Wikipedia

Macroolithus

Macroolithusis anoogenus(fossil-egg genus) ofdinosaur eggbelonging to theoofamilyElongatoolithidae.Thetype oospecies,M. rugustus,was originally described under the now-defunct oogenus nameOolithes.Three other oospecies are known:M. yaotunensis,M. mutabilis,andM. lashuyuanensis.They are relatively large, elongated eggs with a two-layered eggshell. Their nests consist of large, concentric rings of paired eggs. There is evidence of blue-green pigmentation in its shell, which may have helped camouflage the nests.

Macroolithus
Temporal range:Late Cretaceous
A pair ofMacroolithus yaotunensiseggs
Egg fossil classificationEdit this classification
Basic shell type: Ornithoid
Morphotype: Ornithoid-ratite
Oofamily: †Elongatoolithidae
Oogenus: †Macroolithus
Zhao, 1975
Type oospecies
†Oolithes rugustus
Young, 1965
Oospecies
  • M. rugustus(Young, 1965)
  • M. yaotunensisZhao, 1975
  • M. mutabilisMikhailov, 1994
  • M. lashuyuanensisFanget al.,2009

Macroolithuseggs have been found containingoviraptoriddinosaurembryosresemblingHeyuannia.Multiple other associations between oviraptorid and elongatoolithids (including other eggs containing embryos, parents brooding on nests, and a pair of shelledMacroolithus-like eggs preserved within an oviraptorid's pelvis) confirm that the parent ofMacroolithuswas an oviraptorid.

It is found inUpper Cretaceousformations of central and eastern Asia; fossils have been found in Mongolia, Kazakhstan and China. In the Nanxiong formation in Southern China,Macroolithusfossils range up to and possibly over theCretaceous-Tertiary boundary,which is traditionally assumed to mark the extinction of the non-aviandinosaurs. Some paleontologists have interpreted the record of dinosaur eggs at this formation as supporting a gradual extinction event, rather than a sudden cataclysmic event. However, other paleontologists believe that these interpretations are merely based on artifacts of erosion and redeposition in the earlyPaleogene.

Description

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A pair ofMacroolithuseggs

Macroolithuseggs are characterized by large size, measuring 16 to 21 cm (6.3 to 8.3 in) long, and by their particularly coarse ornamentation.[1][2]Their microstructure is not well defined in the literature,[1]but generally follows the typical elongatoolithid pattern:[2]The eggshell is arranged into two structural layers (the mammillary layer and the continuous layer). The continuous layer forms the outer part of the eggshell; its eggshell units are fused together so that the layer appears to be a continuum. The inner layer, known as the mammillary, or cone, layer is made up of cone-shaped structures that form the base of the eggshell units.[1]InMacroolithus,the continuous layer is two to three times thicker than the mammillary layer.[1][2]The eggs have great diversity of pore structure. Since gas conductance is related to the pore size and density this could imply that the eggs were laid in variable environments.[1]

Oospecies

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Four oospecies ofMacroolithusare currently recognized:

  • M. rugustus– thetype oospecies,these eggs are found inNanxiongandJiangxiin south China; it is also common in theNemegt FormationofMongoliaand theManrakskaya SvitainKazakhstan.[3][4]It ranges in size from 16.5 to 18 cm (6.5 to 7.1 in) long by 7.5 to 8.5 cm (3.0 to 3.3 in) across. Its eggshell is 0.8 to 1.7 mm (0.031 to 0.067 in) thick, about 1/4 of which is the mammillary layer.[5]The outer surface is covered with irregular chains of nodes (ramotuberculate ornamentation) around the outer center of the egg, transitioning to a more pitted, netlike pattern (sagenotuberculate) at the ends.[6][7]
  • M. yaotunensisis native toHenanand toNanxiong.[8][5]It has similar microstructure and ornamentation toM. rugustus,but can be distinguished by being slightly larger (17.5 to 21 cm (6.9 to 8.3 in) long) and having a thicker shell (1.4 to 1.9 mm (0.055 to 0.075 in)).[1][2]Also unlikeM. rugustus,M. yaotunensisshows a wavy boundary between its mammillary layer and its continuous layer.[5]
Size of twoMacroolithusoospecies
  • M. mutabilis– this Mongolian oospecies is known from several eggshell fragments. The fragments range from 1.3 to 2.0 mm (0.051 to 0.079 in) thick, slightly thicker thanM. rugustus.When complete, the egg probably measured over 17 cm (6.7 in). It is unique for what Mikhailov called "aberrational" features: several fragments have slitlike pore canals and lack ornamentation.[2]
  • M. lashuyuanensis– this oospecies is based on an eggshell fragment found in theNanxiong BasinofGuangdong.With a thickness of 2.3 to 2.7 mm (0.091 to 0.106 in), its eggshell is the thickest amongMacroolithusoospecies. It is furthermore distinguished by having a dark, dense band near the top of its continuous layer and a gradual transition between the continuous and mammilary layers.[9]

Coloration

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Some specimens ofM. yaotunensispreserve traces of the reddish brown pigmentprotoporphyrinand the blue-green pigmentbiliverdin,the same pigments used in the eggs of many modern birds. The eggs were most likely an intense blue-green color, as shown by the predominance of biliverdin in the shell. The purpose of the coloration is uncertain, but in modern birds it can serve as coloration or as a post-mating sexual signal. Colored eggs are also correlated with active paternal care in modern birds, lending further support to the hypothesis that oviraptorid males cared for their eggs.[10]

Names and etymology

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The nameMacroolithusis derived from the Greek rootsmacro-(meaning "large" )[11]andoolithus(meaning "stone egg" ), the conventional suffix for oogenus names.[12]Its Chinese name (Cự hình đảnJùxíng dàn) similarly translates to "giant egg".[5]The oospecific epiphetsyaotunensis(Chinese:Diêu truânyáotún) andlashuyuanensis(Chinese:Tịch thụ viênLàshùyuán) honor the localities where those oospecies were originally discovered (the Yaotun[5]and Lashuyuan[9]districts of Guangdong, respectively), affixing the Latin suffix-ensisto denote the place of origin;[13]the namemutabilisis Latin for changeable.[2]When he named"Oolithes" rugustus,Yang (1965) did not give the etymology ofrugustus,but the Chinese form (Thô bìcūpí) translates to "rough skin".[3]

Paleobiology and parenting

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Artist's restoration of the oviraptoridNemegtomaiabrooding on its nest.

Many associations between adult oviraptorosaur skeletons or embryos with elongatoolithid eggs (includingMacroolithus) demonstrate thatMacroolithusand other elongatoolithids were laid by oviraptorosaurs.[1][14]One oviraptorosaur skeleton from theUpper CretaceousofChinawas described in 2005; two shelled elongatoolithid eggs were preserved inside of its pelvis. This suggests that oviraptorosaurs had two functionaloviductswhere both would produce eggs simultaneously. While Satoet al.did not refer the eggs specifically toMacroolithus,they noted that the eggs closely resembleM. yaotunensis,though with a thinner eggshell. The thin eggshell, however, could simply be because the shell had not finished forming when the mother died, or because of biochemical dissolution of the shell before fossilization.[15]

Multiple different genera of oviraptorids have been found on or near elongatoolithid nests indicating that oviraptorid parents wouldbroodon their eggs, most likely for extended periods of time.[16]There is some evidence to suggest that oviraptorid andtroodontideggs were cared for by the father, perhaps in apolygamoussystem.[17][10]Given the large size of eggs relative to the parent, a mother would only lay two eggs at a time, so the eggs of a single nest may have been contributed by multiple females.[15][17]

Nests

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A fossilized nest of oviraptorid eggs

Multiple well preservedMacroolithusnests are known, representingM. rugustusandM. yaotunensis.[3][5]A very well preserved clutch ofM. yaotunensiscontains 20 eggs arrayed in two, possibly three, circular layers. When complete this nest may have contained 40 or more eggs.[3]

Tanakaet al.(2015) found that among modern archosaurs (the group including birds, crocodilians, and dinosaurs), the porosity of eggshells can be used to accurately predict whether the eggs are buried or laid in open nests. They concluded thatMacroolithusnests were either open or only partially covered with vegetation.[18]The eggs' blue-green coloration could have acted as a camouflage to hide the nest from predators.[10]

M. rugustuseggs atTsagan Khushuin Mongolia represent a coastal colonial nesting site.[2]

Embryos

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A fewMacroolithuseggs preserve embryonic remains of oviraptorids inside.[19]Two eggs containing embryos found in theUpper CretaceousNanxiong FormationnearGanzhou, Jiangxiwere referred toM. yaotunensisin 2008. One of these embryos shows a much greater degree of bone development (ossification) than the other; it preserves ossified hind limbs and several vertebrae. The fact that the cervical vertebrae not only have ossifiedcentraandneural arches,but also have ossifiedzygapophyses,led Chenget al.to conclude that this embryo may in fact represent a hatchling, since in modernchickensandskuasthese zygaphyses are cartilaginous until hatching. Also, the embryo's foot anatomy (specifically, the proportions of itsmetatarsals) resembles that of the oviraptoridHeyuannia huangi,indicating that these eggs belong toH. huangior a similar species. The other egg has a much less developed embryo, with only the hind limbs preserved. While this does not permit comparison on the species level, the tibia (shinbone) confirms that it is an oviraptorosaur.[19]

Artist's restoration ofHeyuanniawith its nest

Three more eggs containing embryos from the same formation were described in 2016 by Wanget al.Though they noted that these eggs strongly resembleM. yaotunensis,they declined to refer them to any ootaxon lower than Elongatoolithidae becauseMacroolithusis not clearly defined and is in need of revision. The embryos within these eggs are some of the most well-preserved of any oviraptorids, providing new information on oviraptorid ontogeny. The specimens show a relatively shallow head which indicates that as oviraptorids matured, their skulls grew dorsoventrally (top-to-bottom) faster than anteroposteriorly (front-to-back). This growth pattern is unusual among theropods, but is also seen inderived( "advanced" )tyrannosaurids.Also unusual is that, even at this early stage of development, thenasal bonesare fused. Coincidentally, tyrannosaurids also show fusion of the nasals early in development.[14]

Pathology and extinction

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ManyMacroolithusspecimens in South China have double- or multiple-layering of cones on the inner surface of the eggshell, apathological conditionknown as ovum in ovo.[20]It is especially prevalent among eggs nearest to theCretaceous-Tertiary (K-T) boundary,which represents the end of theMesozoic Era.This pathology is correlated with a higher concentration oftrace elementslikeCo,Cr,Cu,Mn,Ni,Pb,Sr,V,andZn.[20]Experiments on modern birds have demonstrated that exposure to high levels of these elements will cause them to be incorporated into the eggshell, but the precise mechanism behind the pathological multi-layering is unknown. These abnormalities presumably affected hatchability of the eggs and may have played a role in the extinction of the dinosaurs.[14][20]However, the embryonic remains inside three multilayeredMacroolithus-like eggs from Ganzhou appear unaffected.[14]

The K-T boundary is associated withabnormally high amounts of iridium,an element which is rare in Earth's crust, but relatively common in asteroids and in Earth's core. This has been used as evidence that a meteorite impact caused the extinction of the dinosaurs (theAlvarez hypothesis). However, some paleontologists attribute the extinction event and the iridium anomaly to more gradual climatic change caused by the volcanic activity of theDeccan Traps.The Nanxiong Basin has special relevance to this discussion because it contains the K-T boundary. However, the position of boundary, as well as the duration of the extinction have been subject to debate. Zhaoet al.(2002 and 2009) have postulated that there were at least two iridium-delivering events over a time period consistent with the Deccan Traps volcanism, correlated with a gradual decline in diversity and eventual disappearance of fossil eggs from the Nanxiong Basin. According to their interpretation,Macroolithussurvived 250,000 years into the earlyPaleocene.[21][22][23]However, Bucket al.(2004) disputed these claims, arguing thatdebris flowsmixed and reworked thesedimentsnear the boundary, causing a blurring of the iridium anomaly and the appearance of eggshell fragments on both sides.[24]

Classification

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See also:Egg fossil § Classification

Fossilized eggs are classified in their own, parataxonomic system parallel toLinnaean taxonomy.Macroolithus,Elongatoolithus,andNanhsiungoolithuswere the first oogenera ever named in this system; they were classified in the oofamilyElongatoolithidae.[5]Cladistic analysis also supports the placement ofMacroolithusclose toElongatoolithus,together with other elongatoolithids in aclade.[25][26]Four oospecies are known:M. rugustus,M. yaotunensis,M. mutabilis,andM. lashuyuanensis.[1][27]The oogenus's microstructures are poorly-defined[1]and therefore may be in need of revision.[14]When Mikhailov describedM. mutabilis,he found no microstructural difference in Zhao's original illustrations ofM. rugustusandM. yaotunensis,but did notsynonymizethe oospecies because Chinese paleontologists considered them distinct.[2]

History

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See also:Timeline of egg fossil research

Discoveries

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Macroolithuseggs were first discovered in Southern China by the pioneering Chinese paleontologistYang Zhongjian.He described the remains of several fossil eggs from that region in 1965. Working prior to the advent of modern fossil egg parataxonomy, he gave them names as species ofOolithes,[3]a now-defunct name that was formerly used for various types of fossil eggs.[28][29]In 1975, Chinese paleontologist Zhao Zikui prototyped the modern parataxonomic system, creating a hierarchical system of oofamilies, oogenera, and oospecies. Zhao placed Yang'sO. rugustusinto the new oogenus,Macroolithus,splitting it into two oospecies,M. yaotunensisandM. rugustus.He also suggested that the American oospecies"Oolithes" carlylensis(which is now classified in a different elongatoolithid oogenus,Macroelongatoolithus[1]) be recombined asMacroolithus carlylensis.[5]

In 1991, the Russian paleontologist Konstantin Mikhailov introduced the modern classification of fossil eggs based on Zhao's parataxonomic naming system. He classified"O." carlylensisin the oofamilySpheroolithidae,but otherwise followed Zhao's 1975 classification ofMacroolithus.[30]In 1994 he namedM. mutabilis,a new oospecies ofMacroolithus,based on remains discovered in Mongolia.[2]

In 2000, a fourth oospecies,"M." turolensis,was described by Spanish paleontologists Olga Amo-Sanjuán, José Ignacio Canudo, and Gloria Cuenca-Bescós based on material from Spain. However, when new material of this oospecies was uncovered in 2014, it was moved into its own oogenus,Guegoolithus,which was furthermore moved to Spheroolithidae.[27]

In 2005, eggs possibly attributable toM. yaotunensiswere discovered paired inside the pelvis of a fossil oviraptorid skeleton.[15]In 2008, Chinese paleontologists Cheng Yen-nien, Ji Qiang, Wu Xiao-chun and Shan Hsi-yin discovered a pair of eggs representing the first in China to contain embryonic remains of oviraptorosaurs. Both eggs were referred toM. yaotunensis.[19]The fourth oospecies,M. lashuyuanensis,was described in 2009 by the Chinese paleontologists Fang Xiao-si, Li Pei-xian, Zhang Zhi-jun, Zhang Xian-qiu, Lin You-li, Guo Sheng-bin, Cheng Ye-ming, Li Zhen-yu, Zhang Xiao-jun and Cheng Zheng-wu.[9]

Paleobiological interpretations

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Restoration ofHeyuannia,the putative parent ofMacroolithus

In 1994, Mikhailov suggested thatMacroolithusrepresented the eggs of a large theropod, specificallyTarbosaurus,based on the large size of the eggs and the largely overlapping distribution.[2]However, the discovery of an oviraptorid embryo inside an elongatoolithid egg cast doubt on this hypothesis.[31]With the discovery of multiple oviraptorosaur-elongatoolithid associations in the late 1990s,[32]the eggs of elongatoolithids came to be accepted as belonging to oviraptorosaurian dinosaurs.[1]Oviraptorid parentage was confirmed forMacroolithuswhen, in 2008, oviraptorid embryos resemblingHeyuanniawere discovered inside a pair ofM. yaotunensiseggs in Jiangxi.[19]

Early on, paleontologists consideredMacroolithusnests to have been buried. Mou 1992 noted the high gas conductance values inMacroolithuseggs and therefore concluded that they were laid in a very humid environment, buried underground or inside a mound.[33]Deeming (2006) found a similar result. This seems to contradict evidence that oviraptorosaurids brooded bird-like on their eggs, but Deeming suggested thatOviraptorburied its eggs in a mound and thenOviraptorand its relatives sat atop a nest mound to incubate, rather than directly contacting the eggs.[34]However, Tanakaet al.(2015) criticized these results for lack of statistical rigor. They found, based on comparisons to modern eggs, thatMacroolithuswas predicted to be laid in open or partially covered nests.[18]Wiemannet al.(2017) also criticized Mou and Deeming because they had only measured eggshell porosity at the middle section of the eggs and did not take into account the fact that the pore density is much lower near the poles. This would lead to an overestimate of the total eggshell porosity and therefore an overstimate of the gas conductance value.[10]

The extinctions of Macroolithus and other eggs from Southern China have also had a history of different interpretations. In the 1990s, Chinese paleontologists, including the prominent egg specialist Zhao Zikui, observed a gradual reduction in dinosaur egg diversity during the final 200,000 to 300,000 years of the Cretaceous, with onlyMacroolithusranging up to the boundary.[20][35]They postulated, contrary to the impact hypothesis, that the extinction was the result of a prolonged drought that increased the concentration of trace heavy metals, which adversely affected eggshell and embryo development of the dinosaurs causing the population to gradually decline and collapse.[35]Zhaoet al.revised this hypothesis in 2002, postulating a gradual extinction ofMacroolithuscaused by the volcanism of the Deccan Traps.[21]In 2004, Bucket al.disputed this interpretation, arguing that the apparent gradual extinction was an illusion caused by reworking of sediments.[24]Zhaoet al.(2009) maintained that the extinction event was gradual.[22]

Distribution and paleoecology

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Macroolithusis known from myriad Late Cretaceous locations in China, Mongolia, and Kazakhstan.[1]

Henan

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InHenan,Macroolithus yaotunensiscoexists with the other elongatoolithidsElongatoolithus andrewsiandE. elongatus,as well asOvaloolithusandParaspheroolithusof theHugang,theLuyemiao,and theSigou Formations.These formations were formed during the Late Cretaceous in alacustrineorpalustrineenvironment. Dinosaur body fossils are rarely found in the same units, buttroodontids,tyrannosaurs, andhadrosaursare known from the same area.[8]

Shandong

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Some eggs tentatively assigned toMacroolithusare known from theWangshi GroupinLaiyang,Shandong.[36]The formations of theWangshi Groupwere deposited inalluvial fans,braided channelsand shallow lakes. Common fossils include hadrosaurids and dinosaur eggs.[37]

Southern China

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M. rugustus,M. yaotunensis,andM. lashuyuanensisare all known from theNanxiong BasininGuangdong.[5][9]This formation was deposited primary from streams, rivers, and lakes in that region.[21][35]It spans across theK/T boundary,at which point most of the dinosaur eggs disappear, butMacroolithusapparently exists on both sides of the boundary (which would imply that some species of dinosaurs survived into the early Tertiary).[21][22]However, sedimentological evidence suggests that these fossils were actually reworked by debris flows into the Tertiary rocks.[24]

The Nanxiong Basin is known for its abundance of fossil eggs, predominantly the oviraptorisaurian[1]eggsElongatoolithusandMacroolithus.[21]Other types of eggs include other elongatoolithids, as well asprismatoolithids,megaloolithids,andovaloolithids.[22]Footprints show that Nanxiong Basin was populated byornithopods,theropods,and possiblysauropods.[38]

Southern China, particularly theNanxiong FormationinJiangxi Province,possibly has the greatest oviraptorosaur diversity in the world,[39]and also includes several associations of oviraptorosaurs withMacroolithusor similar eggs.[19][15][14]Titanosaursandtyrannosauridsare also known from this area.[14]Non-dinosaur fauna includes lizards and the terrestrialnanhsiungchelyidturtles.[40]

Mongolia

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Macroolithus rugustusis abundant in theNemegt Formation,which dates to the lateCampanianto earlyMaastrichtian.[41][42]This formation represents depositions of a meandering river.[42]Well-preserved dinosaur remains are common in the Nemegt Formation,[43]including oviraptorosaurs,[42]titanosaurs,[44]troodontids, tyrannosaurs, ankylosaurs,[45]pachycephalosaurs,[46]hadrosaurs,[47]ornithomimosaurs,alvarezsaurs,[48]andtherizinosaurs.[49]Remains of small animals are relatively rare, but several types of birds are known from Nemegt,[48]as well as several types ofmultituberculatemammals.[50]Other fossil eggs from the Nemegt Formation includeOvaloolithus,Spheroolithus,Elongatoolithus,andLaevisoolithus.[41]

M. mutabilisis known solely at the Ikh-Shunkht locality from theBarun Goyot Formation,dating from theSantoniantoCampanian.[41][2]M. rugustusis also known from the Barun Goyot Formation, which represents a sand-dune filledeolianenvironment. Compared to the Nemegt Formation, large dinosaurs are rare at Barun Goyot, where the fauna is dominated by protoceratopsids, oviraptorids, and ankylosaurids.[51]Other types of fossil eggs from the Barun Goyot Formation includeProtoceratopsidovum,Gobioolithus,Faveoloolithus,Dendroolithus,Spheroolithus,andSubtiliolithus.[41]

Kazakhstan

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M. rugustushas also been found in theManrak Formation(also called Manrakskaya Svita) of theZaisan Basinin theEast Kazakhstan Region.This formation is near to theTayzhuzgen River,and dates to some time in the late Cretaceous, probably the Maastrictian.[2][4][31][52]

See also

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References

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  1. ^abcdefghijklmSimon, D. J. (2014). "Giant Dinosaur (theropod) Eggs of the Oogenus Macroelongatoolithus (Elongatoolithidae) from Southeastern Idaho: Taxonomic, Paleobiogeographic, and Reproductive Implications.Archived2016-03-04 at theWayback Machine"(Doctoral dissertation, Montana State University, Bozeman).
  2. ^abcdefghijklMikhailov, Konstantin K.E. (1994). "Theropod and protoceratopsian dinosaur eggs from the Cretaceous of Mongolia and Kazakhstan".Paleontological Journal.28(2): 101–120.
  3. ^abcdeYoung, Chung-chien (1965)."Fossil eggs from Nanhsiung, Kwangtun and Kanchou, Kiangsi"(PDF).Vertebrata PalAsiatica.9(2): 141–170.
  4. ^abMikhailov, Konstantin (2000). "Eggs and eggshells of dinosaurs and birds from the Cretaceous of Mongolia". In Benton, M.J.; Shishkin, M.A.; Unwin, D.M.; Kurochkin, E.N. (eds.).The Age of Dinosaurs in Russia and Mongolia.Cambridge University Press. pp. 560–572.
  5. ^abcdefghiZhao, Zikui (1975)."The microstructure of the dinosaurian eggshells of Nanxiong, Guangdong Province—on the classification of dinosaur eggs"(PDF).Vertebrata PalAsiatica.13(2): 105–117.
  6. ^Carpenter, K. (1999).Eggs, Nests, and Baby Dinosaurs: A Look at Dinosaur Reproduction.Indiana University Press. pp.294–295.ISBN9780253334978.
  7. ^Carpenter, Kenneth (1999). "How to Study a Fossil Egg".Eggs, Nests, and Baby Dinosaurs: A Look at Dinosaur Reproduction (Life of the Past).Bloomington, Indiana: Indiana University Press. pp.122–144.ISBN978-0-253-33497-8.
  8. ^abLiang, Xinquan; Wan, Shunü; Yang, Dongsheng; Zhou, Shiquan; Wu, Shichong (2009)."Dinosaur eggs and dinosaur egg-bearing deposits (Upper Cretaceous) of Henan Province, China: Occurrences, palaeoenvironments, taphonomy and preservation".Progress in Natural Science.19(11): 1587–1601.doi:10.1016/j.pnsc.2009.06.012.
  9. ^abcdFang, Xiaosi; Li, Peixian; Zhang, Zhijun; Lin, Youli; Guo, Shengbin; Cheng, Yeming; Li, Zhenyu; Zhang, Xiaojun; Cheng, Zhengwu (2009). "Quảng đông nam hùng bạch ác hệ cập khủng long đản đáo điểu đản diễn hóa nghiên cứu" [Cretaceous Strata in Nanxiong Basin of Guangdong and the Evolution from the Dinosaur Egg to the Bird Egg].Acta Geoscientia Sinica(in Chinese).30(2): 167–186.
  10. ^abcdWiemann, Jasmina; Yang, Tzu-Ruei; Sander, Philipp N.; Schneider, Marion; Engeser, Marianne; Kath-Schorr, Stephanie; Müller, Christa E.; Sander, Martin P. (2017)."Dinosaur origin of egg color: oviraptors laid blue-green eggs".PeerJ.5(e3706): e3706.doi:10.7717/peerj.3706.PMC5580385.PMID28875070.
  11. ^Banay, G.L. (1948)."An introduction to medical terminology i. Greek and Latin derivations".Bulletin of the Medical Library Association.36(1): 763–769.PMC194697.PMID16016791.
  12. ^Mikhailov, Konstantin E.; Bray, Emily S.; Hirsch, Karl F. (1996). "Parataxonomy of fossil eggs remains (Veterovata): Principles and applications".Journal of Vertebrate Paleontology.16(4): 763–769.doi:10.1080/02724634.1996.10011364.
  13. ^White, John Tahourdin (1858).Latin suffixes.London: Spottiswoode and Co. p.80.ensis latin root.
  14. ^abcdefgWang, Shuo; Zhang, Shukang; Sullivan, Corwin; Xu, Xing (2016)."Elongatoolithid eggs containing oviraptorid (Theropoda, Oviraptorosauria) embryos from the Upper Cretaceous of Southern China".BMC Evolutionary Biology.16(67): 67.doi:10.1186/s12862-016-0633-0.PMC4807547.PMID27012653.
  15. ^abcdSato, Tamaki; Cheng, Yen-nien; Wu, Xiao-chun; Zelenitsky, Darla; Hsiao, Yu-fu (2005)."A Pair of Shelled Eggs Inside A Female Dinosaur"(PDF).Science.308(5720): 375.doi:10.1126/science.1110578.PMID15831749.S2CID19470371.
  16. ^Fanti, F; Currie, PJ; Badamgarav, D (2012)."New Specimens ofNemegtomaiafrom the Baruungoyot and Nemegt Formations (Late Cretaceous) of Mongolia ".PLOS ONE.7(2): e31330.Bibcode:2012PLoSO...731330F.doi:10.1371/journal.pone.0031330.PMC3275628.PMID22347465.
  17. ^abVarricchio, David J.; Moore, Jason R.; Erickson, Gregory M.; Norell, Mark A.; Jackson, Frankie D.; Borkowski, John J. (2008). "Avian Paternal Care Had Dinosaur Origin".Science.322(5909): 1826–1827.Bibcode:2008Sci...322.1826V.doi:10.1126/science.1163245.PMID19095938.
  18. ^abTanaka, Kohei; Zelenitsky, Darla K.; Therrien, François (2015)."Eggshell Porosity Provides Insight on Evolution of Nesting in Dinosaurs".PLOS ONE.10(11): e0142829.Bibcode:2015PLoSO..1042829T.doi:10.1371/journal.pone.0142829.PMC4659668.PMID26605799.
  19. ^abcdeCheng, Yen-nien; Ji, Qiang; Wu, Xiao-chun; Shan, Hsi-y (2008). "Oviraptorosaurian Eggs (Dinosauria) with Embryonic Skeletons Discovered for the First Time in China".Acta Geologica Sinica.82(6): 1089–1094.doi:10.1111/j.1755-6724.2008.tb00708.x.S2CID140202077.
  20. ^abcdZhao, Zi-kui (1994). "Dinosaur eggs in China: On the structure and evolution of eggshells". In Carpenter, Kenneth; Hirsch, Karl F.; Horner, John R. (eds.).Dinosaur Eggs and Babies.Cambridge University Press. pp. 184–203.ISBN978-0-521-44342-5.
  21. ^abcdeZhao, Zikui; Mao, Xueming; Chai, Zhifang; Yang, Gaochuang; Kong, Ping; Ebihara, Mitsuru; Zhao, Zhenhua (2002). "A possible causal relationship between extinction of dinosaurs and K/T iridium enrichment in the Nanxiong Basin, South China: evidence from dinosaur eggshells".Palaeogeography, Palaeoclimatology, Palaeoecology.178(1–2): 1–17.Bibcode:2002PPP...178....1Z.doi:10.1016/S0031-0182(01)00361-3.
  22. ^abcdZhao, Zikui; Mao, Xueying; Chai, Zhifang; Yang, Gaochuang; Zhang, Fucheng; Yan, Zheng (2009). "Geochemical environmental changes and dinosaur extinction during the Cretaceous-Paleogene (K/T) transition in the Nanxiong Basin, South China: Evidence from dinosaur eggshells".Chinese Science Bulletin.54(5): 806.Bibcode:2009SciBu..54..806Z.doi:10.1007/s11434-008-0565-1.
  23. ^Wang, Qiang; Wang, Xiaolin; Zhao, Zikui (2010)."Recent Progress in the Study of Dinosaur Eggs in China"(PDF).Bulletin of the Chinese Academy of Sciences.24(2): 95–97. Archived fromthe original(PDF)on 2017-01-09.Retrieved2017-01-08.
  24. ^abcBuck, Brenda J.; Hanson, Andrew D.; Hengst, Richard A.; Hu, Shu-sheng (2004). ""Tertiary Dinosaurs" in the Nanxiong Basin, Southern China, Are Reworked from the Cretaceous ".Journal of Geology.112(1): 111–118.Bibcode:2004JG....112..111B.doi:10.1086/379695.S2CID12866840.
  25. ^Varricctio, David J.; Barta, Daniel E. (2015)."Revistiting Sabath's" Larger Avian Eggs "from the Gobi Cretaceous".Acta Palaeontologica Polonica.60(1): 11–25.doi:10.4202/app.00085.2014.
  26. ^Garcia, Geraldine; Marivaux, Laurent; Pélissié, Thierry; Vianey-Liaud, Monique (2006)."Earliest Laurisian sauropod eggshell"(PDF).Acta Palaeontologica Polonica.51(1): 99–104.
  27. ^abMoreno-Azanza, M.; Canudo, J.I.; Gasca, J.M. (2014)."Spheroolithid eggshells in the Lower Cretaceous of Europe. Implications for eggshell evolution in ornithischian dinosaurs"(PDF).Cretaceous Research.51:75–87.doi:10.1016/j.cretres.2014.05.017.
  28. ^Lawver, Daniel R.; Jackson, Frankie D. (2015)."A Review of the Fossil Record of Turtle Reproduction: Eggs, Embryos, Nests and Copulating Pairs"(PDF).Bulletin of the Peabody Museum of Natural History.55(2): 215–236.doi:10.3374/014.055.0210.S2CID86502368.
  29. ^Vianey-Liaud, Monique; Zelenitsky, Darla (2003). "Historical and new perspectives on the parataxonomy of fossil eggs".Paleovertebrata.32(2–4): 189–195.
  30. ^Mikhailov, Konstantin E. (1991)."Classification of Fossil Eggshells of Amniotic Vertebrates"(PDF).Acta Palaeontologica Polonica.36(2): 193–238.
  31. ^abMikhailov, K.E. (1997)."Fossil and Recent Eggshell in Amniotic Vertebrates: Fine Structure, Comparative Morphology and Classification".Special Papers in Palaeontology.56:64.
  32. ^Zelenitsky, Darla K.; Carpenter, Kenneth; Currie, Philip J. (2000). "First Record of Elongatoolithus Theropod Eggshell from North America: The Asian oogenusMacroelongatoolithusfrom the lower Cretaceous of Utah ".Journal of Vertebrate Paleontology.20(1): 130–138.doi:10.1671/0272-4634(2000)020[0130:FROETE]2.0.CO;2.S2CID86090590.
  33. ^Mou, Yun (1992)."Nest Environments of the Late Cretaceous Dinosaur eggs from Nanxiong Basin, Guangdong Province"(PDF).Vertebrata PalAsiatica.30(2): 120–134.
  34. ^Deeming, D.C. (2006)."Ultrastructural and Functional Morphology of Eggshells Supports the Idea that Dinosaur Eggs were Incubated Buried in a Substrate".Palaeontology.49(1): 171–185.doi:10.1111/j.1475-4983.2005.00536.x.
  35. ^abcZhao, Zikui; Ye, Jie; Li, Huamei; Zhao, Zhenhua; Yan, Zheng (1991)."Extinction of the dinosaurs across the Cretaceous-Tertiary Boundary in Nanxiong Basin, Guangdong Province"(PDF).Acta Paleontologica Sinica.29(1): 1–20.
  36. ^Zhao, Zikui (1979)."Progress in the Research of Dinosaur Eggs"(PDF).Mesozoic and Cenozoic Red Beds of South China.Selected Papers from the "Cretaceous-Tertiary Workshop," Nanxiong, Guangdong Province: 330–340.
  37. ^Wang, Qiang; Wang, Xiaolin; Zhao, Zikui; Zhang, Jialiang; Jiang, Shunxing (2013)."New turtle egg fossil from the Upper Cretaceous of the Laiyang Basin, Shandong Province, China".Anais da Academia Brasileira de Ciências.85(1): 103–111.doi:10.1590/S0001-37652013000100008.PMID23538955.
  38. ^Xing, Lida; Harris, Jerald D; Dong, Zhiming; Lin, Youli; Chen, Wei; Guo, Shengbin; Ji, Qiang (2009)."Ornithopod (Dinosauria: Ornithischia) tracks from the Upper Cretaceous Zhutian Formation in the Nanxiong basin, Guangdong, China and general observations on large Chinese ornithopd footprints"(PDF).Geological Bulletin of China.28(7): 829–843.
  39. ^Lü, Junchang; Pu, Hanyong; Kobayashi, Yoshitsugu; Xu, Li; Chang, Huali; Shang, Yuhua; Liu, Di; Lee, Yuong-Nam; Kundrát, Martin; Shen, Caizhi (2015)."A New Oviraptorid Dinosaur (Dinosauria: Oviraptorosauria) from the Late Cretaceous of Southern China and Its Paleobiogeographical Implications".Scientific Reports.5:11490.Bibcode:2015NatSR...511490L.doi:10.1038/srep11490.PMC4489096.PMID26133245.
  40. ^Tong, Haiyan; Mo, Jinyou (2010). "Jiangxichelys, a new nanhsiungchelyid turtle from the Late Cretaceous of Ganzhou, Jiangxi Province, China".Geological Magazine.147(6): 981–986.Bibcode:2010GeoM..147..981T.doi:10.1017/S0016756810000671.S2CID131484464.
  41. ^abcdMikhailov, Konstantin (1995)."Systematic, Faunistic and Stratigraphical Diversity of Cretaceous Eggs in Mongolia: Comparison with China".Sixth Symposium on Mesozoic Terrestrial Ecosystems and Biota, Short Papers:165–168.
  42. ^abcWeishampel, David B.; Fastovsky, David E.; Watabe, Mahito; Varricchio, David; Jackson, Frankie; Tsogtbaatar, Khishigjav; Barsbold, Rinchen (2008). "New Oviraptorid Embryoes from Bugin Tsav, Nemegt Formation (Upper Cretaceous), Mongolia, with Insights into Their Habitat and Crowth".Journal of Vertebrate Paleontology.28(4): 1110–1119.doi:10.1671/0272-4634-28.4.1110.S2CID84712926.
  43. ^Clarke, Julia A.; Norell, Mark A. (2004)."New Avialan Remains and a Review of the Known Avifauna from the Late Cretaceous Nemegt Formation of Mongolia".American Museum Novitates(3447): 1–12.doi:10.1206/0003-0082(2004)447<0001:NARAAR>2.0.CO;2.hdl:2246/2812.S2CID55687019.
  44. ^Wilson, Jeffrey A. (2005). "Redescription of the Mongolian SauropodNemegrosaurus mongoliensisNowinski (Dinosauria: Saurischia) and comments on Late Cretaceous Sauropod diversity ".Journal of Systematic Palaeontology.3(3): 283–318.doi:10.1017/S1477201905001628.S2CID54070651.
  45. ^Arbour, Victoria M.; Currie, Philip J.; Badamgarav, Demchig (2014). "The ankylosaurid dinosaurs of the Upper Cretaceous Baruungoyot and Nemegt formations of Mongolia".Zoological Journal of the Linnean Society.172(3): 631–652.doi:10.1111/zoj.12185.
  46. ^Evans, David C.; Brown, Caled Marshall; Ryan, Michael J.; Tsogtbaatar, Khishigjav (2011). "Cranial Ornamentation and Ontogenetic Status of Homalocephale calathocercos (Ornithischia: Pachycephalosauria) from the Nemegt Formation, Mongolia".Journal of Vertebrate Paleontology.31(1): 84–92.doi:10.1080/02724634.2011.546287.S2CID84908604.
  47. ^Maryanska, Teresa;Osmolska, Halszka (1982). "Firth Lambeosaurine Dinosaur from the Nemegt Formation, Upper Cretaceous, Mongolia".Acta Palaeontologica Polonica.26(3/4): 243–255.
  48. ^abClarke, Julia A.; Norrell, Mark A. (2004)."New Avialan Remains and a Review of the Known Avifauna from the Late Cretaceous Nemegt Formation of Mongolia"(PDF).American Museum Novitates(3447): 1–12.doi:10.1206/0003-0082(2004)447<0001:NARAAR>2.0.CO;2.hdl:2246/2812.S2CID55687019.
  49. ^Bell, Phil R.; Currie, Philip J.; Lee, Yuong-Nam (2012)."Tyrannosaur feeding traces onDeinocheirus(Theropod:?Ornithomimosauria) remains from the Nemegt Formation (Late Cretaceous), Mongolia ".Cretaceous Research.37:186–190.doi:10.1016/j.cretres.2012.03.018.
  50. ^Wible, John R.; Rougier, Guillermo W. (2000)."Cranial Anatomy ofKryptobaatar dashzevegi(Mammalia, Multituberculara) and its bearing on the evolution of mammalian characters "(PDF).Bulletin of the American Museum of Natural History.247:6.doi:10.1206/0003-0090(2000)247<0001:CAOKDM>2.0.CO;2.S2CID82849991.
  51. ^Longrich, Nicholas R.; Currie, Philip J.; Dong, Zhi-Ming (2010)."A new oviraptorid (Dinosauria: Theropoda) from the Upper Cretaceous of Bayan Mandahu, Inner Mongolia Authors".Palaeontology.53(5): 945–960.doi:10.1111/j.1475-4983.2010.00968.x.
  52. ^Averianov, Alexander O. (2007)."Theropod dinosaurs from Late Cretacoues depositys in the northeastern Aral Sea region, Kazakhstan"(PDF).Cretaceous Research.28(3): 532–544.doi:10.1016/j.cretres.2006.08.008.
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