Fossil Friday #7 - Borealopelta

A lot of the time, palaeontologists have to work with small fragmental puzzles in order to build a bigger picture of an organism. Many species of ancient life have been described based on minimal evidence, such as a few teeth or a fragmented femur. This is the case with most findings, as large impressive specimens that are mostly seen in museums are unfortunately the minority. This only makes larger fossils of complete or near-complete specimens all the more exciting. Examples of these larger near-complete specimens include some of the most iconic museum specimens in the world, such as Sue the Tyrannosaurus rex or Dippy the Diplodocus carnegii. There is no doubt that these, amongst others, are some of the most impressive specimens in the world and have inspired millions of people worldwide. In my opinion, however, one of the most impressive near-complete dinosaur specimens in the world was named in 2017 and belongs to Borealopelta markmitchelli.

Holotype specimen of Borealopelta markmitchelli.

The first, and to date, only Borealopelta was discovered in 2011 by Shawn Funk, a miner in Alberta, Canada, who came across the specimen by accident, as is the case with many large significant finds. After only two days of the initial discovery, Donald Henderson and Darren Tanke from the Royal Tyrrell Museum of Palaeontology were invited to the mine to examine the specimen. Before the significance of the find was fully realised, Henderson identified it as an Ankylosaurid, which in itself seemed out of place, as the only previous fossils in this area had belonged to marine reptiles, suggesting this Borealopelta may have been swept out to sea after its death, which may have been part of the reason why it had preserved so well. It took 14 days for a team from the museum to fully excavate the specimen, and then a further 6 years to carefully prepare the fossil. Rather wholesomely, Borealopelta markmitchelli was named after its preparator, Mark Mitchell, paying homage to the extremely skilled and precise work that was required to get this incredible specimen ready for research and display (Brown et al, 2017; Greshko, 2021)

Thanks to its preservation, conclusions have been drawn about Borealopelta that are usually not able to be observed in other dinosaur genera, especially from just one specimen. It has been found that it had camouflage colouration, suggesting it was preyed upon in Cretaceous Alberta, its stomach contents contain evidence of ferns and traces of charcoal, suggesting that the area that it got its last meal from may have experienced a recent wildfire (Brown et al, 2017) The size of the ferns in the stomach content are able to give an idea of the time of year that the animal died, as they are thought to have been eaten in the early summer months. The most likely hypothesis on how this specimen may have died is that it was swept out to sea whilst walking along the coast, eventually drowning and sinking to the sea floor and becoming buried upside-down. This would explain its location and the immaculate preservation which would have required very specific conditions to happen (Brown et al, 2020).

Borealopelta was a member of the Nodosauridae clade, a group of dinosaurs that had become very widespread and successful in the Cretaceous period, particularly across North America and Europe. It had the unmistakable Ankylosaurian morphology, with a long tail and osteoderms spanning the length of the body. It had two particularly long spikes on either shoulder, a feature which may have been used both in self-defence and for courtship (Greshko, 2017).

Life reconstruction of Borealopelta markmitchelli (Royal Tyrell Museum of Palaeontology, 2017).

To date, it is rather well-regarded that this Borealopelta specimen is the most well-preserved dinosaur ever discovered. It highlights how much we can learn from one specimen, given the exceptional preservation, and its journey from the ground to the museum display highlights the skilled work and talented people that are required to bring these amazing fossils into the public eye.

References

Brown, C.M. et al. (2017) “An exceptionally preserved three-dimensional armoured dinosaur reveals insights into colouration and Cretaceous predator-prey dynamics,” Current Biology, 27(16). Available at: https://doi.org/10.1016/j.cub.2017.06.071.

Brown, C.M. et al. (2020) “Dietary palaeoecology of an early cretaceous armoured dinosaur (Ornithischia; Nodosauridae) based on floral analysis of stomach contents,” Royal Society Open Science, 7(6), p. 200305. Available at: https://doi.org/10.1098/rsos.200305.

Greshko, M. (2021) This is the best dinosaur fossil of its kind ever found, Magazine. National Geographic. Available at: https://www.nationalgeographic.com/magazine/article/dinosaur-nodosaur-fossil-discovery (Accessed: March 9, 2023).