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Pachyrhinosaurus

The Pachyrhinosaurus was a genus of quadrupedal dinosaur from the Late Cretaceous period that lived in what is now the continent of North America. These huge, herbivorous creatures were characterized by their keratinous nasal horns that they probably used for defensive purposes.

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Scientific Classification

Kingdom Animalia
Phylum Chordata
Clade Dinosauria
Order †Ornithischia
Family †Ceratopsidae
Subfamily †Centrosaurinae
Clade †Pachyrostra
Genus Pachyrhinosaurus
Species P. canadensis (type species) †P. lakustaiP. perotorum

Quick Facts

Pronunciation pack-EE-rye-NO-sore-US (meaning, thick-nosed lizard)
Geological Period Late Cretaceous Period; 75 to 69 million years ago
Size About 26 feet (8 meters) in length
Height 10 feet (3 meters)
Weight About 4 tons
Average Lifespan Probably around 45 years
Location/Distribution & Habitat Watered-flooded plains with marshes and swamps subject to cool to cold winters, especially in and around present-day Alaska and Alberta
Climate/Environment Regions having cool temperatures
Diet Herbivorous
Breeding Type (Reproduction) Oviparous (egg-laying)
Locomotion Quadruped
Speed Approximately 20 mph

History and Discovery

The first fossils and skeletal remains of the Pachyrhinosaurus were actually discovered back in 1880, though didn’t  get the attention they deserved. It was not until the late 1940s that they could manage to do so, and eventually the type species was established in 1950.

The most important excavation related to the prehistoric animal was the discovery of the Pipestone Creek bone bed in the late 1980s, the first specimen from which was originally discovered by Al Lakusta in 1972.)

The entire discovery yielded almost 3,500 bones, as also, 14 skulls of the Pachyrhinosaurus, representing individuals of all ages, from full-grown adults to babies, juveniles and the young ones.

Physical Description

The skulls of the enormous pachyrhinosaurus bore massive, flattened bosses with a large one over the nose and a smaller one each over the eyes. The nasal boss in the creature is thought to have been used in head-pushing or other kinds of combats against other members.

However, these bosses were not present in all the specimens, which might be an indication of sexual dimorphism between the male and the female, or indicate that such a structure might differ with age.

Puncture wounds found on the pachyrhinosaurus’ face and frills might suggest that they used their horns for combating against other pachyrhinosaurus, locking horns together while head-butting, pushing and twisting against the opponent.

Behavior & Diet

They were herbivorous and possessed strong cheek teeth that helped them chew tough, fibrous plants. The discoveries suggested that the ceratopsians like Pachyrhinosaurus used to move in herds in order to forage for food in the forests.

The pachyrhinosaurus were large animals and probably needed to change pastures periodically. This is not merely to find food, but was possibly a behavioral adaptation as well for protection against large predators like the contemporary Albertosaurus.

Interesting Facts

  • The individuals discovered from the Pipestone Creek bone bed were named P. lakustai after the paleontologist Al Lakusta, who first discovered it.

Published on April 20th 2019 by under Reptiles.
Article was last reviewed on 16th September 2019.

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