1. Parts of the Protoceratops are missing, which has been seen as evidence of scavenging by other animals.

2. Protoceratops had large orbits (the holes for its eyes), which measured around 50 millimeters in diameter.

3. Described by Walter W. Granger and W.K. Gregory in 1923, Protoceratops was initially believed to be an ancestor of the North American ceratopsians.

4. The "Fighting Dinosaurs" specimen, found in 1971, preserves a Velociraptor mongoliensis and Protoceratops andrewsi in combat and provides direct evidence of predatory behavior.

5. No early human fossils were found, but the expedition, led by Roy Chapman Andrews, collected many specimens of the genus Protoceratops, along with fossil skeletons of theropods Velociraptor, Oviraptor, and ceratopsian Psittacosaurus.