Scientists have identified a fossil of a herbivorous dinosaur. Psittacosaurusbitten by a mammal, repenomamus.
Jang Han
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Jang Han
Scientists have identified a fossil of a herbivorous dinosaur. Psittacosaurusbitten by a mammal, repenomamus.
Jang Han
When dinosaurs ruled the Earth, we tend to think of the mammals of the time—including our distant ancestors—as small and shivering in the shadows.
“We’ve always had this picture of mammals as literally the underdog,” he says. Elsa Panceroli, paleontologist at Oxford University Museum of Natural History. “They get trampled on. They cower in the dark at night, just trying to avoid being eaten.”
But a fascinating new fossil, which originated in the early Cretaceous period about 125 million years ago and is now described in the journal Scientific reports, conjures up a somewhat different possibility. It consists of two intertwined skeletons – a sarcastic mammal sinking its teeth into a much larger dinosaur.
“Our best guess is that the mammals were in the middle of attacking the dinosaur,” he says. Jordan Maloneone of the authors of the new study and paleontologist at the Canadian Museum of Nature.
If true, such a revelation shakes up our traditional view of the dominance of dinosaurs and the subjugation of mammals. It refers to a more complex ancient food web in which some dinosaurs were prey and some mammals were predators.
In the case of this particular fossil unearthed in modern-day northeastern China, “it appears that these mammals were particularly brave or voracious,” says Mallon.
A fossil tells a story
The fossil has been preserved in amazing detail due to the eruption of an ancient volcano nearby, which caused sudden ash and mudflows to preserve everything in the area. Mallon says they would have buried the early horned dinosaurs and mammals right away, in the middle of an attack.
The fossil is most likely a pile of scattered bones. It is rare for a fossil to record such behavior because, unlike a bone, the behavior tends to leave no trace.
But here, the story jumps to Malone – a fight-in-rock story.
The dinosaur has been summoned Psittacosaurus“What we call the ‘parrot-beaked dinosaur’ is because it had a beak much like a parrot in eating plant matter,” Malone says. He was about the size of a small to medium sized dog.”
in the fossil Psittacosaurus On its side, its skeleton is curled up in a semicircle. Folded against a dinosaur is a mammal called repenomamuswhich Malone calls “probably a badger-sized animal.”
repenomamus It was among the largest mammals of its time. But it is no more than a third of the volume Psittacosaurus.
Malone points to the way one mammalian claw grips the dino’s lower jaw, while another grabs its hind leg. “And the lower jaw of a mammal biting into some of the rib cage of a dinosaur,” he says.
In the fossil, one mammalian claw gripped the dinosaur’s lower jaw (left), another gripped a hind leg (right), and its teeth sank into the dinosaur’s ribcage (center).
Jang Han
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Jang Han
In the fossil, one mammalian claw gripped the dinosaur’s lower jaw (left), another gripped a hind leg (right), and its teeth sank into the dinosaur’s ribcage (center).
Jang Han
For Mallon and his Chinese and Canadian colleagues, the conclusion is clear – repenomamus He was attacking a herbivorous dinosaur three times his size.
“An ecosystem full of ninjas”
Elsa Panciroli, who was not involved in the research, is not prepared to stick to this conclusion.
“Maybe the jury is out a little bit on me as to whether the Tyrannosaurus really died out, maybe only recently,” she says, or was in a very, very vulnerable state rather than being hunted down by these mammals. “
The study authors say that mammals weren’t scavenging dinosaurs because their bones didn’t contain bite marks. They say the position of the bodies indicates that an active attack is under way.
“We already knew that mammals at least occasionally preyed on young dinosaurs,” Mallon says. “What’s new here is full growth Psittacosaurus It wasn’t necessarily safe from these smaller predatory mammals.”
And Mallon points to other modern-day analogues of small animals attacking and preying on larger animals: a wolverine taking down caribou “if desperate,” or a mongoose attacking a larger rabbit.
Regardless of the fossil’s interpretation, Banquerolli says it testifies to a more elaborate Cretaceous food web. “It’s much more complex and richer than that simplistic narrative we’re used to relying on.”
It is unlikely that this type of interaction – of a smaller mammal attacking a larger dinosaur – was very common. Usually, dinosaurs devoured mammals.
Malone says, referring to dinosaurs such as raptors DaliansaurusAnd Graciliraptor And Synovinator.
This is what makes this particular specimen even more special.
“These fossilized moments in time really allow us to make these quantum leaps in our conclusions so that we can reconstruct these ancient ecosystems,” Mallon says.
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