April 4, 2022 Scott Kraus

Pachyrhinosaurus was a Cretaceous Ceratopsid

Pachyrhinosaurus was a late Cretaceous Ceratopsid that lived 68-73 million years ago. Its name is Greek for “thick-nosed lizard”. Thick noses and elaborate, bony frills are distinguishing characteristics in the Pachyrhinosaurus genus, which was one of the last to roam the Earth before the mass extinction.

Quick Facts

About Pachyrhinosaurus

Pachyrhinosaurus was a genus of Ceratopsids that appeared on the scene late in the Cretaceous Era. Pachyrhinosaurus and related Ceratopsids such as Psittacosaurus, Chasmosaurus, Protoceratops, and Triceratops were one of the last groups of dinosaurs to evolve so their rise to prominence occurred in the last era of dinosaurs—the Cretaceous. Although numerous specimens were discovered in the 1940’s and 50’s, the area in which the first collection of the genus was discovered, the Scabby Butte dig site in Alberta, wasn’t open for study until the 1980’s.

What Did Pachyrhinosaurus Look Like?

Pachyrhinosaurus was a member of the Ceratopsia suborder, which means it had all of the characteristics that were prevalent in the suborder—a bony neck frill, parrot-like beak, horned face and thick body. Early Ceratopsids were smaller, bipedal dinosaurs, but as they evolved they turned into heavy, quadrupedal animals like Pachyrhinosaurus.

Skulls are often the best-preserved bones of Ceratopsids and are used to differentiate between genus and species. The skulls of Pachyrhinosaurus have a bony, a spiked neck frill, a beak, horns, and a thick protruding lump of bone on top of the snout that was accompanied by a small horn in some species. The large nasal bones are the most important anatomical part in regards to identification. It is used to distinguish between the three species of Pachyrhinosaurus and paleontologists have formed theories about the purpose of this feature. Some believe it is a sexual characteristics, but most scientists think it was used as a battering ram in competition for females during the mating season.

A bone-on-bone collision involving two Pachyrhinosaurus had to have sent loud cracks out across the land. The thick, heavy skulls were supported by the rhinoceros-like body of the Pachyrhinosaurus. These dinosaurs could weigh as much as four tons and charge at speeds of up to 20 miles per hour. Pachyrhinosaurus’s speed was limited, though, due to the short length of its legs. Despite having an almost non-existent tail, this dinosaur measured 20 to 25 feet in length. This is about twice the length of most modern-day rhinoceros, which the Pachyrhinosaurus is often compared to.

What did Pachyrhinosaurus eat?

Pachyrhinosaurus was an herbivore. Like the rest of the Ceratopsids, Pachyrhinosaurus used a beak to shear prehistoric plants and numerous strong teeth to grind the tough material. This made it possible for this dinosaur to eat a wide variety of plants. Pachyrhinosaurus was probably a constant eater due to its size. Some of the suggested plants that this dinosaur could have fed on are: conifers (redwoods, yews, pines, and cypress trees), cycads, ferns, and flowering plants, which first appeared on Earth about 140 million years ago during the Jurassic period. Conifers were the most ubiquitous food source during the Mesozoic era when the dinosaurs lived, so it is thought that these plants made up the greatest percentage of their food supply.

How did Pachyrhinosaurus Move and Migrate?

All three species of Pachyrhinosaurus were quadrupedal dinosaurs that walked in the same manner as modern-day rhinoceros. Some paleontologists theorize that Pachyrhinosaurus would charge at predators like a rhinoceros are known to do in order to defend itself. Running at speeds of close to 20 miles per hour while weighing four tons, Pachyrhinosaurus could have dealt a blow similar to that of a large truck moving at the same speed. Also known to travel in herds, strength in numbers might have been another survival tactic.

It is believed that Pachyrhinosaurus traveled in packs because a massive bone bed was discovered by Al Lakusta in 1972. In this massive dinosaur graveyard, fourteen skulls and over 3,000 individual bones were found. These bones were studied and the ages of these dinosaurs ranged from juveniles to mature adults. This indicated not only that the Pachyrhinosaurus species traveled in herds, but also took care of their young.

Where did Pachyrhinosaurus live?

Pachyrhinosaurus inhabited western North America near the Alaska and Alberta areas. The close proximity of fossil remains suggests that each Pachyrhinosaurus species had a small habitat. Paleontologists think that coastal areas during the Cretaceous period were covered with herds of Pachyrhinosaurus and Edmontosaurus—a duck-billed herbivore.

The Discovery of Pachyrhinosaurus

In 1946 a massive Ceratopsid skull was unearthed in Alberta, Canada. Four years later the discoverer, Charles M. Sternberg, named the species Pachyrhinosaurus. The species was found in the Scabby Butte site, which was first established in the 1880’s. This location wasn’t appreciated for its fossil collection, though, until dinosaur hunters made numerous discoveries in the late 1940’s and 50’s.

Since the initial discovery, more than 12 partial skulls and various bones have been found in Alberta and Alaska. These remains are thought to be from three different species, although the latest discovery, P. perotorum, hasn’t been officially documented as a separate species at the moment. The bones that are thought to be a new species were discovered in the Prince Creek Formation in Alaska, thus broadening the habitat of the genus. This species is believed to have lived between 70-69 million years ago, which makes it the last Pachyrhinosaurus species to roam the Earth. P. Canadensis supposedly lived between 71.5-71 million years ago and the first species of the genus, P. lakustai, is thought to have lived from 73.5-72.5 million years ago.

Pachyrhinosaurus and Birds

Pachyrhinosaurus was a massive dinosaur that weighed more than an elephant and draws rhinoceros comparisons due to the “rhino” in its name. So what does this behemoth have to do with birds?

Moving up the taxonomic ladder, you will notice that Pachyrhinosaurus is in the suborder Ceratopsia. Go one step further and you reach the order Ornithischia. This is where the bird comparison comes in. Ornithischia is a combination of two Greek words—“ornitheos” meaning “of a bird” and “ischion” meaning “hip joint”. So every dinosaur within the Ornithischia order has bird-like hips. The pubis was set parallel to the vertebral column in the same way that a modern-day bird pubis does. Although this didn’t give Ceratopids the ability to fly, it may explain how some members of the suborder shifted between bipedal and quadrupedal movement.

The Importance of Pachyrhinosaurus

Pachyrhinosaurus has been most important to the field of paleontology in the last half-century. Since it was discovered a relatively short time ago in 1946, research hasn’t been exhausted on the species. In fact, most Pachyrhinosaurus remains weren’t available for study until the 1980’s, which fueled research when the remains were finally made available. While some dinosaurs had been studied thoroughly for 100 years or more, new discoveries were being made at an amazing rate during Pachyrhinosaurus’ first few years of research.

Another vital effect of Pachyrhinosaurus’s discovery was the attention that the Scabby Butte site received upon news of its contents. Originally founded in the late 1800’s, the site produced little excitement for paleontologists until dozens of Pachyrhinosaurus were dug up in the 1940’s and 50’s. With these finds, researchers flocked to the site in hopes of uncovering the next new dinosaur species. It has been reported that the University of Calgary has considered reopening this important site for university-level students to dig around in. So don’t be surprised if the Scabby Butte dig site is in the news someday because of another discovery or the discovery of many more Pachyrhinosaurus specimens.