A perfectly preserved fossil seems to confirm that millions of years ago some mammals hunted for dinosaurs, even if the latter were much larger than them. The discovery of the fossil in China dates back to about ten years ago, but only recently has it received new attention with one study science published in the journal Scientific Reports. However, not all experts agree on what the fossil seems to show and invite us not to jump to hasty conclusions.
In 2012 the fossil was discovered in the Chinese province of Liaoning, an area rich in remains not only of dinosaurs and pterosaurs, but also of the first mammals, birds (the only dinosaurs still alive today) and some species of amphibians. They were covered by the debris of large volcanic eruptions, thus arriving well preserved up to the present day.
The hunting scene fossil dates back 125 million years and includes the remains of a Repenomamus robustusa mammal about the size of a modern-day raccoon, and one Psittacosaurus lujiatunensis, a bipedal dinosaur with a stout, curved beak similar to that of today’s parrots. The scene, which according to the new study is hunting, would have been immobilized following a volcanic eruption, which would have led to the rapid death of both specimens buried under a thick layer of ash and mud.
According to the research team, the position of the mammal with its teeth sunk into the dinosaur’s ribcage and a paw in its beak are signs of predation activity. The fact that there are no signs of the mammal’s teeth on the dinosaur’s bones further suggests that the animal was hunting and not feeding on the carcass of an already dead animal. Jordan Mallon, one of the authors of the study, has said: “We knew that mammals occasionally hunted at least baby dinosaurs. The novelty is that even one Psittacosaurus lujiatunensis adult was not necessarily safe from predatory mammals.
Based on the size of the remains of the two animals, the research estimates that the mammal weighed about 3.4 kilograms, while the dinosaur weighed at least 23. The marked difference in tonnage and other details are what leave skeptics other experts, who did not participate in the recently published study.
The presence of the mammal’s paw in the dinosaur’s beak, for example, could suggest that the specimen of Psittacosaurus lujiatunensis was already dead, considering that its hooked beak would have easily severed the other animal’s leg. The position of the other legs of both also seems to suggest that the two animals had already died at the time of the eruption and that their bodies had fallen, perhaps from a slope.
The area in Liaoning is famous for the large amount of fossils, but in past it had happened that some counterfeit finds were passed off as real, leading to a certain distrust of some discoveries. However, the research team carried out various analyzes on the fossil of the two animals and on the sediments around the point where it was found, concluding that it is not a fake.
It is very rare that very ancient fossils are found so well preserved. Usually the fossilized bones are scattered and it is not always possible to reconstruct their correct position, as well as that of the animal at the time of its death.
The first mammals they appeared about 180 million years ago and coexisted for a long time with dinosaurs, which – apart from birds – became extinct 66 million years ago. The processes of differentiation in numerous species of mammals, however, already began in the period of coexistence with the dinosaurs, even if their prevalence on land increased after the mass extinction of the dinosaurs.