The surprising lunch of a cat-sized dinosaur 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 reanalysis of the fossil found a mammal’s foot bones in the raptor’s ribcage — the first evidence of a dino dining on a mammal.
The find, described in the Journal of Vertebrate Paleontology on Tuesday, builds on the researchers’ previous research. Microraptor zhaoianus fossil, discovered in the Jiufotang Formation in western China. That fossil is missing the middle part of its body, but the ribcage is visible, and inside, the bones of a small right foot, less than an inch in size, were perfectly preserved.
Microraptors were three-toed, carnivorous dinosaurs that inhabited the trees of ancient Earth and are among the smallest dinosaurs discovered. Fossils of several microraptor species show long feathers on each limb, which may have been used for gliding.
As you might expect, being eaten usually doesn’t lead to very well-preserved fossil remains. All that biting and chewing, plus digestion, typically leaves little trace of a meal. However, scientists have a pretty good idea of the microraptor’s diet thanks to fossils with undigested remains in the stomach.
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 passed down the esophagus during a prehistoric degustation.
“It’s so rare to find examples of food in dinosaurs, so each example is really important because it gives direct evidence of what they were eating,” said David Hone, a palaeontologist at Queen Mary University of London and first author. of the new study.
While scientists can see that a foot ended up in the microraptor’s stomach, they aren’t sure what species it belonged to. The slender digits are similar to small, extinct, possum-like mammals known as Sinodelphys or the more mousy Eomaia. However, the numbers are not long enough to be one of these species.
Another unresolved question is whether Microraptor hunted the mammal or whether it preyed only on the foot. That’s impossible to say with this fossil, but some scientists have suggested that the microraptor’s feathery limbs may have enabled the species to glide from branches to the ground to prey on terrestrial species. The size of the mammal’s foot suggests the creature would have been in the size range expected for microraptor prey.
The amazing fossil builds on previous evidence that these smaller three-toed dinosaurs feasted on whatever was around — it’s even possible they even ate plants on occasion.