Protoceratops - Discovery and Species

Discovery and Species

Photographer J.B. Shackelford discovered the first specimen of Protoceratops in the Gobi desert, (Gansu, Inner Mongolia), as part of a 1922 American expedition looking for human ancestors. No early human fossils were found, but the expedition, led by Roy Chapman Andrews, collected many specimens of the Protoceratops genus, along with fossil skeletons of theropods Velociraptor, Oviraptor, and ceratopsid Psittacosaurus.

Walter Granger and W.K. Gregory formally described the type species, P. andrewsi in 1923, the specific name in honor of Andrews. The fossils hail from the Djadochta Formation and date from the Campanian stage of the Upper Cretaceous (dating to between 75 and 71 million years ago). Researchers immediately noted the importance of the Protoceratops finds, and the genus was hailed as the "long-sought ancestor of Triceratops". The fossils were in an excellent state of preservation, with even the sclerotic rings (delicate occular bones) preserved in some specimens.

In 1971, a fossil was found that captured a Velociraptor mongoliensis clutched around a Protoceratops andrewsi in Mongolia. It is believed that they died simultaneously, while fighting, when they were either surprised by a sand storm or buried when a sand dune collapsed on top of them.

In 1975, Polish paleontologists Teresa Maryanska and Halszka Osmólska described a second species of Protoceratops, also from the Campanian stage of Mongolia, which they named P. kozlowskii. However, the fossils consisted of incomplete juvenile remains, and are now considered synonymous with Bagaceratops rozhdestvenskyi.

In 2001, a second valid species, P. hellenikorhinus, was named from the Bayan Mandahu Formation in Inner Mongolia, China and also dates from the Campanian stage of the Upper Cretaceous. It was notably larger than P. andrewsi, had a slightly different frill, and had more robust jugal horns. The arch of bone over its nostrils had two small nasal horns, and there were no teeth at the front of the snout.

In 2011, a specimen of Protoceratops first uncovered in 1965 was found to be preserved with its own footprint. It is the first example of a dinosaur to be preserved with footprints.