Last Meal of 'Exceptionally Preserved' Armor-Plated Dinosaur That Died 110 Million Years Ago Revealed by Scientists

Researchers have revealed what a 2,800-pound armor-plated dinosaur ate for its last meal before it perished around 110 million years ago.

In 2011, miners accidentally uncovered the fossilized remains of a dinosaur specimen representing the species Borealopelta markmitchelli—a type of nodosaur—at a site near Fort McMurray in Alberta, Canada.

Following the discovery, a team of Canadian scientists from the Royal Tyrrell Museum of Palaeontology, Brandon University, and the University of Saskatchewan (USask) began investigating the extremely well-preserved specimen, whose fossilized stomach contents have survived to this day as a soccer-ball-sized mass.

"The finding of the actual preserved stomach contents from a dinosaur is extraordinarily rare, and this stomach recovered from the mummified nodosaur by the museum team is by far the best-preserved dinosaur stomach ever found to date," Jim Basinger, one of the scientists from USask, said in a statement.

"When people see this stunning fossil and are told that we know what its last meal was because its stomach was so well preserved inside the skeleton, it will almost bring the beast back to life for them, providing a glimpse of how the animal actually carried out its daily activities, where it lived, and what its preferred food was."

In a study published in the journal Royal Society Open Science, the researchers reveal that the dinosaur's last meals were composed almost entirely of ferns, providing the most detailed insight yet of the diet of large herbivores living more than 110 million years ago.

"The last meal of our dinosaur was mostly fern leaves—88 per cent chewed leaf material and seven per cent stems and twigs," David Greenwood, another author of the study from Brandon University, said in a statement.

"When we examined thin sections of the stomach contents under a microscope, we were shocked to see beautifully preserved and concentrated plant material. In marine rocks we almost never see such superb preservation of leaves, including the microscopic, spore-producing sporangia of ferns."

Analysis of the stomach contents suggested that the dinosaur was a picky eater, mostly choosing to eat certain types of ferns—known as leptosporangiates—over others that would have also been common in the animal's environment at the time, according to the study.

While previous studies into the diets of herbivorous dinosaurs has revealed evidence of seeds and twigs in the gut, they did not provide an indication of which kinds of plants the animals were eating. Paleontologists have long had to resort to speculation when it comes to determining the diet of herbivorous dinosaurs based on characteristics such as tooth and jaw shape, as well as the known availability of specific plants.

Borealopelta markmitchelli, dinosaur
Artist's illustration of the Borealopelta markmitchelli dinosaur eating ferns. © Illustration by Julius Csotonyi © Royal Tyrrell Museum of Palaeontology

"This new study changes what we know about the diet of large herbivorous dinosaurs," Royal Tyrrell Museum palaeontologist Caleb Brown said in the statement. "Our findings are also remarkable for what they can tell us about the animal's interaction with its environment, details we don't usually get just from the dinosaur skeleton."

In addition to the plant material, the authors also detected an abundance of charcoal in the stomach contents of the dinosaur, suggesting that the animal lived in an environment that was prone to regular wildfires.

"There is considerable charcoal in the stomach from burnt plant fragments, indicating that the animal was browsing in a recently burned area and was taking advantage of a recent fire and the flush of ferns that frequently emerges on a burned landscape," Greenwood said.

"This adaptation to a fire ecology is new information. Like large herbivores alive today such as moose and deer, and elephants in Africa, these nodosaurs by their feeding would have shaped the vegetation on the landscape, possibly maintaining more open areas by their grazing."

Jordan Mallon, a paleobiologist from the Canadian Museum of Nature, who was not involved in the latest study, told Newsweek that the paper's findings are significant given that it's usually hard to determine what dinosaurs ate because their food typically doesn't preserve within the stomach.

"As palaeontologists, we're often left to reason what they ate based on the shapes of their teeth, the isotopic make-up of their enamel, the construction of their skulls, and more," he said. "This latest study by Brown and colleagues is a blue moon-type event that we all wait for because it finally provides some hard data about what the armoured dinosaurs ate. I'm especially chuffed because their findings—that at least this one individual specialized on ferns—support my own published predictions. It's nice to get something right once in a while."

"I think it's important to keep in mind that these isolated finds tell us what one particular animal ate at one moment of time, and aren't necessarily representative of an animal's diet. This one [nodosaur] ended up dead, after all, so it's entirely possible that this last meal is what killed it. Maybe this dinosaur ate a poisonous fern or cycad frond."

The analysis of the stomach contents has even shed new light on the animal's death, indicating that it must have occurred shortly after the last meal.

"Plants give us a much better idea of season than animals, and they indicate that the last meal and the animal's death and burial all happened in the late spring to mid-summer," Brown said.

"Taken together, these findings enable us to make inferences about the ecology of the animal, including how selective it was in choosing which plants to eat and how it may have exploited forest fire regrowth. It will also assist in understanding of dinosaur digestion and physiology."

Sebastián Rozadilla, a paleontologist from The Bernardino Rivadavia Natural Sciences Argentine Museum, Argentina, who was also not involved in the latest study, said the paper was "special because it introduces us to something that is very beautiful in science: interdisciplinarity."

"This is thanks to the sublime mummified remains of the nodosaur Borealopelta. Just as this dinosaur seems to be suspended in eternal sleep, so is its last supper. Using different disciplines, in a fusion between vertebrate paleontology and paleobotany, researchers join forces to reveal how the place was millions of years ago when Borealopelta lived," he told Newsweek.

According to research featured in the CBC documentary Dinosaur Cold Case, the dinosaur may have drowned in a flood and its body was washed out into the vast inland sea that once cut right through the North American continent, covering the area that is now Alberta.

Once the dinosaur had sunk to the seafloor, it became coated in mud, helping to preserve it in exceptional condition for more than a hundred million years until miners accidentally uncovered the remains during work at the Suncor Millennium open pit mine around 17 miles north of Fort McMurray in April, 2011.

In fact, the renowned Borealopelta markmitchelli specimen—which has been on display at the Royal Tyrrell Museum since 2017—is considered to be the best-preserved nodosaur fossil ever found. Nodosaurs are a family of heavily-armored dinosaurs that lived between the Late Jurassic (around 163 to 145 million years ago) and Cretaceous (around 145 to 66 million years ago) periods in what is now North America, Europe, Asia, Africa, and Antarctica.

This article was updated to include additional comments from Jordan Mallon and Sebastián Rozadilla.