Editing Protoceratops (section)

===Eggs and nests===

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|footer = Life restoration from 1927 and model of ''Protoceratops'' eggs based on the ''Oviraptor'' [[nest]] AMNH 6508. This nest was originally thought to represent ''Protoceratops'' eggs
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As part of the Third Central Asiatic Expedition of 1923, Andrews and team discovered the holotype specimen of ''[[Oviraptor]]'' in association with some of the first known fossilized dinosaur eggs (nest AMNH 6508), in the Djadokhta Formation. Each egg was elongated and hard-shelled, and due to the proximity and high abundance of ''Protoceratops'' in the [[Geological formation|formation]], these eggs were believed at the time to belong to this dinosaur. This resulted in the interpretation of the contemporary ''Oviraptor'' as an egg predatory animal, an interpretation also reflected in its generic name.<ref>{{cite journal|last1=Osborn|first1=H. F.|date=1924|title=The discovery of an unknown continent|journal=Natural History|volume=24|issue=2|pages=133–149}}</ref><ref name=Osborn1924/> In [[1975 in paleontology|1975]], the Chinese paleontologist [[Zhao Zikui]] named the new [[oogenera]] ''[[Elongatoolithus]]'' and ''[[Macroolithus]]'', including them in a new [[oofamily]]: the [[Elongatoolithidae]]. As the name implies, they represent elongated dinosaur eggs, including some of referred ones to ''Protoceratops''.<ref>{{cite journal |last1=Zhao|first1=Z. K.|date=1975|title=The microstructures of the dinosaurian eggshells of Nanxiong Basin, Guandong province. On the classification of dinosaur eggs|journal=Vertebrata PalAsiatica|volume=13|issue=2|pages=105–117|language=Chinese|url=http://www.ivpp.cas.cn/cbw/gjzdwxb/xbwzxz/200905/W020090813377364004471.pdf}}</ref>

In 1994 the Russian paleontologist Konstantin E. Mikhailov named the new oogenus ''[[Protoceratopsidovum]]'' from the [[Barun Goyot Formation|Barun Goyot]] and Djadokhta formations, with the type species ''P. sincerum'' and additional ''P. fluxuosum'' and ''P. minimum''. This [[ootaxon]] was firmly stated as belonging to protoceratopsid dinosaurs since they were the predominant dinosaurs where the eggs were found and some skeletons of ''Protoceratops'' were found in close proximity to ''Protoceratopsidovum'' eggs. More specifically, Mikhailov stated that ''P. sincerum'' and ''P. minimum'' were laid by ''Protoceratops'', and ''P. fluxuosum'' by ''Breviceratops''.<ref>{{cite journal|last1=Mikhailov|first1=K. E.|date=1994|title=Theropod and protoceratopsian dinosaur eggs from the Cretaceous of Mongolia and Kazakhstan|journal=Paleontological Journal|volume=28|issue=2|pages=101–120|url=https://www.researchgate.net/publication/285873142}}</ref>
[[File:Citipatibcn4.JPG|thumb|Oviraptorid embryo MPC-D 100/971, a specimen that shed light on the identity of elongatoolithid eggs]]
However, also during 1994, Norell and colleagues reported and briefly described a fossilized [[theropod]] [[embryo]] inside an egg (MPC-D 100/971) from the Djadokhta Formation. They identified this embryo as an [[oviraptorid]] dinosaur and the eggshell, upon close examination, turned out be that of elongatoolithid eggs and thereby the oofamily Elongatoolithidae was concluded to represent the eggs of oviraptorids. This find proved that the nest AMNH 6508 belonged to ''Oviraptor'' and rather than an egg-thief, the holotype was actually a mature individual that perished brooding the eggs.<ref name=Norell1994>{{cite journal|last1=Norell|first1=M. A.|last2=Clark|first2=J. M.|last3=Dashzeveg|first3=D.|last4=Barsbold|first4=R.|last5=Chiappe|first5=L. M.|last6=Davidson|first6=A. R.|last7=McKenna|first7=M. C.|last8=Altangerel|first8=P.|last9=Novacek|first9=M. J.|date=1994|title=A theropod dinosaur embryo and the affinities of the Flaming Cliffs Dinosaur eggs|journal=Science|volume=266|issue=5186|pages=779–782|bibcode=1994Sci...266..779N|doi=10.1126/science.266.5186.779|pmid=17730398|jstor=2885545|s2cid=22333224 |url=https://www.researchgate.net/publication/6110932}}</ref> Moreover, [[phylogenetic analyses]] published in 2008 by Darla K. Zelenitsky and François Therrien have shown that ''Protoceratopsidovum'' represents the eggs of a [[maniraptora]]n more derived than oviraptorids and not ''Protoceratops''.<ref>{{cite journal|last1=Zelenitsky|first1=D. K.|last2=Therrien|first2=F.|date=2008|title=Phylogenetic analysis of reproductive traits of maniraptoran theropods and its implications for egg parataxonomy|journal=Palaeontology|volume=51|issue=4|pages=807–816|doi=10.1111/J.1475-4983.2008.00770.x|bibcode=2008Palgy..51..807Z |s2cid=84859809 |doi-access=}}</ref> The description of the eggshell of ''Protoceratopsidovum'' has further confirmed that they in fact belong to a maniraptoran, possibly [[deinonychosaur]] taxon.<ref>{{cite journal|last1=Choi|first1=S.|last2=Barta|first2=D. E.|last3=Moreno-Azanza|first3=M.|last4=Kim|first4=N-H.|last5=Shaw|first5=C. A.|last6=Varricchio|first6=D. J.|date=2022|title=Microstructural description of the maniraptoran egg Protoceratopsidovum|journal=Papers in Palaeontology|volume=8|issue=2|pages=e1430|doi=10.1002/spp2.1430|bibcode=2022PPal....8E1430C |s2cid=248337010 }}</ref>

Nevertheless, in 2011 an authentic nest of ''Protoceratops'' was reported and described by David E. Fastovsky and colleagues. The nest (MPC-D 100/530) containing 15 articulated juveniles was collected from the Tugriken Shireh locality of the Djadokhta Formation during the work of Mongolian-Japanese paleontological expeditions.<ref name=Fastovsky2011/> Gregory M. Erickson and team in 2017 reported an embryo-bearing egg clutch (MPC-D 100/1021) of ''Protoceratops'' from the also fossiliferous Ukhaa Tolgod locality, discovered during paleontological expeditions of the American Museum of Natural History and [[Mongolian Academy of Sciences]]. This clutch comprises at least 12 eggs and embryos with only 6 embryos preserving nearly complete skeletons.<ref name=Erickson2017/> Norell with colleagues in 2020 examined fossilized remains around the eggs of this clutch which indicate a soft-shelled composition.<ref name=Norell2020S/>