131:" eggshells came from different taxa than the thicker eggshells, and subsequent researchers have come to support this idea. Another potential explanation for variation in eggshell thickness is that the thinner eggs were laid by younger individuals than older ones. There are also natural variations of eggshell thickness within a single species. Stressful environmental conditions may have resulted in dinosaur egg shells thinning. This may have played a role in dinosaur extinction, but is a controversial subject.
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194:. In the pathological specimens from Spain and Montana the redundant shell layer is as thick as in the original. In the specimen from Alberta it is only three fourths of the thickness of the original. The Utah specimen's pathological layer is only half that of the original. The egg is split open but still connected at one side. Some aspects of this egg suggests it was still in its mother's body when it was buried. The term
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eggshell pathologies, Karl F. Hirsch criticized these authors on the basis that multilayered eggs were "very unlikely" to allow embryos to hatch because even if the pores of the secondary shell layer were perfectly aligned with those of the primary layer the eggshell would still be too thick for the struggling neonate to break free.
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strata in Utah. Multilayered eggs can cause embryos to suffocate as the extraneous layer's pore canals won't line up well enough with the original layers' to allow gas to travel to the embryo. Multilayered dinosaur eggs are known from, in order of discovery, France, Spain, Mongolia, India, Argentina,
78:
facing opposite directions whereas egg shells that developed in layers on top of each other will have mammilae facing the same direction. Also, in stacked shells the layer separating the shells will resemble the sediment surrounding the fossil and in multilayer the layer between shells will resemble
89:
structures do not luminesce, signs of luminescence point to alterations to the chemical composition or structure of the shell. Magnesium-Calcite is sometimes replaced by
Manganese-Calcite, which luminesces bright red-orange or yellow orange. In multilayer eggs the shells will appear the same color,
198:
has been used for multilayered dinosaur eggs although this is inaccurate use of the term. Pathologies of eggshell are difficult to recognize in fossil specimens. Multilayered eggs are most common in the discretispherulitic egg morphotype and less common in others. This type of egg is attributed to
209:
eggs. Another multilayered egg from West
Germany is not a gecko egg. The shells of these eggs were broken in the typical fashion of hatching eggs, interpreted by the original describers as meaning that the pathological eggshell was not fatal to the developing embryos. In a 2001 survey of fossil
247:
has been used for multilayered dinosaur eggs although this is inaccurate use of the term. Pathologies of eggshell are difficult to recognize in fossil specimens. Hirsch concludes that the majority of pathological phenomena known to occur in modern eggs are not represented in the fossil record.
73:
in the fossil record. Multilayered eggshell identification can be complicated if the secondary eggshell is disconnected from the original. When this happens the two shells can vary in structure and may even be mistaken as coming from different types of eggs. Stacked eggshells from collapsed or
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and some experts have speculated that this was the cause of the species' extinction, with vegetation changes, climatic change and overcrowding being the original impetus for the shell thinning. However, there are alternative explanations for the thin eggshell not dependent on pathology. Later
233:. Eggs can be wrinkled, bulged, ridged, or have nodules. Eggs can be restricted, bound, or truncated. These pathological eggs often have shell units and internal microstructures that are not interlocked as tightly as those of healthy eggs. These phenomena have not been found in fossil eggs.
220:
specimens from
Colorado these are rare, but occupy almost the entire shell layer in specimens obtained from Late Cretaceous Montana. Egg shell has been recovered from the Milk River area of Alberta which may have been partially dissolved and then had additional calcite deposited on it.
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morphotypes. Multilayered fossil eggs resemble those of modern forms in sometimes having incomplete extra layers and pore canals that don't properly align. The shell membranes of these eggs have been either dissolved or been replaced with secondary
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sauropods. The greater abundance may indicate that these eggs were more prone to such pathologies, but are most likely due to a larger sample size of them. The pathological egg still inside its mother from Utah is a unique occurrence.
56:
to identify true paleopathologies in fossil eggs. Despite the diversity of paleopathologies known from fossil eggs, the vast majority of conditions known to afflict modern eggs have not yet been seen among fossils.
44:. Examples include eggshell of abnormal thickness and fossil eggs with multiple layers of eggshell. The identification of egg paleopathologies is complicated by the fact that even healthy eggs can be
469:
Hirsch, K. F., 2001, Pathological amniote eggshell – fossil and modern: In: Mesozoic
Vertebrate Life, edited by Tanke, D. H., and Carpenter, K., Indiana University Press, pp. 378–392.
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but the shell membrane between them tends to be replaced by manganese-calcite that luminseces bright orange. Manganese is the primary instigator of luminescence whereas iron hinders it.
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can be used to distinguish pathological egg shell from egg shell that has been altered diagenetically. Rigid egg shells, except in turtles, are composed of calcite. Since calcitic and
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researchers found resorption craters in the basal caps at the base of the columns, meaning that the eggs hatched. Some researchers postulated that the thinner "
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of the egg. Eggshell pathology can cause the shell to be so thin that the egg collapses. Abnormally thin eggshell has been attributed to
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compressed eggs may resemble multilayered eggshells but in thin cross-sections viewed under a microscope the stacked shell will have
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Irregularities in the surface of an egg and unusual egg shapes can be caused by convulsions or contractions of the
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of France and later India and
Argentina. More recent discoveries of this pathology have been in Late Cretaceous
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Eggs, Nests, and Baby
Dinosaurs: A Look at Dinosaur Reproduction (Life of the Past)
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323:"Pathologically and Diagenetically Altered Eggshell," Hirsch (2001); page 387.
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Abnormally thin eggshell can allow excessive evaporation to dehydrate the
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during or after fossilization. Paleontologists can use techniques like
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Canada, Montana, and Utah. Most multilayered dinosaur eggs are of the
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305:"Multilayered and Stacked Eggshell," Hirsch (2001); pages 386–387.
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is the study of evidence for illness, injury, and deformity in
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424:"Extraspherulitic Growth Units," Hirsch (2001); pages 385–386.
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growth units are sometimes found in otherwise normal eggs. In
314:"Multilayered and Stacked Eggshell," Hirsch (2001); page 387.
296:"Multilayered and Stacked Eggshell," Hirsch (2001); page 386.
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and has not yet been observed in the fossil record. The term
415:"Extraspherulitic Growth Units," Hirsch (2001); page 385.
173:. Other types of fossil eggs with these pathologies are
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strata from West
Germany have produced 27 multilayered
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conditions afflicting eggs have been documented in the
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the primary shell more than the surrounding sediment.
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69:make it difficult to confidently identify eggshell
433:"External Abnormalities," Hirsch (2001); page 379.
373:"Thick Eggshell," Hirsch (2001); pages 382–383.
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442:"Discussion," Hirsch (2001); pages 387–389.
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397:"Thick Eggshell," Hirsch (2001); page 384.
385:"Thick Eggshell," Hirsch (2001); page 383.
364:"Thick Eggshell," Hirsch (2001); page 382.
341:"Thin Eggshell," Hirsch (2001); page 381.
332:"Thin Eggshell," Hirsch (2001); page 380.
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406:"Discussion," Hirsch (2001); page 389.
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355:"Abstract," Hirsch (2001); page 378.
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146:and were first reported from the
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65:Differences in preservation and
114:have a negative impact on gas
1:
458:, Indiana University Press;
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454:Kenneth Carpenter, (1999)
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225:Undocumented pathologies
99:Abnormal shell thickness
241:preservation potential
94:Known paleopathologies
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128:Hypselosaurus priscus
121:Hypselosaurus priscus
22:Hypselosaurus priscus
19:
897:Egg drop competition
266:Paleontology portal
168:discretispherulitic
142:are known from the
107:or shell membrane.
83:Cathodoluminescence
50:cathodoluminescence
892:Egg-and-spoon race
719:List of egg dishes
532:Fish and amphibian
513:List of egg topics
187:prolatospherulitic
135:Multilayered shell
30:Egg paleopathology
27:
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952:Ovo vegetarianism
183:dendrospherulitic
140:Multilayered eggs
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54:thin sectioning
36:. A variety of
34:fossilized eggs
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38:pathological
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1032:Egg fossils
907:Fabergé egg
245:ovum in ovo
236:Ovum in ovo
196:ovum in ovo
71:pathologies
1026:Categories
917:HowToBasic
912:Free range
887:Easter egg
882:Decorating
864:In culture
754:Deep fried
675:Components
555:Cephalopod
449:References
274:Fossil egg
171:morphotype
109:Dehydrated
87:aragonitic
67:diagenesis
872:Balancing
834:Scrambled
646:Ovulation
636:Oviparity
616:Oogenesis
575:Pathology
537:Monotreme
285:Footnotes
203:Oligocene
175:prismatic
112:membranes
998:Category
799:Powdered
784:Omelette
779:Meringue
729:Benedict
696:membrane
596:Egg cell
569:dinosaur
252:See also
239:has low
218:Jurassic
164:oofamily
76:mammilae
46:modified
1010:Commons
979:Tossing
974:Tapping
969:Rolling
957:Pysanka
942:Organic
937:Oomancy
849:Soufflé
839:Shirred
804:Pickled
794:Poached
759:Deviled
744:Coddled
739:Century
711:As food
701:Chalaza
661:Trophic
631:Oviduct
621:Ootheca
591:Allergy
584:Biology
565:Reptile
192:calcite
166:with a
932:Oology
902:Egging
877:Carton
844:Smoked
829:Scotch
824:Salted
809:Quiche
764:Eggnog
734:Boiled
666:Zygote
611:Oogamy
601:Embryo
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231:uterus
185:, and
152:strata
105:embryo
819:Salad
769:Fried
724:Balut
692:Shell
687:White
656:Tooth
651:Spawn
626:Ovary
520:Types
207:gecko
927:Hunt
774:Iron
694:and
682:Yolk
560:Fish
527:Bird
504:Eggs
460:ISBN
25:egg.
854:Tea
814:Roe
52:or
1028::
390:^
378:^
346:^
181:,
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567:(
496:e
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