Researchers were amazed to see that the fossil wasn’t flattened by the millions of years of rock and sediment pressing down on it.
Instead, a combination of factors led to the exceptional 3D fossilization of the newly identified species, known as B. markmitchelli.
Soon after its death, the 18-foot-long (5.5 meters) was swept out into an ancient, inland seaway that stretched from the Gulf of Mexico to the Arctic Ocean.
Once there, the dinosaur drifted away from any predators on land, such as carnivorous dinosaurs, and from marine scavengers, such as freshwater crocodilians.
“It sank out in deep water, where there was not much in the way of animal life [because it was] too cold and dark, so not much in the way of scavengers.”
The 3,000-lb. (1,360 kilograms) nodosaur landed on its back on the seabed with a gigantic thump, leaving an impact crater where the remains sank into deep ooze on the seabed.