Protoceratops

Protoceratops is one of the most frequently collected non-avian dinosaurs. With hundreds of specimens found in Mongolian and Chinese sites, researchers have an excellent record of its growth and behaviour. It is classified as one of the most basal "true" ceratopsians within the group Coronosauria. While it possessed a well-developed beak and frill, it lacked the large horns and complex frill openings seen in later ceratopsids.

This sheep-sized dinosaur moved on four legs and featured a deeply hooked beak. Its parietal-squamosal frill was moderately developed and solid, unlike the windowed frills of its descendants. Small bumps appeared on its skull where larger horns would eventually evolve in later species. It had a heavy tail and sturdy limbs. While skin impressions are rare, recent reports of quill-like structures in Protoceratops—similar to those found on Psittacosaurus—suggest that early ceratopsians may have had filamentous integument.

Two species are currently recognised: the Mongolian type species P. andrewsi and P. hellenikorhinus, a larger variety from China named in 2001.

The genus is most famous for the Fighting Dinosaurs specimen (MPC-D 100/25). This fossil preserves a Protoceratops andrewsi and a Velociraptor mongoliensis locked in a lethal struggle. The Velociraptor's sickle claw is embedded in the herbivore's neck, while the Protoceratops has clamped its beak onto the predator's arm. Both animals were likely buried instantly by a collapsing sand dune.

Nesting habits are well-documented for this genus. A nest containing 15 hatchlings (Fastovsky et al. 2011) suggests that juveniles stayed together in creches, which implies parental care. In the past, many eggs in the region were misattributed to Oviraptor, the "egg thief," but later finds showed those eggs contained Oviraptor embryos. This has left the actual appearance of Protoceratops eggs uncertain. Some researchers, including Dodson (1976), have proposed sexual dimorphism in their frills, though this remains a point of contention.

Analysis of tooth wear indicates that Protoceratops browsed on tough, low-lying plants. Its diet likely included cycads and other desert-scrub vegetation typical of its arid environment.

• Fighting Dinosaurs (MPC-D 100/25) — Mongolian Academy of Sciences, Ulaanbaatar.
• AMNH 6418 — Granger & Gregory's holotype, American Museum of Natural History.
• Protoceratops creche (MPC-D 100/530) — Mongolian Academy of Sciences; 15 juveniles in single nest.
• Multiple growth-series specimens at AMNH, Mongolian Academy of Sciences, and Polish-Mongolian collections.

Sexual dimorphism — proposed by some workers (Dodson 1976) and contested by others. Quill-like integument — recent reports suggest at least some keratinous filaments in basal ceratopsians, but extent in Protoceratops itself is debated. Mythological influence — speculation that Protoceratops skulls in the Mongolian Gobi may have inspired the griffin myths of antiquity (Mayor 2000) is colourful but unprovable.

Protoceratops is famous primarily for the Fighting Dinosaurs fossil, which has been displayed at multiple international exhibitions. The genus has also featured in Walking with Dinosaurs, Dinosaur Train, and countless dinosaur reference books.

• ceratopsia
• triceratops
• styracosaurus
• centrosaurus
• velociraptor

• Brown, B., & Schlaikjer, E. M. (1940). The structure and relationships of Protoceratops. Annals of the New York Academy of Sciences, 40, 133–266.
• Dodson, P. (1976). Quantitative aspects of relative growth and sexual dimorphism in Protoceratops. Journal of Paleontology, 50, 929–940.
• Fastovsky, D. E., et al. (2011). A nest of Protoceratops andrewsi (Dinosauria, Ornithischia). Journal of Paleontology, 85, 1035–1041.
• Mayor, A. (2000). The First Fossil Hunters: Paleontology in Greek and Roman Times. Princeton University Press.