A cat-sized dinosaur’s surprising lunch has been discovered in a 120-million-year-old Microraptor fossil. Although the fossil was first described in 2000, it hid an intriguing and historical secret: A re-analysis of the fossil found the foot bones of a mammal in the raptor’s thorax – the first evidence of a dino eating a mammal.
The find, described Tuesday in the Journal of Vertebrate Paleontology, builds on previous research by the Microraptor zhaoianus Fossil discovered in the Jiufotang Formation in western China. This fossil is missing the middle part of its body, but the thorax is visible and within it the bones of a tiny right foot, less than half an inch in size, were perfectly preserved.
Microraptors were three-toed, carnivorous dinosaurs that occupied the trees of old Earth and are among the smallest dinosaurs discovered. Fossils of various Microraptor species show evidence of long feathers on each limb, which may have been used for gliding.
As you might expect, eating doesn’t usually result in very well-preserved fossil remains. All of that biting and chewing and digestion usually leaves few traces of a meal. However, scientists have a pretty good idea of the microraptor diet thanks to fossils with undigested remains in their stomachs.
A bird, a fish and a squamate – the class of animals that includes lizards and snakes – have all been found before, but the new find helps paint a more complete picture of what went down the esophagus during a prehistoric tasting.
“It’s so rare to find examples of food in dinosaurs, so every example is really important because it provides direct evidence of what they ate,” said David Hone, a paleontologist at Queen Mary University of London and first author of the new study.
While scientists can tell a foot landed in the microraptor’s stomach, they’re not sure which species it belonged to. The slender digits resemble tiny extinct possum-like mammals known as Sinodelphys or whatever mouse-like Eomaia. However, the digits are not long enough to be one of these species.
Another open question is whether Microraptor preyed on the mammal or if it just ate the foot. That’s impossible to say with this fossil, but some scientists have suggested that the microraptor’s feathered limbs may have enabled the species to glide from branches to the ground to hunt terrestrial species. The size of the mammal’s foot suggests the creature was in the size range expected for microraptor prey.
The amazing fossil builds on previous evidence that these smaller, three-toed dinosaurs would feed on whatever was around – it’s even possible that they even ate plants on occasion.