Researchers in Calgary have discovered a massive dinosaur skull in Alberta that dates back nearly 70 million years.

Paleontologists at the University of Calgary first discovered a strange, bumpy rock during a routine fossil search in Drumheller, a town within the badlands of east-central Alberta.

Upon further inspection, the research team realized that the large rock was actually the skull of a pachyrhinosaurs, a large horned dinosaur that roamed regions of present-day Alberta and Alaska.

The four-legged herbivores measured over six metres in length and had bumps with large horns and frills extending behind its neck. Scientists say the biological features were most likely used for mating and fighting other animals.

Darla Zelenitsky, lead researcher of the project, says finding a fully-intact skull of this size is extremely uncommon.

“It is very rare to find such a complete skull specimen of this size and type in the region,” Zelenitsky said in statement on the university website.

“Based on our preliminary estimates, the dinosaur’s head would have been well over two metres long and was likely of a mature or older individual. The skull of this animal has an enormous bony structure over the snout that would have made for a very strange looking individual.”

Zelenitsky’s team removed five to six tons of rock to extract the skull and have spent the past four months carefully removing remnants of rock encasing the skull.

Researchers are not sure whether the new skull is a new species of dinosaur and say they will be conducting tests on the bone to determine its origin.

“The nature of this discovery will certainly add to our understanding of the biology of pachyrhinosaurs,” Zelenitsky said.

The research team plans to resume their search for more bones at the site in the next coming months.