In Hand Museum - Protoceratops

This small (by dinosaur standards), Late Cretaceous plant-eater, grew up to 2 meters long (6 feet), but only stood to the height of a medium sized dog. The fossils discovered by the American Museum of Natural History expeditions revealed some of our first clues about dinosaur behavior and a wealth of skeletal material. Scientific analysis of the many excavated specimens shows animals in all stages of development from very young to old and provides one of the most complete pictures of any dinosaur yet found.

Discovery
Between 1922 and 1930, Roy Chapman Andrews led five expeditions for the American Museum of Natural History to the wilds of the Gobi Desert in Mongolia. This colorful naturalist and explorer (and perhaps the model for Indiana Jones) was looking for fossils of early man, but instead found extraordinary dinosaurs. Beneath the "flaming cliffs" of Bayn-Dzak, Mongolia, he found the skeletons of one of the oldest horned dinosaurs, Protoceratops as well as those of Oviraptor.

Taxonomy
The dramatic discovery of Protoceratops insured its fame and popularity for many years. In spite of this renown and its distinctive appearance, Protoceratopsfalls onto a confusing branch of the ornithiscian dinosaur family tree. Ornithiscians are generally divided into three large groups: Thyreophora, Ornithopoda, and the Marginocephalia. While membership within each group is fairly well established, how these three groups relate to one another is still a topic of lively discussion among paleontologists.

Marginocephalians are all distinguished by some sort of bony frill or border at the back of the skull. All ceratopsians and pachycephalosaurs have this trait to a greater or lesser degree. The ceratopsian dinosaurs split from the pachycephalosaurs at the next level of distinction. This large and diverse group of plant-eaters include, not only Protoceratops and Triceratops, but also Psittacosaurus. The Protoceratops skull illustrates some of the traits that set ceratopsians apart: a narrow beak; flaring cheeks; a vaulted palate at the front of their mouth; and extended jugals.

The next level down on the taxonomic chart splits Psittacosaurus into its own group, leaving all other ceratopsians in a group known as Neoceratopsia. Look at the skull one more time. You'll notice the extended frill at the back of the head. This along with its quadrupedal stance makes it a neoceratopsian. With one last step we can distinguish Protoceratops from its more advanced cousins. When compared to Triceratops and its relatives, Protoceratops has a much smaller frill, smaller nostrils, and no horns at all.

The fossil record of the neoceratopsians is one of the best we have. Complete skeletons have been found and significant studies completed. The many Mongolian skull fossils of Protoceratops show distinguishing characteristics that allow us to identify males and females. Males had larger, more erect frills and a more prominent bump on the snout than females.

Anatomy

Protoceratops andrewsi