Another Pachyrhinosaurus bonebed, on the Wapiti River south of Beaverlodge in northwestern Alberta, was worked briefly by staff of the Royal Tyrrell Museum in the late 1980s but is now worked annually for a couple weeks each summer (since 2006) by the University of Alberta. Material from this site appears referable to Pachyrhinosaurus canadensis. In 1974, Grande Prairie, Alberta science teacher Al Lakusta found a large bonebed along Pipestone Creek in Alberta. When the area was finally excavated between 1986 and 1989 by staff and volunteers of the Royal Tyrrell Museum of Palaeontology, paleontologists discovered an amazingly large and dense selection of bones—up to 100 per square meter, with a total of 3,500 bones and 14 skulls. This was apparently the site of a mass mortality, perhaps a failed attempt to cross a river during a flood. Found amongst the fossils were the skeletons of four distinct age groups ranging from juveniles to full-grown dinosaurs, indicating that the Pachyrhinosaurus cared for their young. The adult skulls had both convex and concave bosses as well as unicorn-style horns on the parietal bone just behind their eyes. The concave boss types might be related to erosion only and not reflect male/female differences. In 2008, a detailed monograph describing the skull of the Pipestone Creek pachyrhinosaur, and penned by Philip J. Currie, Wann Langston Jr., and Darren Tanke, classified the specimen as a second species of Pachyrhinosaurus, named P. lakustai after its discoverer. In 2013, Fiorillo et al. described a new specimen, an incomplete nasal bone attributable to Pachyrhinosaurus perotorum which was collected from the Kikak-Tegoseak Quarry on the Colville River in Alaska. Fiorillo et al. named this unique northern Alaskan species after the Texas oil billionaire and benefactor, Ross Perot. This bone, designated DMNH 21460 belongs to an immature individual. This discovery expands the known age profile of this dinosaur genus from this particular site. The specimen has nasal ornamentation that is dorsally enlarged, representing an intermediate stage of growth. Of note, the authors pointed out that the posterior part of the nasal shows evidence for "a degree of integument complexity not previously recognized in other species" of Pachyrhinosaurus. It was determined that the dorsal surface of the nasal boss bore a thick, cornified pad and sheath. Description Size estimates for the largest Pachyrhinosaurus species, P. canadensis indicate lengths of and a weight of . The other species, P. lakustai and P.