Pachyrhinosaurus

Pachyrhinosaurus was a robust horned dinosaur that inhabited subarctic forests and coastal floodplains of North America during the Late Cretaceous period. Measuring up to eight metres in length and weighing several tonnes, it rivalled large modern elephants in stature. Instead of pointed horns, it developed a huge, textured bony mass known as a boss on its snout, likely covered by a tough keratinous sheath in life. Its neck frill bore intricate small horns and spikes that varied considerably between its three recognized species. Abundant fossil deposits from Alberta and Alaska indicate that Pachyrhinosaurus lived in social herds and endured challenging seasonal polar climates.

Instead of a nasal horn, it had a massive bony boss used for head-butting or displays.

Where and when

Pachyrhinosaurus lived in the Late Cretaceous, from 73.5 to 69 million years ago (Campanian-Maastrichtian age). Its remains come from Canada and United States, in the Horseshoe Canyon Formation.

The numbers

Length 6.8 m (estimates run from 5.5 to 8 m). Mass about 2.8 t. Hip height about 2.2 m. That is 4 human-lengths, or 0.61 of a double-decker bus. These are estimates from near-complete skeleton; fields marked estimated by the site are length, mass, hip height.

Compare Pachyrhinosaurus with a bus Place on the timeline