Dinosaurs A to Z
Ceratopsidae

Pachyrhinosaurus canadensis PAK-ee-RIE-noh-SOR-us

"Thick-nosed lizard"

Pachyrhinosaurus silhouette
You 1.8 m (5.9 ft) tall
Pachyrhinosaurus 7 m (23 ft) long
as long as 4 people standing fingertip to fingertip
silhouette · Andrew Farke (CC-BY) via PhyloPic
Length
7 m (23 ft) — About 7 m long, ~4 tonnes — no nose horn, but a thick bony pad instead.
Period
Late Cretaceous (73–69 Mya)
Place
North America · Alberta, Canada · Alaska
Food
Herbivore — Tough plants — beak and tooth batteries similar to other ceratopsians.
Clade
Ceratopsidae Dinosauria Ornithischia Cerapoda Marginocephalia Big horned ceratopsians of the Late Cretaceous.

A horned dinosaur that traded its nose horn for a massive slab of bone.

Pachyrhinosaurus reconstruction by Connor Ashbridge
Reconstruction · Connor Ashbridge (CC-BY)

Pachyrhinosaurus did not have a nose horn. Where other ceratopsians grew one, Pachyrhinosaurus grew a thick bony pad called a boss — possibly the base of a keratin horn that didn’t fossilize, or a pad for head-shoving contests with rivals. It lived as far north as Alaska, surviving long polar winters that most dinosaurs didn’t experience.

More about Pachyrhinosaurus

Discovery

Named by Charles M. Sternberg · 1950 · Alberta, Canada

Charles M. Sternberg discovered the first examples in Alberta, Canada, in 1946, and the genus was named in 1950. Many fossils were not available for study until the 1980s, which led to a relatively recent rise in interest.

The name comes from Ancient Greek and means roughly "thick nose lizard": thick (pachy), nose (rhino), and lizard (saurus).

Portrait of Charles M. Sternberg
Charles M. Sternberg He discovered the first known examples of Pachyrhinosaurus in Alberta and named the genus.
How did two big plant-eaters share the same Alaskan landscape?
In the Prince Creek Formation, P. perotorum lived alongside Edmontosaurus, a hadrosaurA 'duck-billed' dinosaur with batteries of grinding teeth; often crested.. The text describes niche partitioning between them: Edmontosaurus favoured lowland deltas while Pachyrhinosaurus preferred more upland environments.
Why did interest in Pachyrhinosaurus surge so long after it was named?
Although the genus was named in 1950, a great number of its fossils were not available for study until the 1980s. That delayed access is what drove the relatively recent increase of interest in the animal.

What we know

  • Thick bony nose boss instead of a horn — unique among ceratopsians.
  • Found as far north as Alaska, suggesting tolerance of polar conditions.
  • Bonebeds preserve hundreds of individuals — large migrating herds are possible.
  • Frill carried small horns and bumps, but no big spikes like Styracosaurus.

What we guess

  • Whether the boss supported a keratin pad, a horn, or just a fleshy cushion.
  • Whether Alaska populations migrated south for winter or stayed.
  • Whether the boss was used in head-pushing contests like a modern musk ox.