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Descripción
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| Oxygen and carbon isotope compositions of fossil bird eggshell calcite (?18Ocalc and ?13Ccalc) are regularly used to reconstruct paleoenvironmental conditions. However, the interpretation of ?18Ocalc values of fossil eggshells has been limited to qualitative variations in local climatic conditions as oxygen isotope fractionations between calcite, body fluids, and drinking water have not been determined yet. For this purpose, eggshell, albumen water, and drinking water of extant birds have been analyzed for their oxygen and carbon isotope compositions. Relative enrichments in 18O relative to 16O between body fluids and drinking water of +1.6 ± 0.9 ? for semi-aquatic birds and of +4.4 ± 1.9?for terrestrial birds are observed. Surprisingly, no significant dependence to body temperature on the oxygen isotope fractionation between eggshell calcite and body fluids is observed, suggesting that bird eggshells precipitate out of equilibrium. Two empirical equations relating the ?18Ocalc value of eggshell calcite to the ?18Ow value of ingested water have been established for terrestrial and semi-aquatic birds. These equations have been applied to fossil eggshells from Lanzarote in order to infer the ecologies of the Pleistocene marine bird Puffinus sp. and of the enigmatic giant birds from the Pliocene. Both ?13Ccalc and ?18Ocalc values of Puffinus eggshells point to a semiaquatic marine bird ingesting mostly seawater, whereas low ?13Ccalc and high ?18Ocalc values of eggshells from the Pliocene giant bird suggest a terrestrial lifestyle. This set of equations can help to quantitatively estimate the origin of waters ingested by extinct birds as well as to infer either local environmental or climatic conditions. | |
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Internacional
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JCR del ISI
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No |
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Título de la revista
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Science of Nature (2016) 103:81 |
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DOI
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10.1007/s00114-016-1404-x |
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2 |
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15 |
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