Dinosaur cannibalism was real, and Colorado paleontologists have the bones to prove it

A series of bite marks on fossil bones in what is now Colorado show that the Jurassic dinosaur Allosaurus was not afraid to eat its own kind. The results are the first direct evidence of cannibalism in this group of predatory dinosaurs, paleontologists reported May 27 in the journal PLoS ONE. The researchers also found an unusually large number of bite marks on fossils from the about 150-million-year-old Migut Moore quarry, located near the Colorado-Utah border. . This could mean that Allosaurus and its neighbors lived in difficult environments, and had no choice but to hunt down food remains they found.

“At that point, they’re eating every part of the skeleton, everything they put in their mouths,” says Stephanie Drumheller, a paleontologist at the University of Tennessee, Knoxville, and co-author of the new discovery. “At least under certain circumstances, these large Jurassic theropods happily ate whatever was available, including each other, and relied on bones as a food source.”

She and her team was studied over 30 years ago. , More than 2,300 fossils have been unearthed at the Mygat Moor Quarry. Usually in such places, it is rare to find bones with bite marks left by carnivorous dinosaurs and carnivores. But these scars and grooves can reveal a lot about ancient ecosystems. “Bite marks are direct evidence of interaction, a snapshot in time,” Drumheller says. “From these bite marks, we can figure out who ate whom, and specific feeding behavior.”
Some researchers believe that dinosaurs of this era had a soft-tissue diet. , bones are largely ignored, suggesting that this might explain why there are bite marks in dinosaur fossils. Not seen much at this time of year. If so, dinosaurs weren’t animals such as hyenas and crocodiles that routinely crushed and shredded bones and ate the bone marrow inside, but more like modern-day Komodo dragons that sometimes stole bones when eating the meat of their prey. There will be

New findings also suggest that predatory dinosaurs may have paid more attention to bones than previously thought. Drumheller and her colleagues found bite marks on about 29 percent of the bones from the Myghat Moore quarry, a rate “higher than you’d expect for a site like this,” she said.

Some of the bones were slightly bruised, while others were severely damaged by deep punctures and gouges. In some cases, the marked bones, especially those of herbivorous dinosaurs, corresponded to body parts that hungry dinosaurs would normally eat, such as thighs and organs. But many of the gnawed bones were from carnivorous dinosaurs, and those bones often emerged from unexpected places with little meat, such as spines and toes.

“Predators are lazy and usually prey on the easiest foods first,” says Drumheller.

Jurassic Colorado was not during It’s not an easy place to make a living and earn. The region is regularly hit by large-scale forest fires and droughts. During the dry season, food was so scarce that large predators like Allosaurus may have hunted fewer herbivorous dinosaurs. To eat, they may have relied on carcasses already plucked from other animals.

Another possibility is that garbage collection was a routine part of the lifestyle of these dinosaurs. “Perhaps what we are seeing at Mygat Moor is certainly normal, but our debt collection practices have led us to believe otherwise,” said Drumheller. It is unusual for researchers to bring back every damaged or broken bone fragment they find in the museum’s holdings. In recent years, however, paleontologists working at the Mygat Moore Quarry have been working on a batch of fossil finds. This abundance of bones may give us a better idea of ​​what the dinosaurs ate here.

Based on the size and type of bone imprints, Drumheller and colleagues could also conclude that most of the imprints were from Allosaurus’ jagged, steak-knife-like teeth. In some cases, much to the researchers’ surprise, the damaged bones belonged to Allosaurus.

“They were probably opportunistic predators, eating whatever they could find,” says Drumheller.

Cannibalism is not uncommon among modern predators, but traces of it preserved in fossils are extremely rare. Paleontologists have strong evidence of cannibalism only for two other large dinosaurs, including Tyrannosaurus rex.

The Allosaurus bones examined by Drumheller’s team show no signs of healing, nor do they show the expected signs of healing if they were injured in battle with other dinosaurs. “The unhealed tooth marks indicate that all of these bites occurred either shortly before or after death,” said paleontologist Matthew McLain of the Master’s University in Santa Clarita, California. there is,” he said. Post. “Bite marks in places that could only be reached after death indicate that some carnivorous dinosaurs did indeed cannibalize.” Tall young tyrannosaurus added: Of these tooth-marked Allosaurus bones, bitten by other Allosaurus, they are good evidence of cannibalism. “