Appendicular skeleton of Protoceratops andrewsi (Dinosauria, Ornithischia): comparative morphology, ontogenetic changes, and the implications for non-ceratopsid ceratopsian locomotion

Justyna Słowiak; Victor S Tereshchenko; Łucja Fostowicz-Frelik

doi:10.7717/peerj.7324

Appendicular skeleton of Protoceratops andrewsi (Dinosauria, Ornithischia): comparative morphology, ontogenetic changes, and the implications for non-ceratopsid ceratopsian locomotion

PeerJ. 2019 Jul 22:7:e7324. doi: 10.7717/peerj.7324. eCollection 2019.

Authors

Justyna Słowiak¹, Victor S Tereshchenko², Łucja Fostowicz-Frelik^{1

3}

Affiliations

¹ Department of Evolutionary Paleobiology, Institute of Paleobiology, Polish Academy of Sciences, Warsaw, Poland.
² Laboratory of Paleoherpetology, Paleontological Institute, Russian Academy of Sciences, Moscow, Russia.
³ Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China.

Abstract

Protoceratops andrewsi is a well-known ceratopsian dinosaur from the Djadokhta Formation (Upper Cretaceous, Mongolia). Since the 1920s, numerous skeletons of different ontogenetic stages from hatchlings to adults, including fully articulated specimens, have been discovered, but the postcranial anatomy of Protoceratops has not been studied in detail. A new, mostly articulated subadult individual provides an excellent opportunity for us to comprehensively describe the anatomy of the limb skeleton, to compare to other ceratopsian dinosaurs, and to study the ontogenetic and intraspecific variation in this species. New data provided by the specimen shed light on the lifestyle of P. andrewsi. The young subadult individuals present an array of morphological characters intermediate between the bipedal Psittacosaurus and fully quadrupedal adult P. andrewsi. We compare these observations with a broad range of non-ceratopsid Neoceratopsia (of various locomotor adaptations) and Psittacosauridae (obligate bipeds), which gives us insight into the evolution of the skeletal characters informative for the postural change in ceratopsian dinosaurs.

Keywords: Ceratopsian dinosaurs; Limb morphology; Locomotion; Ontogeny; Ornithischia; Stance.

Grants and funding

Financial support for this study comes from Russian Foundation for Basic Research grant No. 16-05-00408 to Victor S. Tereshchenko and the University of Warsaw student grants to Justyna Słowiak. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.