2144337