Background Monodominant bonebeds are a relatively common occurrence for non-avian dinosaurs, and have been used to infer associative, and potentially genuinely social, behavior. Previously known assemblages are characterized as either mixed size-classes (juvenile and adult-sized specimens together) or single size-classes of individuals (only juveniles or only adult-sized individuals within the assemblage). In the latter case, it is generally unknown if these kinds of size-segregated aggregations characterize only a particular size stage or represent aggregations that happened at all size stages. Ceratopsians (“horned dinosaurs”) are known from both types of assemblages. Methods/Principal Findings Here we describe a new specimen of the ceratopsian dinosaur Protoceratops andrewsi, Granger and Gregory 1923 from Mongolia representing an aggregation of four mid-sized juvenile animals. In conjunction with existing specimens of groups of P. andrewsi that includes size-clustered aggregations of young juveniles and adult-sized specimens, this new material provides evidence for some degree of size-clustered aggregation behaviour in Protoceratops throughout ontogeny. This continuity of size-segregated (and presumably age-clustered) aggregation is previously undocumented in non-avian dinosaurs. Conclusions The juvenile group fills a key gap in the available information on aggregations in younger ceratopsians. Although we support the general hypothesis that many non-avian dinosaurs were gregarious and even social animals, we caution that evidence for sociality has been overstated and advocate a more conservative interpretation of some data of ‘sociality’ in dinosaurs.
School of Earth Sciences, University of Bristol, Bristol, United Kingdom;School of Biological & Chemical Sciences, Queen Mary University of London, London, United Kingdom;Raymond M. Alf Museum of Paleontology, Claremont, California, United States of America;Hayashibara Museum of Natural Sciences, Okayama, Japan;Hayashibara Museum of Natural Sciences, Okayama, Japan;Paleontological Center, Mongolian Academy of Sciences, Ulaanbaatar, Mongolia
Recommended Citation:
David W. E. Hone,Andrew A. Farke,Mahito Watabe,et al. A New Mass Mortality of Juvenile Protoceratops and Size-Segregated Aggregation Behaviour in Juvenile Non-Avian Dinosaurs[J]. PLOS ONE,2014-01-01,9(11)