Photos of the Protoceratops (AMNH 6418) with a “mummified” head, from Brown & Schlaikjer (1940).
In a previous post I covered the lost Tarbosaurus with skin impressions; it turns out it isn’t the only Mongolian dinosaur to suffer this fate. A specimen of the ceratopsian Protoceratops andrewsi (AMNH 6418) similarly had possible impressions
that were destroyed [see second addendum]. It was collected at the famous Bayn Dzak (“Flaming Cliffs”) locality by the 2nd Central Asiatic Expedition in 1923. Brown and Schlaikjer (1940) later described AMNH 6418 and included photographs of it. These photos show the skull covered with what look like small scales and skin folds, reminiscent of hadrosaur “mummies”. Typical of their time, Brown and Schlaikjer only devoted a short paragraph to the integument.
“Only one specimen (Am. Mus. No. 6418) presents any suggestion of the integument. This is a nearly complete skeleton, which was found in an unusual curled up position. A thin, hard, and wrinkled layer of matrix covers a considerable portion of the skull and jaws. The wrinkling has a very skin-like appearance, and is most predominant on the left side of the head over the orbit, at the corner of the mouth just in front of the jugal, and over the side of the frill and lateral temporal opening (see plate 13). As far as can be determined, it is without any trace of skin-structure. The surface form of the original skin, however, undoubtedly influenced the form of the matrix at burial, and by the chemical action set up through its decay probably caused this thin layer of matrix surrounding the bone to become considerably indurated.”
Brown and Schlaikjer concluded that it was an encrusting layer of sediment that had been taphonomically influenced by skin decay. This is certainly a plausible interpretation, but due to the lack of thorough analysis the skin impression interpretation is just as plausible.
The skull of AMNH 6418 in its current state with the skin removed. Photo by João Vasco Leite, used with permission.
Unfortunately, recent photos courtesy of João Vasco Leite have confirmed that the potential impressions have all been prepared away. The rostrum has been reconstructed, suggesting that it too was damaged in the preparation process. It’s a shame to think of what could have been learned from this specimen. We are just left with the original photos to speculate on. Connective skin between the jugal and frill, nasal and oral tissues, and even eyelids appear to be visible. These present tantalizing subjects for paleoartists, but can never be studied due to the carelessness of past workers [see second addendum].
Bell et al. (2022) included this specimen in their list of ceratopsians with preserved integument. They hypothesized that the skin covering may have been composed of pebbly basement scales.
It turns out that only the right side of the skull and the entire rostrum were fully prepared, while most of the impressions on the left side have survived. Fortunately, they can still be scientifically studied and their true origin can be determined. The photos below were taken by Łukasz Czepiński and edited and posted on Facebook by Boban Filipović; they are reproduced here with the latter’s permission.
- Bell, P.R., Hendrickx, C., Pittman, M., & Kaye, T.G. (2022). The exquisitely preserved integument of Psittacosaurus and the scaly skin of ceratopsian dinosaurs. Communications Biology, 5, Article 809. https://doi.org/10.1038/s42003-022-03749-3
- Brown, B., & Schlaikjer, E.M. (1940). The structure and relationships of Protoceratops. Annals of the New York Academy of Sciences, 40(3), 133-266.