Carnegie Museum of Natural History

One of the Four Carnegie Museums of Pittsburgh

dinosaurs in their time

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Camptosaurus aphanoecetes

skelleton of Camptosaurus aphanoecetes dinosaur in the museum
Photo Credit: Joshua Franzos for Carnegie Museum of Natural History

Camptosaurus aphanoecetes, which means “flexible lizard hiding in plain sight,” was a medium-sized plant-eating dinosaur that lived about 145–150 million years ago during the late Jurassic Period. Remains of Camptosaurus have been found in North America and, according to some paleontologists, in England as well. Although the Camptosaurus skeleton on display at Carnegie Museum of Natural History was discovered in 1922, it wasn’t studied in detail until relatively recently.

On exhibit in Pittsburgh for more than six decades, still half buried in Jurassic sandstone, the skeleton was fully removed from the rock in 2005–2006 to transform it into a three-dimensional mount. After the specimen was completely unearthed, it was discovered to show differences with fossils of the dinosaur species it was long thought to represent, Camptosaurus dispar. So, in 2008, the skeleton was established as the type, or name-bearing, specimen of the new species Camptosaurus aphanoecetes by scientists Kenneth Carpenter and
Yvonne Wilson.

This Camptosaurus skeleton was excavated by Earl Douglass and his field crew from rocks belonging to the Morrison Formation in the Carnegie Quarry at Dinosaur National Monument in Utah. Today it is on display at Carnegie Museum of Natural History.

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Stegosaurus armatus

skelleton of Stegosaurus armatus dinosaur
Photo Credit: Joshua Franzos for Carnegie Museum of Natural History

Stegosaurus armatus is one of the most recognizable dinosaurs of all. With a name that means “plated reptile,” Stegosaurus is a favorite among dinosaur enthusiasts. An herbivore, this dinosaur roamed western North America during the late Jurassic Period, between 145 and 150 million years ago.

Stegosaurus had small, simple teeth and weak jaw muscles. Scientists believe these reptiles were not effective chewers and ate vegetation that grew low to the ground, most likely ripping and swallowing most of it whole.

Growing up to 25 feet long, Stegosaurus had tall, bony plates that lined its back. While these plates probably offered protection, they were also crisscrossed by blood vessels and may have been used to regulate the animal’s body temperature or to signal to other Stegosaurus individuals. Stegosaurus also featured paired spikes on its tail, which it used for protection against large carnivorous dinosaurs such as Allosaurus. A few Allosaurus fossils have even been found with what are believed to be wounds inflicted by the tail of Stegosaurus.

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Dryosaurus altus

Dryosaurus altus skeleton
Photo Credit: Image by Josh Franzos

Unlike many herbivores of its time, Dryosaurus altus was not very large. Standing four feet high at the hips and growing up to 11 feet in length, Dryosaurus may have weighed only 200 pounds. But this bipedal dinosaur was fast. It had long, powerful hind legs that carried it through the Late Jurassic wilderness, providing its primary defense against predators.

With a name that means “tall oak tree lizard,” Dryosaurus had short front limbs and a long tail that may have been used as a counterbalance. It had a beak for cropping vegetation and was most likely an efficient chewer, with strong teeth and a hinged jaw. This hinge allowed the herbivore to slide its upper and lower jaws past one another as it chewed, an unusually advanced feeding adaptation for this time period.

One of the oldest known members of the dinosaur group Ornithopoda, Dryosaurus fossils have been found in the western United States and possibly eastern Africa (though some paleontologists think the African fossils belong instead to a close relative called Dysalotosaurus). The specimen on display at Carnegie Museum of Natural History was discovered in 1910 by Earl Douglass and his field crew in the Morrison Formation at what is now Dinosaur National Monument in Utah.

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Protoceratops andrewsi

dinosaur fossil of Protoceratops andrewsi in a museum display
Photo Credit: Image by Josh Franzos for Carnegie Museum of Natural History

Protoceratops andrewsi is a fairly small and primitive ceratopsian, or horned dinosaur. Although it lacked the horns of later species, Protoceratops had a distinct bump above its nostrils and thickened bone over its eye sockets. Like its larger and geologically younger relative Triceratops, this herbivore also had a bony neck frill that may have been used for species identification and display. With a name that means “Andrews’ early horned face,” this dinosaur reached two and one-half feet tall at the hips and grew up to six feet long. It weighed around 200 pounds and had a horn-covered beak that it used to crop plants and to defend itself.

Protoceratops was first discovered in Mongolia, and a great many specimens have since been found in that nation and in northern China. They range in size from hatchlings to full-grown adults, including one that is preserved locked in combat with an individual of Velociraptor, the predatory ‘raptor’ made famous by the Jurassic Park films.

Protoceratops thrived in Central Asia during the late Cretaceous Period, roughly 80-75 million years ago. Roughly 20 million years beforehand, a ceratopsian species that closely resembled Protoceratops is thought to have migrated from Asia to North America via a land bridge that spanned the region between what are now Siberia and Alaska. The descendants of this dinosaur eventually evolved into the huge horned ceratopsians such as Triceratops.

The Protoceratops on display at Carnegie Museum was collected by the American Museum of Natural History during an expedition to Mongolia in 1925 and obtained via an exchange in 1945.

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Celebrated fossil quarry

old black and white photo of fossil quarry at Dinosaur National Monument in Utah

The celebrated fossil quarry at what is now recognized as Dinosaur National Monument in Utah was discovered in 1909 by Carnegie Museum field collector Earl Douglass.

From 1909–1923, Douglass and his crews collected more than 350 tons (700,000 pounds) of fossils from that site alone. Several dinosaur skeletons discovered by Douglass at this quarry are featured in our core exhibition hall, Dinosaurs in Their Time.

Others grace the exhibit halls of other prominent North American museums, such as the American Museum of Natural History in New York, the Smithsonian Institution’s National Museum of Natural History in Washington, DC, the Denver Museum of Nature and Science, and the Royal Ontario Museum in Toronto.