The dinosaur’s body wall did eventually rupture. The carcass then drifted down to the seabed in water that was at least 164 feet deep. Few fossils from burrowing species exist at that spot, suggesting low-oxygen conditions with little biological activity. There, the carcass remained undisturbed until Funk’s fateful day.
The animal’s thick hide, which aided preservation of the remains, still retains organic material, such as pigments. These biomolecules show that B. markmitchelli had reddish-brown skin that was darker at the top and lighter on the animal’s underside. This light-dark combination is common in animals alive today and is known as countershading.
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Co-author Jakob Vinther of the University of Bristol explained that countershading helps animals to blend into their landscapes, camouflaging their 3D forms. The dinosaur lived in a dry and open environment where the ground and vegetation exhibited earthen tones of brown, yellow, and red. Its reddish-brown hues strengthened the camouflage effect.
It was thought that few predators dared to take on husky armored dinosaurs, but B. markmitchelli evolved more for defense than offense. Brown and Henderson suspect that Acrocanthosaurus, a gigantic meat-loving dinosaur that measured around 38 feet long and weighed about 6.8 tons, hunted the armored dinosaur.
“The best anti-predatory defense that Borealopelta had would have been avoiding detection in the first place, and then looking like an unappetizing meal — by being covered in bony armor,” Brown said.