An international team of scientists has discovered the first evidence of a dinosaur devouring a mammal. The group re-examined a fossil that was discovered more than 20 years ago to come to this conclusion. This discovery was published in the Journal of Vertebrate Paleontology.
The findings build on those of a previous team that studied the fossil Microraptor zhaoianus in 2000. It was discovered in the Jiufotang Formation in western China. The research team dated it to around 120 million years ago. They noted that the fossil was missing most of its middle section but retained its rib cage.
Microraptors were three-toed dinosaurs that were carnivores like their larger cousins. They lived in trees and were about the size of a modern house cat in comparison to other dinosaurs. Some microraptors had feathers. These feathers could have been used to glide down from tree perches.
The researchers discovered evidence of another fossil inside the microraptor. This fossil once belonged to a tiny mammal in this new effort. A small fossil mammal foot was discovered just behind the ribs. It indicates that the larger creature had devoured a mouse-sized mammal.
Prior research has shown that dinosaurs ate other small creatures such as snakes, squamates and birds. But have never eaten a mammal. According to the researchers, the lack of mammal remains inside dinosaur stomachs is likely due to the rarity of finding any remains of other creatures inside dinosaurs.
The researchers have also been studying the foot of the microraptor’s remains. But they are yet to determine which type of mammal they belonged to. It had thin toes, like modern possums, but it was shorter. The researchers are also investigating whether the dinosaur actively pursued and ate the mammal or if it was merely scavenging. They point out that if it had glider-like wings. The wings could have swooped down and caught a small creature like the one found in its gut.
More information: David W. E. Hone et al, Generalist diet of Microraptor zhaoianus included mammals, Journal of Vertebrate Paleontology (2022). DOI: 10.1080/02724634.2022.2144337