and had increased mobility—a mobility that stars to decrease towards the high neural spines—, which suggest that the tail could be largely raised from its base. It is likely that Protoceratops raised its tail as a signal (display) or females could use this method during egg laying in order to expand and relax the cloaca. In 2016 Hone and team indicated that the tail of Protoceratops, particularly the mid region with elevated neural spines, could have been used in display to impress potential mates and/or for species recognition. The tail may have been related with structures like the frill for displaying behavior. Kim with team in 2019 cited the elongated tail spines as well-suited for swimming. They indicated that both Bagaceratops and Protoceratops may have used their tails in a similar fashion during similar situations, such as swimming, given how similar their postcranial skeletons were. The team also suggested that a swimming adaptation could have been useful to avoid aquatic predators, such as crocodylomorphs. Social behavior Tomasz Jerzykiewiczz in 1993 reported several monospecific (containing only one dominant species) death assemblages of Protoceratops from the Bayan Mandahu and Djadokhta formations. A group of five medium-sized and adult Protoceratops was observed at the Bayan Mandahu locality. Individuals within this assemblage were lying on their bellies with their heads facing upwards, side by side parallel-aligned, and inclined about 21 degrees from the horizontal plane. Two other groups were found at the Tugriken Shireh locality; one group containing six individuals and another group of about 12 skeletons. In 2014 David W. E. Hone and colleagues reported and described two blocks containing death assemblages of P. andrewsi from Tugriken Shireh. The first block (MPC-D 100/526) comprises four juvenile individuals in close proximity with their heads pointing upwards, and the second block (MPC-D 100/534) is composed of two sub-adults with a horizontal orientation. Based on previous assemblages and the two blocks, the team determined that Protoceratops was a social dinosaur that formed herds throughout its life and such herds would have varied in composition, with some including adults, sub-adults, siblings from a single nest or local members of a herd joining shortly after hatching. However, as the group could have loss members by predation or other factors, the remnants individuals would aggregate into larger groups to increase their survival. Hone and colleagues in particular suggested that juveniles would aggregate primarily as a defense against predators and