Editing Protoceratops (section)

===Predator–prey interactions===
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|image1 = Fighting dinosaurs (1).jpg
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|footer = Fossil cast of the Fighting Dinosaurs specimen (left) and life restoration of same depicting the fight (right)
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Barsbold in 1974 shortly described the [[Fighting Dinosaurs]] specimen and discussed possible scenarios. The ''Velociraptor'' has its right leg pinned under the ''Protoceratops'' body with its left sickle claw oriented into the throat region. The ''Protoceratops'' bit the right hand of the predator, implying that it was unable to escape. Barsbold suggested that both animals drowned as they fell into a [[swamp]]-like [[body of water]] or, the relatively [[quicksand]]-like bottom of a lake could have kept them together during the last moments of their fight.<ref name=Barsbolld1974>{{cite journal|last1=Barsbold|first1=R.|date=1974|title=Поединок динозавров|trans-title=Dueling dinosaurs|journal=Priroda|volume=2|pages=81–83|language=ru}}</ref>

Osmólska in 1993 proposed another two hypotheses to explain their preservation. During the death struggle, a large [[dune]] may have collapsed simultaneously burying both ''Protoceratops'' and ''Velociraptor''. Another proposal is that the ''Velociraptor'' was [[scavenging]] an already dead ''Protoceratops'' when it got buried and eventually killed by indeterminate circumstances.<ref name=Osmolska1993>{{cite journal|last1=Osmólska|first1=H.|date=1993|title=Were the Mongolian Fighting Dinosaurs really fighting?|journal=Rev. Paleobiol.|volume=7|pages=161–162}}</ref>

In 1995, David M. Unwin and colleagues cast doubt on previous explanations especially a scavenging hypothesis as there were numerous indications of a concurrent death event. For instance, the ''Protoceratops'' has a semi-erect stance and its skull is nearly horizontal, which could have not been possible if the animal was already dead. The ''Velociraptor'' has its right hand trapped within the jaws of the ''Protoceratops'' and the left one grasping the ''Protoceratops'' skull. Moreover, it lies on the floor with its feet directed to the prey's belly and throat areas, indicating that this ''Velociraptor'' was not scavenging. Unwin and colleagues examined the [[sediment]]s surrounding the specimen and suggested that the two were buried alive by a powerful [[sandstorm]]. They interpreted the interaction as the ''Protoceratops'' being grasped and dispatched with kicks delivered by the low-lying ''Velociraptor''. They also considered possible that populations of ''Velociraptor'' were aware of crouching behaviors in ''Protoceratops'' during high-energy sandstorms and used it for successful hunts.<ref name=Unwin1995>{{cite journal|last1=Unwin|first1=D. M.|last2=Perle|first2=A.|last3=Trueman|first3=C.|date=1995|title=Protoceratops and Velociraptor preserved in association: Evidence from predatory behavior in predatory dinosaurs?|journal=Journal of Vertebrate Paleontology|volume=15|issue=supp. 003|page=57A|doi=10.1080/02724634.1995.10011277}}</ref>
[[File:Fighting Dinosaurs size.png|thumb|left|Size of the Fighting Dinosaurs]]
[[Kenneth Carpenter]] in 1998 considered the Fighting Dinosaurs specimen to be conclusive evidence for theropods as active [[predator]]s and not scavengers. He suggested another scenario where the multiple [[wound]]s delivered by the ''Velociraptor'' on the ''Protoceratops'' throat had the latter animal bleeding to death. As a last effort, the ''Protoceratops'' bit the right hand of the predator and trapped it beneath its own weight, causing the eventual death and [[desiccation]] of the ''Velociraptor''. The missing limbs of the ''Protoceratops'' were afterwards taken by scavengers. Lastly, both animals were buried by sand. Given that the ''Velociraptor'' is relatively complete, Carpenter suggested that it may have been completely or partially buried by sand.<ref>{{cite journal|last1=Carpenter|first1=K.|date=1998|title=Evidence of predatory behavior by carnivorous dinosaurs|journal=Gaia|volume=15|pages=135–144|url=http://www.arca.museus.ul.pt/ArcaSite/obj/gaia/MNHNL-0000778-MG-DOC-web.PDF}}</ref>

In 2010, David Hone with team reported a new interaction between ''Velociraptor'' and ''Protoceratops'' based on [[Trace fossil|tooth marks]]. Several fossils were collected at the Gate locality of the [[Bayan Mandahu Formation]] in 2008, including teeth and body remains of protoceratopsid and [[velociraptorine]] dinosaurs. The team referred these elements to ''Protoceratops'' and ''Velociraptor'' mainly based on their abundance across the unit, although they admitted that reported remains could represent different, yet related taxa (in this case, ''[[Linheraptor]]'' instead of ''Velociraptor''). At least eight body fossils of ''Protoceratops'' present active teeth marks, which were interpreted as feeding traces. Much in contrast to the Fighting Dinosaurs specimen, the tooth marks are inferred to have been produced by the dromaeosaurid during late-stage [[Carrion|carcass]] consumption either during scavenging or following a [[Pack hunter|group kill]]. The team stated that feeding by ''Velociraptor'' upon ''Protoceratops'' was probably a relatively common occurrence in these environments, and that this ceratopsian actively formed part of the diet of ''Velociraptor''.<ref>{{cite journal|last1=Hone|first1=D.|last2=Choiniere|first2=J.|last3=Sullivan|first3=C.|last4=Xu|first4=X.|last5=Pittman|first5=M.|last6=Tan|first6=Q.|date=2010|title=New evidence for a trophic relationship between the dinosaurs Velociraptor and Protoceratops|journal=Palaeogeography, Palaeoclimatology, Palaeoecology|volume=291|issue=3–4|pages=488–492|bibcode=2010PPP...291..488H|doi=10.1016/j.palaeo.2010.03.028}}</ref>

In 2016, Barsbold re-examined the Fighting Dinosaurs specimen and found several anomalies within the ''Protoceratops'' individual: both coracoids have small bone fragments indicatives of a [[Bone fracture|breaking]] of the pectoral girdle; the right forelimb and scapulocoracoid are torn off to the left and backward relative to its [[torso]]. He concluded that the prominent displacement of pectoral elements and right forelimb was caused by an external force that tried to tear them out. Since this event likely occurred after the death of both animals or during a point where movement was not possible, and the ''Protoceratops'' is missing other body elements, Barsbold suggested that scavengers were the most likely authors. Because ''Protoceratops'' is considered to have been a [[herd]]ing animal, another hypothesis is that members of a herd tried to pull out the already buried ''Protoceratops'', causing the [[joint dislocation]] of limbs. However, Barsbold pointed out that there are no related traces within the overall specimen to support this latter interpretation. Lastly, he restored the course of the fight with the ''Protoceratops'' power-slamming the ''Velociraptor'', which used its feet claws to damage the throat and belly regions and its hand claws to grasp the herbivore's head. Before their burial, the deathmatch ended up on the ground with the ''Velociraptor'' lying on its back right under the ''Protoceratops''. After burial, either ''Protoceratops'' herd or scavengers tore off the buried ''Protoceratops'' to the left and backward, making both predator and prey to be slightly separated.<ref name=Barsbold2016>{{cite journal|last1=Barsbold|first1=R.|date=2016|title=The Fighting Dinosaurs: The position of their bodies before and after death|journal=Paleontological Journal|volume=50|issue=12|pages=1412–1417|doi=10.1134/S0031030116120042|bibcode=2016PalJ...50.1412B |s2cid=90811750 }}</ref>