"Sleeping" dinosaur fossil so well preserved it still sports skin and scales
It takes plenty of imagination to interpret what dinosaurs looked like and how they behaved, since all we usually have are dusty old bones squashed flat. Occasionally new insights will come from other tissues, like feathers or pickled brains, but now Canadian palaeontologists have described one of the most intact fossils ever found, which almost looks like it could wake up any minute. The specimen's skin and stomach contents have been preserved, giving new clues to its diet and camouflage.
The 110 million-year-old fossil is a new species of nodosaur, stout herbivorous animals built like a tank and weighing up to 2,800 lb (1,270 kg). It was first uncovered in 2011 at the Suncor Millennium Mine in Alberta, Canada, an area that used to be an inland sea and, as such, is rich in remains of marine reptiles like plesiosaurs. This is the first time a land-dwelling dinosaur has been dug up there, and palaeontologists from the Royal Tyrrell Museum were called in to retrieve the specimen.
"Finding the remains of an armored dinosaur that was washed far out to sea was huge surprise," says Donald Henderson, the museum's Curator of Dinosaurs. "The fact that it was so well preserved was an even bigger surprise."
Back at the museum, technician Mark Mitchell spent 7,000 hours over five-and-a-half years carefully chipping away the surrounding rock. That dedication earned him the honor of having the new species named after him: Borealopelta markmitchelli.
The specimen is stunning: 18 ft (5.5 m) long, its scaly armor is all intact, and it's been preserved in its original shape, unlike most fossils that are squashed flat by the immense pressure of the rock above them.
"This nodosaur is truly remarkable in that it is completely covered in preserved scaly skin, yet is also preserved in three dimensions, retaining the original shape of the animal," says Caleb Brown, a scientist at the Royal Tyrrell Museum. "The result is that the animal looks almost the same today as it did back in the Early Cretaceous. You don't need to use much imagination to reconstruct it; if you just squint your eyes a bit, you could almost believe it was sleeping ... It will go down in science history as one of the most beautiful and best preserved dinosaur specimens – the Mona Lisa of dinosaurs."
That unprecedented preservation is giving scientists new opportunities to piece together the ancient world the animal lived in. The organic compounds in its scales are intact enough that the researchers were able to use chemical analysis techniques to determine the pigment pattern of its skin. The creature was reddish-brown and "countershaded," meaning it had a light-colored belly and darker back.
As an effective form of camouflage, this pattern is common in prey animals today, and while it has turned up in other dinosaurs before, it surprised the team that a creature this big and well-armored would need to bother with the technique. They might not look particularly appetizing, but the find suggests that predatory dinosaurs were still hunting nodosaurs regularly enough for them to evolve this extra line of defense.
"Strong predation on a massive, heavily-armored dinosaur illustrates just how dangerous the dinosaur predators of the Cretaceous must have been," says Brown.
The nodosaur no doubt holds plenty of other answers, and researchers are now studying the preserved contents of its stomach to learn more about its diet.
Borealopelta markmitchelli is currently on display to the public at the Royal Tyrrell Museum in Alberta, and the research was published in the journal Current Biology.