Editing Protoceratops (section)

===Djadokhta Formation===
[[File:Protoceratops in Djadokhta.png|thumb|Restoration of a ''P. andrewsi'' group in the Djadokhta Formation]]
''Protoceratops'' is known from most localities of the [[Djadokhta Formation]] in Mongolia, which dates back to the Late Cretaceous about 71 million to 75&nbsp;million years ago, being deposited during a rapid sequence of polarity changes in the late part of the Campanian stage.<ref name=Dashzeveg2005>{{cite journal|last1=Dashzeveg|first1=D.|last2=Dingus|first2=L.|last3=Loope|first3=D. B.|last4=Swisher III|first4=C. C.|last5=Dulam|first5=T.|last6=Sweeney|first6=M. R.|date=2005|title=New Stratigraphic Subdivision, Depositional Environment, and Age Estimate for the Upper Cretaceous Djadokhta Formation, Southern Ulan Nur Basin, Mongolia|journal=American Museum Novitates|number=3498|pages=1–31|doi=10.1206/0003-0082(2005)498[0001:NSSDEA]2.0.CO;2|hdl=2246/5667|s2cid=55836458 |hdl-access=free|url=http://digitallibrary.amnh.org/bitstream/handle/2246/5667/N3498.pdf?sequence=1&isAllowed=y}}</ref> Dominant sediments at Djadokhta include dominant reddish-orange and pale orange to light gray, medium to fine-grained [[sand]]s and sandstones, caliche, and sparse [[fluvial]] (river-deposited) processes. Based on these components, the paleoenvironments of the Djadokhta Formation are interpreted as having a hot, semiarid climate with large dune fields/sand dunes and several short-lived [[water bodies]], similar to the modern [[Gobi Desert]]. It is estimated that at the end of the Campanian age and into the [[Maastrichtian]] the climate would shift to the more [[Mesic habitat|mesic]] (humid/wet) conditions seen in the [[Nemegt Formation]].<ref>{{cite book|last1=Jerzykiewicz|first1=T.|year=1997|chapter=Djadokhta Formation|editor-last1=Currie|editor-first1=P. J.|editor-last2=Padian|editor-first2=K.|title=Encyclopedia of Dinosaurs|url-access=limited|publisher=Academic Press|location=San Diego|pages=[https://archive.org/details/encyclopediadino00curr_075/page/n218 188]−191|isbn=978-0-12-226810-6|url=https://archive.org/details/encyclopediadino00curr_075}}</ref><ref name=Dingus2008>{{cite journal|last1=Dingus|first1=L.|last2=Loope|first2=D. B.|last3=Dashzeveg|first3=D.|last4=Swisher III|first4=C. C.|last5=Minjin|first5=C.|last6=Novacek|first6=M. J.|last7=Norell|first7=M. A.|date=2008|title=The Geology of Ukhaa Tolgod (Djadokhta Formation, Upper Cretaceous, Nemegt Basin, Mongolia)|journal=American Museum Novitates|number=3616|pages=1–40|doi=10.1206/442.1|hdl=2246/5916|s2cid=129735494 |hdl-access=free|url=https://core.ac.uk/download/pdf/189860633.pdf}}{{Dead link|date=June 2022 |bot=InternetArchiveBot |fix-attempted=yes }}</ref><ref name=Chinzoorig2017>{{cite journal|last1=Chinzorig|first1=T.|last2=Kobayashi|first2=Y.|last3=Tsogtbaatar|first3=K.|last4=Currie|first4=P. J.|last5=Watabe|first5=M.|last6=Barsbold|first6=R.|date=2017|title=First Ornithomimid (Theropoda, Ornithomimosauria) from the Upper Cretaceous Djadokhta Formation of Tögrögiin Shiree, Mongolia|journal=Scientific Reports|volume=7|issue=5835|page=5835 |bibcode=2017NatSR...7.5835C|doi=10.1038/s41598-017-05272-6|doi-access=free|pmc=5517598|pmid=28724887}}</ref>

The Djadokhta Formation is separated into a lower Bayn Dzak Member and upper Turgrugyin Member. ''Protoceratops'' is largely known from both members, having ''P. andrewsi'' as a dominant and representative species in the overall formation.<ref name=Dashzeveg2005/><ref name=Dingus2008/> The Bayn Dzak member (mostly the Bayn Dzak locality) has yielded the dromaeosaurids ''[[Halszkaraptor]]'' and ''Velociraptor mongoliensis'';<ref name=Norel1999>{{cite journal|last1=Norell|first1=M. A.|last2=Makovicky|first2=P. J.|date=1999|title=Important Features of the Dromaeosaurid Skeleton II: Information from Newly Collected Specimens of Velociraptor mongoliensis|journal=American Museum Novitates|number=3282|pages=1–45|hdl=2246/3025|hdl-access=free|oclc=802169086}}</ref><ref>{{cite journal|last1=Cau|first1=A.|last2=Beyrand|first2=V.|last3=Voeten|first3=D. F. A. E.|last4=Fernandez|first4=V.|last5=Tafforeau|first5=P.|last6=Stein|first6=K.|last7=Barsbold|first7=R.|last8=Tsogtbaatar|first8=K.|last9=Currie|first9=P. J.|last10=Godefroit|first10=P.|date=2017|title=Synchrotron scanning reveals amphibious ecomorphology in a new clade of bird-like dinosaurs|journal=Nature|volume=552|issue=7685|pages=395–399|bibcode=2017Natur.552..395C|doi=10.1038/nature24679|pmid=29211712|s2cid=4471941 |url=https://www.researchgate.net/publication/321609878}}</ref> oviraptorid ''[[Oviraptor]]'';<ref name=Osborn1924/> ankylosaurid ''Pinacosaurus grangeri'';<ref name=CurrieP2011/> and troodontid ''[[Saurornithoides]]''.<ref>{{cite journal|last1=Norell|first1=M. A.|last2=Makovicky|first2=P. J.|last3=Bever|first3=G. S.|last4=Balanoff|first4=A. M.|last5=Clark|first5=J. M.|last6=Barsbold|first6=R.|last7=Rowe|first7=T.|date=2009|title=A review of the Mongolian Cretaceous dinosaur Saurornithoides (Troodontidae, Theropoda)|journal=American Museum Novitates|number=3654|pages=1–63|doi=10.1206/648.1|hdl=2246/5973|hdl-access=free|url=https://www.biodiversitylibrary.org/itempdf/280747}}</ref> Ukhaa Tolgod, a highly fossiliferous locality is also included in the Bayn Dzak member.<ref name=Dingus2008/> and its dinosaur paleofauna is composed of alvarezsaurids ''[[Kol (dinosaur)|Kol]]'' and ''[[Shuvuuia]]'';<ref>{{cite journal|last1=Suzuki|first1=S.|last2=Chiappe|first2=L. M.|last3=Dyke|first3=G. J.|last4=Watabe|first4=M.|last5=Barsbold|first5=R.|last6=Tsogtbaatar|first6=K.|date=2002|title=A New Specimen of Shuvuuia deserti Chiappe et al., 1998, from the Mongolian Late Cretaceous with a Discussion of the Relationships of Alvarezsaurids to Other Theropod Dinosaurs|journal=Contributions in Science|volume=494|pages=1–18|doi=10.5962/p.226791|s2cid=135344028 |doi-access=free}}</ref><ref>{{cite journal|first1=A. H.|last1=Turner|first2=S. J.|last2=Nesbitt|first3=M. A.|last3=Norell|date=2009|title=A Large Alvarezsaurid from the Late Cretaceous of Mongolia|journal=American Museum Novitates|number=3648|pages=1–14|doi=10.1206/639.1|hdl=2246/5967|hdl-access=free|s2cid=59459861|url=https://digitallibrary.amnh.org/bitstream/handle/2246/5967/N3648.pdf?sequence=1&isAllowed=y}}</ref> ankylosaurid ''[[Minotaurasaurus]]'';<ref>{{cite journal|last1=Alicea|first1=J.|last2=Loewen|first2=M.|date=2013|title=New Minotaurasaurus material from the Djodokta Formation establishes new taxonomic and stratigraphic criteria for the taxon|journal=Journal of Vertebrate Paleontology|volume=Program and Abstracts|page=76|url=http://vertpaleo.org/Annual-Meeting/Future-Past-Meetings/MeetingPdfs/SVP-2013-merged-book-10-15-2013.aspx}}</ref> birds ''[[Apsaravis]]'' and ''[[Gobipteryx]]'';<ref>{{cite journal|last1=Chiappe|first1=L. M.|last2=Norell|first2=M. A.|last3=Clark|first3=J.|date=2001|title=A New Skull of Gobipteryx minuta (Aves: Enantiornithes) from the Cretaceous of the Gobi Desert|journal=American Museum Novitates|number=3346|pages=1–15|doi=10.1206/0003-0082(2001)346<0001:ANSOGM>2.0.CO;2|hdl=2246/2899|s2cid=51857603 |hdl-access=free|url=https://archive.org/download/newskullgobipte3346chia/newskullgobipte3346chia.pdf}}.</ref><ref>{{cite journal|last1=Clarke|first1=J. A.|last2=Norell|first2=M. A.|date=2002|title=The Morphology and Phylogenetic Position of Apsaravis ukhaana from the Late Cretaceous of Mongolia|journal=American Museum Novitates|number=3387|pages=1–46|doi=10.1206/0003-0082(2002)387<0001:TMAPPO>2.0.CO;2|hdl=2246/2876|s2cid=52971055 |hdl-access=free|url=https://digitallibrary.amnh.org/bitstream/handle/2246/2876//v2/dspace/ingest/pdfSource/nov/N3387.pdf?sequence=1&isAllowed=y}}</ref> dromaeosaurid ''[[Tsaagan]]'';<ref>{{cite journal|last1=Norell|first1=M. A.|last2=Clark|first2=J. M.|last3=Turner|first3=A. H.|last4=Makovicky|first4=P. J.|last5=Barsbold|first5=R.|last6=Rowe|first6=T.|date=2006|title=A New Dromaeosaurid Theropod from Ukhaa Tolgod (Ömnögov, Mongolia)|journal=American Museum Novitates|number=3545|pages=1–51|doi=10.1206/0003-0082(2006)3545[1:ANDTFU]2.0.CO;2|hdl=2246/5823|hdl-access=free|url=https://www.researchgate.net/publication/232678611}}</ref> oviraptorids ''[[Citipati]]'' and ''[[Khaan]]'';<ref>{{cite journal|last1=Clark|first1=J. M.|last2=Norell|first2=M. A.|last3=Barsbold|first3=R.|date=2001|title=Two new oviraptorids (Theropoda: Oviraptorosauria) from the Late Cretaceous Djadokta Formation, Ukhaa Tolgod|journal=Journal of Vertebrate Paleontology|volume=21|issue=2|pages=209–213|doi=10.1671/0272-4634(2001)021[0209:TNOTOU]2.0.CO;2|jstor=20061948|s2cid=86076568 |url=https://www.researchgate.net/publication/232685671}}</ref> troodontids ''[[Almas ukhaa|Almas]]'' and ''[[Byronosaurus]]'';<ref>{{cite journal|last1=Makovicky|first1=P. J.|last2=Norell|first2=M. A.|last3=Clark|first3=J. M.|last4=Rowe|first4=T. E.|date=2003|title=Osteology and Relationships of Byronosaurus jaffei (Theropoda: Troodontidae)|journal=American Museum Novitates|number=3402|pages=1–32|doi=10.1206/0003-0082(2003)402<0001:oarobj>2.0.co;2|hdl=2246/2828|s2cid=51824767 |hdl-access=free|url=https://digitallibrary.amnh.org/bitstream/handle/2246/2828//v2/dspace/ingest/pdfSource/nov/N3402.pdf?sequence=1&isAllowed=y}}</ref><ref>{{cite journal|last1=Pei|first1=R.|last2=Norell|first2=M. A.|last3=Barta|first3=D. E|last4=Bever|first4=G. S.|last5=Pittman|first5=M.|last6=Xu|first6=X.|date=2017|title=Osteology of a New Late Cretaceous Troodontid Specimen from Ukhaa Tolgod, Ömnögovi Aimag, Mongolia|journal=American Museum Novitates|number=3889|pages=1–47|doi=10.1206/3889.1|hdl=2246/6818|hdl-access=free|s2cid=90883541|url=https://ia903007.us.archive.org/27/items/osteologynewlat00peir/osteologynewlat00peir.pdf}}</ref> and a new, unnamed protoceratopsid closely related to ''Protoceratops''.<ref>{{cite journal|last1=Prieto-Márquez|first1=A.|last2=Garcia-Porta|first2=J.|last3=Joshi|first3=S. H.|last4=Norell|first4=M. A.|last5=Makovicky|first5=P. J.|date=2020|title=Modularity and heterochrony in the evolution of the ceratopsian dinosaur frill|journal=Ecology and Evolution|volume=10|issue=13|pages=6288–6309|doi=10.1002/ece3.6361|doi-access=free|pmc=7381594|pmid=32724514|bibcode=2020EcoEv..10.6288P }}</ref> In the Turgrugyin Member (mainly Tugriken Shireh locality), ''P. andrewsi'' shared its paleoenvironment with the bird ''[[Elsornis]]'';<ref>{{cite journal|last1=Chiappe|first1=L. M.|last2=Suzuki|first2=S.|last3=Dyke|first3=G. J.|last4=Watabe|first4=M.|last5=Tsogtbaatar|first5=K.|last6=Barsbold|first6=R.|date=2007|title=A new Enantiornithine bird from the Late Cretaceous of the Gobi desert|journal=Journal of Systematic Palaeontology|volume=5|issue=2|pages=193–208|doi=10.1017/S1477201906001969|bibcode=2007JSPal...5..193C |s2cid=85391743}}</ref> dromaeosaurids ''[[Mahakala omnogovae|Mahakala]]'' and ''Velociraptor mongoliensis'';<ref name=Norel1999/><ref>{{cite journal|last1=Turner|first1=A. H.|last2=Pol|first2=D.|last3=Clarke|first3=J. A.|last4=Erickson|first4=G. M.|last5=Norell|first5=M. A.|date=2007|title=A Basal Dromaeosaurid and Size Evolution Preceding Avian Flight|journal=Science|volume=317|issue=5843|pages=1378–1381|bibcode=2007Sci...317.1378T|doi=10.1126/science.1144066|doi-access=free|pmid=17823350}}</ref> and [[ornithomimid]] ''[[Aepyornithomimus]]''.<ref name=Chinzoorig2017/> ''P. andrewsi'' is also abundant at Udyn Sayr,<ref name=Handa2012/><ref name=Czepiński2020/> where ''[[Avimimus]]'' and ''[[Udanoceratops]]'' have been recovered.<ref>{{cite journal|last1=Kurzanov|first1=S. M.|date=1992|title=A giant protoceratopsid from the Upper Cretaceous of Mongolia|journal=Paleontological Journal|pages=81–93|language=ru}}</ref><ref>{{cite journal|last1=Watabe|first1=M.|last2=Suzuki|first2=S.|last3=Tsogtbaatar|first3=K.|date=2006|title=Geological and geographical distribution of bird-like theropod, Avimimus in Mongolia|journal =Journal of Vertebrate Paleontology|volume=26|issue=supp. 003|pages=136A−137A|doi=10.1080/02724634.2006.10010069|s2cid=220413406}}</ref>

The relatively low dinosaur paleodiversity, small body size of most dinosaurs, and [[arid]] settings of the Djadokhta Formation compared to those of the Nemegt Formation, suggest that ''Protoceratops'' and contemporaneous biota lived in a [[Stress (biology)|stressed]] paleoenvironment (physical factors that generate adverse impacts on the ecosystem).<ref name=Longriich20110/> In addition, the high occurrence of protoceratopsid fossils in arid-deposited formations indicates that these ceratopsians preferred warm environments.<ref name=Longrich2010/><ref name=Longriich20110/> Although ''P. andrewsi'' was the predominant protoceratopsid on this formation, tentative remains of ''P. hellenikorhinus'' have been reported from the Udyn Sayr and Bor Tolgoi localities, suggesting that both species co-existed. Whereas ''P. andrewsi'' is found in aeolian sediments (Bayn Dzak or Tugriken Shireh), ''P. hellenikorhinus'' is found in the aeolian-fluvial sediments. As the latter type of sediments is also found in the Bayan Mandahu Formation, it is likely that ''P. hellenikorhinus'' preferred environments combining [[Mesic habitat|humid]] and arid conditions.<ref>{{cite conference|last1=Chiba|first1=K.|last2=Ryan|first2=M. J.|last3=Saneyoshi|first3= M.|last4=Konishi|first4=S.|last5=Yamamoto|first5=Y.|last6=Mainbayar|first6=B.|last7=Tsogtbaatar|first7=K.|date= 12–16 October 2020|title=Taxonomic re-evaluation of Protoceratops (Dinosauria: Ceratopsia) specimens from Udyn Sayr, Mongolia|conference=The Society of Vertebrate Paleontology 80th Annual Meeting|url=https://vertpaleo.org/wp-content/uploads/2021/03/SVP_2020_Program-Abstracts-Volume-FINAL-for-Publishing-1.27.2021.pdf|page = 104}}</ref>