Pachyrhinosaurus (Pack-ee-rine-oh-sore-us), the “thick-nosed lizard” is a genus of ceratopsian dinosaur from the Late Cretaceous of North America. The species in front of you, P. lakustai, hails specifically from Western Canada. This large herbivore is most famous for its unique facial ornament, known as a boss. Even in the age of the dinosaurs, some parts of our planet got quite cold! In Pachyrhinosaurus, we see a variety of bone growth rates that suggest this animal was endothermic (warm-blooded) and grew faster in the warm seasons than in the cold seasons, much like modern animals adapted to endure harsh winters. The species Pachyrhinosaurus perotorum is known from Alaska, making it the northernmost ceratopsid dinosaur. Pachyrhinosaurus lakustai is known from the Wapiti Formation in Canada, which yields fossils from the Late Cretaceous. These same rocks also hold fossils of Albertosaurus, Edmontosaurus, a dromaeosaur, and more. How we view the lives of dinosaurs like Pachyrhinosaurus is sure to change in the coming decades, because there are many questions fossils have yet to answer. Did these animals migrate? What other dinosaurs lived alongside them? What did they look like? How did they survive cold winters? There are numerous theories regarding these questions, but time will tell if any are supported or rejected by the newest fossil evidence.