Borealopelta

Phylogeny: Dinosauria > Ornithischia > Genasauria > Thyreophora > Thyreophoroidea > Eurypoda > Ankylosauria > Euankylosauria > Nodosauridae > Nodosaurinae

Overview: Many ankylosaurs are only known from partial remains or bits of dermal armor, but in a few cases, some remarkably well preserved specimens are found. Perhaps the best of such remains were accidently unearthed in 2011, at an oil sands mine in northern Alberta. Workers would report the find to paleontologists, who initially suspected the remains would be those of a marine reptile, since the Clearwater Formation mostly preserves ocean-going life. However, what they found was a beautifully intact head, neck, shoulders, and torso of a nodosaurid ankylosaur – all of it preserved in three dimensions, unlike many fossils which are crushed and warped by time. Studies concluded the fossils were of a new genus, later named Borealopelta in its 2017 description. Its generic name means “northern shield”, referring to it being farther north than many other Canadian dinosaurs, as well as to its extensive armor plating. Smaller osteoderms covered the head, large spined plates sat over the neck, long spines extended from the shoulders, and rounded scutes covered the back and hips of the animal. All of these osteoderms are positioned where they would’ve been in life.

How exactly this Borealopelta specimen wound up at sea isn’t fully understood, though its carcass may’ve been washed into the sea by a river or storm. As it began to decompose, the body bloated, floating on the surface, but it eventually sank upside down into the seabed. Its back was obscured and covered by sediment, preserving it for future fossilization. Even the keratin encasing the bone cores of its spines is preserved in some places. Studies would even find traces of pigment cells on its fossilized skin, revealing the top part of its body was a dark, reddish color, while underneath it was paler. This counter-shading was itself a form of camouflage, making it harder to contrast the body from its surroundings. Even if it were detected, Borealopelta was safe from most predators, at least as an adult, though its underbelly was less protected. With a length of five to six meters, it was a decently large nodosaurid. Nodosaurids, like Borealopelta itself, tended to possess narrower jaws than those of the ankylosaurids, implying a more selective diet. No tail has been found as of yet, but as a nodosaurid, we can confidently predict it would’ve lacked one.