In this blog post, we will introduce the fascinating story of how the Borealopelta fossil was discovered in such amazing condition and reveal its scientific secrets.

The secrets of the perfectly preserved Borealopelta fossil

In 2011, miner John Funk was working in a mine in Alberta, Canada, when he discovered a strange rock. This huge rock, which appeared to have something stuck to its surface, did not look like a simple rock. Sensing that something was unusual, he immediately contacted the Royal Tyrrell Museum. Over the next six years, researchers at the museum carefully carved away the rock and excavated the fossil inside.
Finally, the fossil was revealed to be a species of nodosaur, an armored dinosaur that lived about 110 million years ago. It was a large herbivorous dinosaur, measuring about 5 meters in length and weighing 1,300 kilograms. This dinosaur was named Borealopelta markmitchelli after Mark Mitchell, the researcher who made a significant contribution to the fossilization process.
However, there was another reason why this fossil attracted worldwide attention. It was because its state of preservation was the most complete of any dinosaur fossil ever found. Not only was the head intact, but the bony plates extending from the neck to the hips were also almost completely preserved, and even the keratin tissue, which is rarely found in dinosaur fossils, remained intact.
In particular, the large, pointed bone plates in the shoulder area accounted for about one-third of the bones, with the rest covered by thick keratin tissue. This appears to be similar in structure to the horns of modern goats, bison, and chameleons. It is believed that Borealopelta also had a similar appearance.

Even the color of the dinosaur was restored

In 2017, Dr. Brown and his research team discovered a substance called benzothiazole in the skin tissue on the surface of the fossil. This substance is related to pheomelanin, which contains sulfur, and exhibits a reddish color. Based on this, it was analyzed that Borealopelta’s body was reddish brown in color.
Furthermore, the researchers suggested that it may have had a “countershading” pattern, with a dark red color on the upper body and a gradually lighter color on the lower body. This color distribution provides a camouflage effect, helping to hide the body from predators, and is a feature seen in many modern herbivores. Borealopelta is believed to have developed these colors to protect itself from large predators such as Acrocanthosaurus.

A land dinosaur found in the sea

So why was such a perfectly preserved land dinosaur fossil found in marine strata? The area where the Borealopelta fossils were excavated was submerged in the sea during the Cretaceous period. Researchers believe that the dinosaurs died near the coast, and their bodies were washed ashore and sank to the seabed, where they were fossilized.
However, what further confused scientists was the fact that the fossils were found upside down. Furthermore, it is noteworthy that about 70% of the armored dinosaur fossils found in marine strata are upside down.
Various hypotheses have been proposed to explain this phenomenon. In 1928, Dr. Ops argued that when armored dinosaurs slipped and fell from coastal hills, their bodies turned upside down and they were unable to right themselves, dying in that position. However, this theory was quickly refuted because it was based on the assumption that dinosaurs were excessively slow.
Another hypothesis was that carnivorous dinosaurs turned the armored dinosaurs upside down and left them in that position so they could eat their stomachs first. However, out of dozens of fossils, only one showed teeth marks from a carnivorous dinosaur.

The most plausible “expansion and flotation” hypothesis

In 1984, Dr. Carpenter proposed a new hypothesis using the example of armadillos.
After death, armadillos often decay and become filled with gas, causing their abdomens to swell and their bodies to naturally turn upside down. He explained that armored dinosaurs would have turned upside down in the same way.
However, in 2018, Dr. Jordan Malone refuted this hypothesis. He analyzed several dead armadillo carcasses and found that their positions varied, which he used to disprove the hypothesis.
Instead, Dr. Mallon proposed the “expansion and buoyancy hypothesis.” According to this hypothesis, after the dinosaur died, intestinal bacteria caused gas to accumulate in the abdomen, shifting the center of buoyancy and causing the carcass to easily flip over. If it floats upside down in the water and sinks to the seabed, it is more likely to fossilize in that position.

“Ironstone” formation enabled preservation

During the decomposition process, gases released from the carcasses reacted with iron ions in the water to form a hard “ironstone” mineral that enveloped the carcasses. This ironstone slowed down the decomposition of the carcasses, and the mud on the seabed blocked oxygen, resulting in the creation of the most complete dinosaur fossils in existence today.
The perfection was also confirmed by the contents of the stomach. In 2020, Dr. Brown identified the remains of plants that Borealopelta had eaten in its stomach. Under a microscope, various plant tissues, mainly ferns, were clearly visible. Analysis showed that 88% of the stomach contents were ferns, and 5.7% were burnt plant tissue, or charcoal.
This is interpreted as evidence that wildfires were frequent in the area at the time, and it has been suggested that Borealopelta may have preferred to eat the new shoots that sprouted after the fires. It is known that oxygen concentrations were higher in the Late Jurassic than they are today, and wildfires were frequent.

Fossils, a time machine that brings back 100 million years

The Borealopelta fossil, created by a combination of chance and scientific inevitability, takes us back 100 million years. We now have a precise understanding of what this dinosaur looked like, what color it was, what it ate, and what kind of environment it lived in. It is a tool for time travel that is more realistic than any time machine. Fossils themselves can be said to be windows to the past.