Researchers look at a dinosaur in its remarkably preserved face

Researchers look at a dinosaur in its remarkably preserved face

Researchers look at a dinosaur in its remarkably preserved face

Royal Tyrrell Museum of Paleontology

Borealopelta mitchelli found its way back to sunlight in 2017, millions of years after it died. This armored dinosaur is so beautifully preserved that we can see what it looked like in life. Almost the entire animal – the skin, the armor that covers its skin, the spines along its side, most of its body and feet, even its face – survived the fossilization. According to dr. Donald Henderson, curator of dinosaurs at the Royal Tyrrell Museum, it’s a find of one in a billion.

In addition to its remarkable preservation, this dinosaur is an important key to understanding aspects of early Cretaceous ecology, showing how this species may have lived in its environment. Since his remains were discovered, scientists have studied his anatomy, his armor, and even what he ate in his final days, uncovering new and unexpected insights into an animal that went extinct about 100 million years ago.

Down by the sea

Borealopelta is a nodosaurus, a type of four-legged ankylosaurus with a straight tail instead of a club tail. The 2011 find in an ancient marine environment was a surprise given that the animal was terrestrial.

A terrestrial megaherbivore preserved in an ancient seabed is not as unusual as one might think. A number of other ankylosaurs have been preserved this way, albeit not as well Borealopelta. Scientists suspect that the carcass was carried from a river to the sea during a flood; it may have floated upside down on the surface for a few days before sinking into the depths of the ocean.

It would have been kept on the surface by what is referred to as “bloat-and-float”, as the buildup of post-mortem gases would keep it afloat. Modeling done by Henderson indicates that his heavy armor would have rolled him onto his back, a position he suspects would have prevented ocean predators from scavenging his carcass.

Once the gases that kept it afloat had been expelled, Borealopelta sank to the ocean floor and landed on its back.

“We can tell it went into water deeper than 50 meters because it’s preserved with a certain mineral called glauconite, which is a green phosphate mineral. And it only forms at lower temperatures in water deeper than 50 meters,” explains Dr. Henderson .

He also told Ars that this environment probably discouraged cleanup as well, saying, “It was probably a region where [long-necked] plesiosaurs and big fish didn’t like to go. It was too cold and too dark, and [there was] nothing to eat. And there were very few trace fossils in the sediments around it. So there wasn’t much worms and crustaceans and bivalves and things in it to further digest it. It was just a nice set of seafloor conditions with very low biological activity that led to that preservation.

Unfulfilled expectations

But none of this was known when the animal was discovered. While it’s not entirely uncommon to find dinosaur remains in marine environments, it’s not very common either. Henderson and Darren Tanke, also of the Royal Tyrrell Museum, walked onto the site expecting to unearth an ancient marine reptile.

The two had been discussing fossil discoveries in other open-pit mines in the province. However, this was their first visit to Suncor, a mine in northeastern Alberta, Canada. Everything about this mine is huge. Huge machines are in constant motion, scooping rocks, sand and gravel from the surrounding cliffs while other equipment clears it away, all with the goal of exposing the deeper oil sands for fuel.

“It’s just incredible, the scale of the place,” said Dr. Henderson. “And it goes on 24 hours a day, 365 days a year.”

Despite the pace of operations, one shovel operator, Shawn Funk, noticed something after extracting a large chunk from the cliff. It was thanks to him and several people within Suncor that operations in that area ceased and the Royal Tyrrell was notified.

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