Editing Protoceratops (section)

===Feeding===
In 1955, paleontologist [[Georg Haas (paleontologist)|Georg Haas]] examined the overall skull shape of ''Protoceratops'' and attempted to reconstruct its [[Muscles of mastication|jaw musculature]]. He suggested that the large [[neck frill]] was likely an attachment site for masticatory muscles. Such placement of the muscles may have helped to anchor the lower jaws, useful for feeding.<ref>{{cite journal |last1=Haas|first1=G.|date=1955|title=The Jaw Musculature in Protoceratops and in Other Ceratopsians|journal=American Museum Novitates|number=1729|pages=1–24|hdl=2246/2444|url=https://digitallibrary.amnh.org/bitstream/handle/2246/2444//v2/dspace/ingest/pdfSource/nov/N1729.pdf?sequence=1&isAllowed=y}}</ref> Yannicke Dauphin and colleagues in 1988 described the [[Tooth enamel|enamel]] microstructure of ''Protoceratops'', observing a non-prismatic outer layer. They concluded that enamel shape does not relate to the [[Diet (nutrition)|diet]] or function of the [[teeth]] as most animals do not necessarily use teeth to process food. The maxillary teeth of ceratopsians were usually packed into a [[dental battery]] that formed vertical shearing blades which probably chopped the [[leaves]]. This feeding method was likely more efficient in protoceratopsids as the enamel surface of ''Protoceratops'' was coarsely-textured and the tips of the micro-serrations developed on the basis of the teeth, probably helping to crumble vegetation. Based on their respective peg-like shape and reduced microornamentation, Dauphin and colleagues suggested that the premaxillary teeth of ''Protoceratops'' had no specific function.<ref name=Yannicke1988>{{cite journal|last1=Dauphin|first1=Y.|last2=Jaeger|first2=J.-J.|last3=Osmólska|first3=H.|date=1988|title=Enamel microstructure of ceratopsian teeth (Reptilia, Archosauria)|journal=Geobios|volume=21|issue=3|pages=319–327|doi=10.1016/S0016-6995(88)80056-1|bibcode=1988Geobi..21..319D }}</ref>

In 1991, the paleontologist [[Gregory S. Paul]] stated that contrary to the popular view of ornithischians as obligate [[herbivore]]s, some groups may have been opportunistic [[Carnivore|meat-eater]]s, including the members of Ceratopsidae and Protoceratopsidae. He pointed out that their prominent parrot-like beaks and shearing teeth along with powerful muscles on the jaws suggest an omnivore diet instead, much like pigs, [[Warthog|hog]]s, [[boar]]s and [[entelodont]]s. Such scenario indicates a possible competition with the more predatory [[theropods]] over [[Carrion|carcasses]], however, as the animal tissue ingestion was occasional and not the bulk of their diet, the [[Energy flow (ecology)|energy flow]] in [[ecosystem]]s was relatively simple.<ref>{{cite journal|last1=Paul|first1=G. S.|date=1991|title=The many myths, some old, some new, of dinosaurology|journal=Modern Geology|volume=16|pages=69–99|url=http://gspauldino.com/Myths.pdf}}</ref> You Hailu and Peter Dodson in 2004 suggested that the premaxillary teeth of ''Protoceratops'' may have been useful for selective cropping and feeding.<ref name=Hailu2004>{{cite book|last1=Hailu|first1=Y.|last2=Dodson|first2=P.|year=2004|chapter=Basal Ceratopsia|chapter-url=https://content.ucpress.edu/pages/2601001/2601001.ch22.pdf|editor-last1=Weishampel|editor-first1=D. B.|editor-last2=Dodson|editor-first2=P.|editor-last3=Osmólska|editor-first3=H.|title=The Dinosauria|edition=2nd|page=493|publisher=University of California Press|isbn=9780520941434}}</ref>

In 2009, Kyo Tanque and team suggested that basal ceratopsians, such as protoceratopsids, were most likely low [[Browsing (herbivory)|browsers]] due to their relatively small body size. This low-browsing method would have allowed to feed on [[foliage]] and fruits within range, and large basal ceratopsians may have consumed tougher [[seed]]s or plant material not available to smaller basal ceratopsians.<ref>{{cite journal|last1=Tanoue|first1=K.|last2=Grandstaff|first2=B. S.|last3=You|first3=H.-L.|last4=Dodson|first4=P.|date=2009|title=Jaw Mechanics in Basal Ceratopsia (Ornithischia, Dinosauria)|journal=The Anatomical Record|volume=292|issue=9|pages=1352–1369|doi=10.1002/ar.20979|doi-access=free|pmid=19711460}}</ref>

[[David J. Button]] and [[Lindsay E. Zanno]] in 2019 performed a large phylogenetic analysis based on skull [[Biomechanics|biomechanical]] characters—provided by 160 [[Mesozoic]] dinosaur species—to analyze the multiple emergences of herbivory among non-avian dinosaurs. Their results found that herbivorous dinosaurs mainly followed two distinct modes of feeding, either processing food in the gut—characterized by relatively gracile skulls and low [[Bite force quotient|bite forces]]—or the mouth, which was characterized by features associated with extensive processing such as high bite forces and robust jaw musculature. Ceratopsians (including protoceratopsids), along with ''[[Euoplocephalus]]'', ''[[Hungarosaurus]]'', [[parkosaurid]], [[ornithopod]] and [[heterodontosaurine]] dinosaurs, were found to be in the former category, indicating that ''Protoceratops'' and relatives had strong bite forces and relied mostly on its jaws to process food.<ref>{{cite journal|last1=Button|first1=D. J.|last2=Zanno|first2=L. E.|date=2019|title=Repeated Evolution of Divergent Modes of Herbivory in Non-avian Dinosaurs|journal=Current Biology|volume=30|issue=1|pages=158–168|doi=10.1016/j.cub.2019.10.050|doi-access=free|pmid=31813611|s2cid=208652510|url=https://www.cell.com/current-biology/pdf/S0960-9822(19)31390-9.pdf}}</ref>