The work of a paleontologist is often like solving a puzzle with no picture in the box and most of the pieces missing. From scattered bones and teeth, scientists who study fossils extrapolate entire long-dead creatures, and even relationships between different species. But every so often, researchers get a lucky break in the form of nearly complete skeletons, their bodies preserved in a way that offers a glimpse of their behavior in life.
This may be the case with a newly described fossil of a badger-like mammal and a Labrador retriever-sized dinosaur, locked in what appears to be an eternal tangle. A mixed team of Canadian and Chinese researchers published their findings in the journal Scientific Reports on Tuesday, including a section of the study devoted to addressing concerns that the fossil is a fake.
The prehistoric skirmish took place about 125 million years ago, in what is now northeastern China, and seems to be a similar man-bites-dog story during the dinosaur era. Usually at that time, according to conventional wisdom, mammals were tame, eking out a feeble existence while the terrible reptiles shook the earth around them. But the unlikely fossil depicts a battle between a mammal called Repenomamus robustus and a bipedal, plant-eating relative of Triceratops called Psittacosaurus lujiatunensis.
In size, the dinosaur had the advantage, but Repenomamus, preserved with its teeth clamped in the rib cage of Psittacosaurus, appears to have punched well above its weight. The dinosaur’s bones show no evidence of gnawing by scavengers, indicating that the Repenomamus encounter occurred when Psittacosaurus was still alive.
“There are examples today of small carnivorous mammals taking on larger prey,” said Jordan Mallon, a paleontologist at the Canadian Museum of Nature and a co-author of the study. He pointed to the wolverines taking down the caribou. He added, “We think it’s likely that Repenomamus was a small, ferocious predator that was willing to take down prey larger than itself if necessary.”
Taking care of animals in the middle of a melee requires a lot of luck (or bad luck, from the animals’ point of view). It started with a volcanic eruption, spewing ash. That ash can be turned into mudslides by seasonal flooding or heavy rains. Then, while these Repenomamus and Psittacosaurus were fighting, “this kind of mud flow caught them and preserved them for 125 million years,” said Dr. Mallon.
The fossil was unearthed in 2012 by farmers in the Chinese province of Liaoning and obtained by Gang Han of Hainan Vocational University of Science and Technology, a co-author of the study. The find is incredible, and there are many cases when such discoveries turn out to be too good to be true. Fossil forgeries, including separate specimens put together to complete a skeleton or a scene, are “a huge problem,” Dr. Mallon. “It’s a concern that we have, and so we have to do our homework to at least convince ourselves” that it’s legitimate.
said Dr. The researchers carefully excavated the rock surrounding the fossils and found that the mammal’s left lower jaw “actually plunged into the rock and actually bit the dinosaur’s ribs,” rather than being pieced together by a fossil forger. . The researchers also examined the rock in the fossil and the rock from the fossil bed where it was supposedly found; they match. Based on these independent lines of evidence, “we feel satisfied that this is a genuine fossil and not a fake,” said Dr. Mallon.
Or if it’s fake, he says, it’s “the best I’ve ever seen.”
David Grossnickle, an evolutionary biologist at the University of Washington who was also not involved in the study, said that while in the “worst case scenario,” parts of the fossil specimen could be fake, the skull of a mammal bit into a dinosaur bone. . looks real, and that piece alone is “an incredible fossil.”
Without presenting a convincing challenge to its authenticity, the fossil offers tantalizing evidence of how mammals and dinosaurs interacted.
“We rely on amazing fossils like this to really fill in the gaps of how these ancient ecosystems functioned, because we don’t always rely on bones alone to tell us these stories,” said Dr . Mallon.
Michael Pittman, a paleontologist at the Chinese University of Hong Kong who was not involved in the study said that the immortal bite does not mean that Repenomamus hunted dinosaurs for food and that the animals may have engaged with lesser predators. takedown and more of a “scuffle.”
But the study could contribute to the “growing evidence that Mesozoic mammals were more ecologically diverse than we classically thought,” said Dr. Grossnickle, “and getting a little revenge, I guess, on those big dinosaurs.”