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Triple oxygen isotope ratios of bioapatite

dc.contributor.advisorPack, Andreas Prof. Dr.
dc.contributor.authorFeng, Dingsu
dc.titleTriple oxygen isotope ratios of bioapatitede
dc.contributor.refereeTütken, Thomas Prof.Dr.
dc.description.abstractengBioapatite is the major crystalline component of bone and tooth materials. Recent studies demonstrated that bioapatite carries information of animals’ physiology and living environmental conditions and retains its original isotope composition over millions of years. The triple oxygen isotope ratios of bioapatite for land-living mammals have proved to be a powerful tool to reconstruct paleo-atmospheric CO2 concentration. This thesis investigates variations in the triple oxygen isotope composition of bioapatite from a large collection of samples, including modern marine vertebrates, terrestrial mammals, birds and dinosaurs. In the following I will show and discuss: i) a new technique for high-precision triple oxygen isotope analysis of bioapatite; ii) a suite of triple oxygen isotope data of bioapatite from sharks and marine mammals; iii) a comprehensive triple oxygen isotope data set of terrestrial mammals with varying body sizes from different habitats; iv) triple oxygen isotope data for a collection of modern birds and dinosaurs from Late Cretaceous and Late Jurassic; vi) the methodology developed to obtain high precision triple oxygen isotope data. This thesis is organized in 5 chapters. Chapter 1 contains background, state of the art and main definitions and notations used throughout the thesis. In chapter 2, a new analytical protocol for high-precision triple oxygen isotope analyses is presented, together with triple oxygen isotope data of tooth enamel from 16 modern sharks and marine mammals. Results show that the analyzed sharks and mammals clearly separate from one another on a triple oxygen isotope plot. This is interpreted as the result of different proportions of metabolic oxygen in the bioapatite of marine vertebrates, i.e. more significant for marine mammals than for sharks. Data are then quantitatively discussed and interpreted in the framework of oxygen mass balance model for both sharks and marine mammals. Our data prove that triple oxygen isotope composition of bioapatite for, in particular, marine mammals is a suitable new proxy for the Δ'17O of atmospheric O2. In chapter 3, a comprehensive set of triple oxygen isotope data form 127 modern terrestrial mammals is presented and discussed. The data set covers a wide range of body masses from different environments and living conditions. Taxon specific oxygen mass balance models are presented and compared with the measured data. The results indicate that, due to their higher metabolic rates, small mammals are more sensitive to changes in air Δ'17O than large mammals. This makes tooth enamel from small mammals a well suited archive for Δ'17O of past atmospheric molecular O2. Chapter 4 contains triple oxygen isotope data of 11 modern birds and 9 dinosaurs. Modern birds’ data show similar variations in Δ'17O values to the terrestrial mammals. Hence, the mass balance model developed for terrestrial mammals is applied to estimate the oxygen isotopic balance of the studied dinosaurs. Fossil tooth enamel carries the O2 anomaly of ancient atmospheric air and holds the potential to be used as a proxy to reconstruct atmospheric paleo-CO2 levels. From the tooth enamel of four dinosaurs we estimate a Late Cretaceous atmospheric pCO2 of 817 ± 579 ppmv. A higher atmospheric CO2 level of 1605 ± 934 ppmv is obtained from the tooth enamel of five Late Jurassic specimens. These values are comparable to those reported in literature, obtained from different proxies. Chapter 5 shows the different methods experimented and all the extensive tests conducted for obtaining high precision triple oxygen isotope data of bioapatite. Pros and cons of the different approaches are discussed and the novel method is explained in detail. The final purpose of this thesis is threefold: to show that triple oxygen isotope data of tooth enamel from modern marine vertebrates and terrestrial mammals can be used to assess their physiology. To demonstrate that fossilized enamel of metabolically similar marine and terrestrial vertebrate is a new proxy for past atmospheric CO2 and global primary productivity. To reconstruct the Mesozoic atmospheric CO2 concentrations through high precision triple oxygen isotope analysis of tooth enamel from
dc.contributor.coRefereeHoefs, Jochen Prof. Dr.
dc.contributor.thirdRefereeWillbold, Matthias Prof. Dr.
dc.contributor.thirdRefereeThiel, Volker Prof. Dr.
dc.contributor.thirdRefereeGehler, Alexander Dr.
dc.subject.engCO2 concentrationde
dc.subject.engtriple oxygen isotopesde
dc.affiliation.instituteFakultät für Geowissenschaften und Geographiede
dc.subject.gokfullGeologische Wissenschaften (PPN62504584X)de

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