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Julia A Leethorp - One of the best experts on this subject based on the ideXlab platform.
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strontium isotope analysis of curved Tooth Enamel surfaces by laser ablation multi collector icp ms
Palaeogeography Palaeoclimatology Palaeoecology, 2014Co-Authors: P Le J Roux, Julia A Leethorp, Sandi R. Copeland, Matt Sponheimer, Darryl J De RuiterAbstract:Abstract Laser ablation multi-collector ICP-MS (LA-MC-ICP-MS) is increasingly applied to measure the strontium isotope composition ( 87 Sr/ 86 Sr) of fossil or modern Tooth samples in order to address questions about mobility. Recently, concerns have been raised that an analytical bias due to instrumental isotopic mass fractionation might be introduced when this method is used to sample across naturally curved Tooth Enamel surfaces. We address this concern by reanalyzing data that were originally produced using 750 μm linear LA-MC-ICP-MS scans on the external, slightly curved surfaces of fossil hominin teeth ( Australopithecus and Paranthropus ) from South Africa. By re-integrating the first and last 1/3 of the data along the original 750 μm linear scans, we compared 87 Sr/ 86 Sr results produced by sections of each scan with varying degrees of laser focus. The results show no evidence of any analytical scatter between strontium isotope values for the different sections of the curved Tooth surfaces and results for the different sections of each linear scan agree well within the precision of the method (external 2σ ± 0.0004). Furthermore, each analytical session was bracketed by analysis of a curved rodent ( Otomys sp.) Tooth in-house standard with up to ± 100 μm vertical change along the 750 μm linear scan. Long-term, average LA-MC-ICP-MS 87 Sr/ 86 Sr results for one such Otomys Tooth standard (0.72989 ± 0.00029, n = 71) agree well with the solution MC-ICP-MS analysis of the same Tooth (0.72976 ± 0.00002). New LA-MC-ICP-MS 87 Sr/ 86 Sr ratios, using both a 213 nm and solid-state 193 nm laser ablation system, for sets of consecutive 750 μm linear scans along the curved, outer Tooth Enamel surface on another single Otomys Tooth in-house standard agree within ± 0.0004 regardless of progressively more extreme vertical change during analysis (± 10 μm to ± 900 μm). These results are similar to LA-MC-ICP-MS Sr isotope analyses, using the same instrumentation and methodology, of an in-house, polished, flat clinopyroxene mineral standard (LA: 0.70482 ± 0.00029, n = 155; solution: 0.70495 ± 0.00003). We conclude that, provided the stable 86 Sr/ 88 Sr ratio is used in conjunction with the exponential law to constantly correct for instrumental isotopic mass fractionation during acquisition, curved Tooth Enamel surfaces represent no impediment to accurate LA-MC-ICP-MS strontium isotope analyses.
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stable isotopes in fossil hominin Tooth Enamel suggest a fundamental dietary shift in the pliocene
Philosophical Transactions of the Royal Society B, 2010Co-Authors: Julia A Leethorp, Darryl J De Ruiter, Matt Sponheimer, Benjamin H Passey, Thure E CerlingAbstract:Accumulating isotopic evidence from fossil hominin Tooth Enamel has provided unexpected insights into early hominin dietary ecology. Among the South African australopiths, these data demonstrate significant contributions to the diet of carbon originally fixed by C(4) photosynthesis, consisting of C(4) tropical/savannah grasses and certain sedges, and/or animals eating C(4) foods. Moreover, high-resolution analysis of Tooth Enamel reveals strong intra-Tooth variability in many cases, suggesting seasonal-scale dietary shifts. This pattern is quite unlike that seen in any great apes, even 'savannah' chimpanzees. The overall proportions of C(4) input persisted for well over a million years, even while environments shifted from relatively closed (ca 3 Ma) to open conditions after ca 1.8 Ma. Data from East Africa suggest a more extreme scenario, where results for Paranthropus boisei indicate a diet dominated (approx. 80%) by C(4) plants, in spite of indications from their powerful 'nutcracker' morphology for diets of hard objects. We argue that such evidence for engagement with C(4) food resources may mark a fundamental transition in the evolution of hominin lineages, and that the pattern had antecedents prior to the emergence of Australopithecus africanus. Since new isotopic evidence from Aramis suggests that it was not present in Ardipithecus ramidus at 4.4 Ma, we suggest that the origins lie in the period between 3 and 4 Myr ago.
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palaeoecology of late early miocene fauna in the namib based on 13c 12c and 18o 16o ratios of Tooth Enamel and ratite eggshell carbonate
Palaeogeography Palaeoclimatology Palaeoecology, 2009Co-Authors: Loic Segalen, Julia A LeethorpAbstract:Abstract We explored the stable light isotope ecology of a sample of extinct Namibian mammals from the early Miocene, a period when conditions are believed to have been relatively warm and moist. Where possible we compared isotope values of mammalian Tooth Enamel (Rhinocerotidae, Suidae, Climacoceratidae, Pliohyracidae, Gomphotheriidae and Deinotheriidae) with those of eggshells of a co-existing Aepyornithoid (19–20 Ma). In general, the isotopic values of Tooth Enamel in all mammalian fauna, including likely mixed feeders/grazers, are consistent with C 3 diets as expected for this period, and the ratite eggshells are consistently enriched in both 13 C and 18 O compared to the mammals. High eggshell carbon and oxygen isotope values at the sites of Grillental and Elisabethfeld suggest that ratite birds occupied a dry niche that possibly included CAM plants, while results for Langental suggest moister, cooler conditions. Arrisdrift (ca. 17–17.5 Ma) mammalian Tooth Enamel values overlap those of the 19–20 Ma sites. The dataset for Arrisdrift reveals distinctive patterning between species. In particular the two suid species differ significantly in δ 18 O and δ 13 C, suggesting distinct ecological niches consistent with predictions from their dental morphology. On the other hand, two distinct data populations for one species of Prohyrax may suggest different environmental conditions during the period in which the site formed.
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strontium isotope ratios 87sr 86sr of Tooth Enamel a comparison of solution and laser ablation multicollector inductively coupled plasma mass spectrometry methods
Rapid Communications in Mass Spectrometry, 2008Co-Authors: Sandi R. Copeland, Darryl J De Ruiter, Julia A Leethorp, Matt Sponheimer, Petrus Le Roux, Vaughan Grimes, Michael P RichardsAbstract:Strontium isotope ratios (87Sr/86Sr) in Tooth Enamel provide a means to investigate migration and landscape use in humans and other animals. Established methods for measuring 87Sr/86Sr in teeth use bulk sampling (5–20 mg) and labor-intensive elemental purification procedures before analysis by either thermal ionization mass spectrometry (TIMS) or multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS). Another method for measuring 87Sr/86Sr is laser ablation MC-ICP-MS, but concerns have been expressed about its accuracy for measuring Tooth Enamel. In this study we test the precision and accuracy of the technique by analyzing 30 modern rodent teeth from the Sterkfontein Valley, South Africa by laser ablation MC-ICP-MS and solution MC-ICP-MS. The results show a mean difference in 87Sr/86Sr measured by laser ablation and by solution of 0.0003 ± 0.0002. This degree of precision is well within the margin necessary for investigating the potential geographic origins of humans or animals in many areas of the world. Because laser ablation is faster, less expensive, and less destructive than bulk sampling solution methods, it opens the possibility for conducting 87Sr/86Sr analyses of intra-Tooth samples and small and/or rare specimens such as micromammal and fossil teeth. Copyright © 2008 John Wiley & Sons, Ltd.
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strontium isotope ratios 87sr 86sr of Tooth Enamel a comparison of solution and laser ablation multicollector inductively coupled plasma mass spectrometry methods
Rapid Communications in Mass Spectrometry, 2008Co-Authors: Sandi R. Copeland, Darryl J De Ruiter, Julia A Leethorp, Matt Sponheimer, Petrus Le Roux, Vaughan Grimes, Michael P RichardsAbstract:Strontium isotope ratios (87Sr/86Sr) in Tooth Enamel provide a means to investigate migration and landscape use in humans and other animals. Established methods for measuring (87)Sr/(86)Sr in teeth use bulk sampling (5-20 mg) and labor-intensive elemental purification procedures before analysis by either thermal ionization mass spectrometry (TIMS) or multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS). Another method for measuring 87Sr/86Sr is laser ablation MC-ICP-MS, but concerns have been expressed about its accuracy for measuring Tooth Enamel. In this study we test the precision and accuracy of the technique by analyzing 30 modern rodent teeth from the Sterkfontein Valley, South Africa by laser ablation MC-ICP-MS and solution MC-ICP-MS. The results show a mean difference in 87Sr/86Sr measured by laser ablation and by solution of 0.0003 +/- 0.0002. This degree of precision is well within the margin necessary for investigating the potential geographic origins of humans or animals in many areas of the world. Because laser ablation is faster, less expensive, and less destructive than bulk sampling solution methods, it opens the possibility for conducting 87Sr/86Sr analyses of intra-Tooth samples and small and/or rare specimens such as micromammal and fossil teeth.
Matt Sponheimer - One of the best experts on this subject based on the ideXlab platform.
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strontium isotope analysis of curved Tooth Enamel surfaces by laser ablation multi collector icp ms
Palaeogeography Palaeoclimatology Palaeoecology, 2014Co-Authors: P Le J Roux, Julia A Leethorp, Sandi R. Copeland, Matt Sponheimer, Darryl J De RuiterAbstract:Abstract Laser ablation multi-collector ICP-MS (LA-MC-ICP-MS) is increasingly applied to measure the strontium isotope composition ( 87 Sr/ 86 Sr) of fossil or modern Tooth samples in order to address questions about mobility. Recently, concerns have been raised that an analytical bias due to instrumental isotopic mass fractionation might be introduced when this method is used to sample across naturally curved Tooth Enamel surfaces. We address this concern by reanalyzing data that were originally produced using 750 μm linear LA-MC-ICP-MS scans on the external, slightly curved surfaces of fossil hominin teeth ( Australopithecus and Paranthropus ) from South Africa. By re-integrating the first and last 1/3 of the data along the original 750 μm linear scans, we compared 87 Sr/ 86 Sr results produced by sections of each scan with varying degrees of laser focus. The results show no evidence of any analytical scatter between strontium isotope values for the different sections of the curved Tooth surfaces and results for the different sections of each linear scan agree well within the precision of the method (external 2σ ± 0.0004). Furthermore, each analytical session was bracketed by analysis of a curved rodent ( Otomys sp.) Tooth in-house standard with up to ± 100 μm vertical change along the 750 μm linear scan. Long-term, average LA-MC-ICP-MS 87 Sr/ 86 Sr results for one such Otomys Tooth standard (0.72989 ± 0.00029, n = 71) agree well with the solution MC-ICP-MS analysis of the same Tooth (0.72976 ± 0.00002). New LA-MC-ICP-MS 87 Sr/ 86 Sr ratios, using both a 213 nm and solid-state 193 nm laser ablation system, for sets of consecutive 750 μm linear scans along the curved, outer Tooth Enamel surface on another single Otomys Tooth in-house standard agree within ± 0.0004 regardless of progressively more extreme vertical change during analysis (± 10 μm to ± 900 μm). These results are similar to LA-MC-ICP-MS Sr isotope analyses, using the same instrumentation and methodology, of an in-house, polished, flat clinopyroxene mineral standard (LA: 0.70482 ± 0.00029, n = 155; solution: 0.70495 ± 0.00003). We conclude that, provided the stable 86 Sr/ 88 Sr ratio is used in conjunction with the exponential law to constantly correct for instrumental isotopic mass fractionation during acquisition, curved Tooth Enamel surfaces represent no impediment to accurate LA-MC-ICP-MS strontium isotope analyses.
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stable isotopes in fossil hominin Tooth Enamel suggest a fundamental dietary shift in the pliocene
Philosophical Transactions of the Royal Society B, 2010Co-Authors: Julia A Leethorp, Darryl J De Ruiter, Matt Sponheimer, Benjamin H Passey, Thure E CerlingAbstract:Accumulating isotopic evidence from fossil hominin Tooth Enamel has provided unexpected insights into early hominin dietary ecology. Among the South African australopiths, these data demonstrate significant contributions to the diet of carbon originally fixed by C(4) photosynthesis, consisting of C(4) tropical/savannah grasses and certain sedges, and/or animals eating C(4) foods. Moreover, high-resolution analysis of Tooth Enamel reveals strong intra-Tooth variability in many cases, suggesting seasonal-scale dietary shifts. This pattern is quite unlike that seen in any great apes, even 'savannah' chimpanzees. The overall proportions of C(4) input persisted for well over a million years, even while environments shifted from relatively closed (ca 3 Ma) to open conditions after ca 1.8 Ma. Data from East Africa suggest a more extreme scenario, where results for Paranthropus boisei indicate a diet dominated (approx. 80%) by C(4) plants, in spite of indications from their powerful 'nutcracker' morphology for diets of hard objects. We argue that such evidence for engagement with C(4) food resources may mark a fundamental transition in the evolution of hominin lineages, and that the pattern had antecedents prior to the emergence of Australopithecus africanus. Since new isotopic evidence from Aramis suggests that it was not present in Ardipithecus ramidus at 4.4 Ma, we suggest that the origins lie in the period between 3 and 4 Myr ago.
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strontium isotope ratios 87sr 86sr of Tooth Enamel a comparison of solution and laser ablation multicollector inductively coupled plasma mass spectrometry methods
Rapid Communications in Mass Spectrometry, 2008Co-Authors: Sandi R. Copeland, Darryl J De Ruiter, Julia A Leethorp, Matt Sponheimer, Petrus Le Roux, Vaughan Grimes, Michael P RichardsAbstract:Strontium isotope ratios (87Sr/86Sr) in Tooth Enamel provide a means to investigate migration and landscape use in humans and other animals. Established methods for measuring 87Sr/86Sr in teeth use bulk sampling (5–20 mg) and labor-intensive elemental purification procedures before analysis by either thermal ionization mass spectrometry (TIMS) or multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS). Another method for measuring 87Sr/86Sr is laser ablation MC-ICP-MS, but concerns have been expressed about its accuracy for measuring Tooth Enamel. In this study we test the precision and accuracy of the technique by analyzing 30 modern rodent teeth from the Sterkfontein Valley, South Africa by laser ablation MC-ICP-MS and solution MC-ICP-MS. The results show a mean difference in 87Sr/86Sr measured by laser ablation and by solution of 0.0003 ± 0.0002. This degree of precision is well within the margin necessary for investigating the potential geographic origins of humans or animals in many areas of the world. Because laser ablation is faster, less expensive, and less destructive than bulk sampling solution methods, it opens the possibility for conducting 87Sr/86Sr analyses of intra-Tooth samples and small and/or rare specimens such as micromammal and fossil teeth. Copyright © 2008 John Wiley & Sons, Ltd.
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strontium isotope ratios 87sr 86sr of Tooth Enamel a comparison of solution and laser ablation multicollector inductively coupled plasma mass spectrometry methods
Rapid Communications in Mass Spectrometry, 2008Co-Authors: Sandi R. Copeland, Darryl J De Ruiter, Julia A Leethorp, Matt Sponheimer, Petrus Le Roux, Vaughan Grimes, Michael P RichardsAbstract:Strontium isotope ratios (87Sr/86Sr) in Tooth Enamel provide a means to investigate migration and landscape use in humans and other animals. Established methods for measuring (87)Sr/(86)Sr in teeth use bulk sampling (5-20 mg) and labor-intensive elemental purification procedures before analysis by either thermal ionization mass spectrometry (TIMS) or multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS). Another method for measuring 87Sr/86Sr is laser ablation MC-ICP-MS, but concerns have been expressed about its accuracy for measuring Tooth Enamel. In this study we test the precision and accuracy of the technique by analyzing 30 modern rodent teeth from the Sterkfontein Valley, South Africa by laser ablation MC-ICP-MS and solution MC-ICP-MS. The results show a mean difference in 87Sr/86Sr measured by laser ablation and by solution of 0.0003 +/- 0.0002. This degree of precision is well within the margin necessary for investigating the potential geographic origins of humans or animals in many areas of the world. Because laser ablation is faster, less expensive, and less destructive than bulk sampling solution methods, it opens the possibility for conducting 87Sr/86Sr analyses of intra-Tooth samples and small and/or rare specimens such as micromammal and fossil teeth.
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tracking changing environments using stable carbon isotopes in fossil Tooth Enamel an example from the south african hominin sites
Journal of Human Evolution, 2007Co-Authors: Julia A Leethorp, Matt Sponheimer, Julie LuytAbstract:Abstract The environmental contexts of the karstic hominin sites in South Africa have been established largely by means of faunal associations; taken together these data suggest a trend from relatively closed and more mesic to open, drier environments from about 3 to 1.5 Ma. Vrba argued for a major shift within this trend ca. 2.4–2.6 Ma, an influential proposal that posited links between bovid (and hominin) radiation in Africa and the intensification of Northern Hemisphere Glaciation. Yet faunal approaches often rely on habitat and feeding preferences of modern taxa that may differ from those of their extinct predecessors. Here we explore ways of extending 13C/12C data from fossil mammals beyond denoting “presence” or “absence” of C4 grasses using the evolution of open environments in South Africa as a case study. To do so we calculated the relative proportions of C3-, mixed-, and C4-feeding herbivores for all the hominin sites for which we have sufficient data based on 13C/12C analyses of fossil Tooth Enamel. The results confirm a general trend towards more open environments since 3 Ma, but they also emphasize a marked change to open grassy habitats in the latest Pliocene/early Pleistocene. Mean 13C/12C for large felids also mirrored this trend.
Darryl J De Ruiter - One of the best experts on this subject based on the ideXlab platform.
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strontium isotope analysis of curved Tooth Enamel surfaces by laser ablation multi collector icp ms
Palaeogeography Palaeoclimatology Palaeoecology, 2014Co-Authors: P Le J Roux, Julia A Leethorp, Sandi R. Copeland, Matt Sponheimer, Darryl J De RuiterAbstract:Abstract Laser ablation multi-collector ICP-MS (LA-MC-ICP-MS) is increasingly applied to measure the strontium isotope composition ( 87 Sr/ 86 Sr) of fossil or modern Tooth samples in order to address questions about mobility. Recently, concerns have been raised that an analytical bias due to instrumental isotopic mass fractionation might be introduced when this method is used to sample across naturally curved Tooth Enamel surfaces. We address this concern by reanalyzing data that were originally produced using 750 μm linear LA-MC-ICP-MS scans on the external, slightly curved surfaces of fossil hominin teeth ( Australopithecus and Paranthropus ) from South Africa. By re-integrating the first and last 1/3 of the data along the original 750 μm linear scans, we compared 87 Sr/ 86 Sr results produced by sections of each scan with varying degrees of laser focus. The results show no evidence of any analytical scatter between strontium isotope values for the different sections of the curved Tooth surfaces and results for the different sections of each linear scan agree well within the precision of the method (external 2σ ± 0.0004). Furthermore, each analytical session was bracketed by analysis of a curved rodent ( Otomys sp.) Tooth in-house standard with up to ± 100 μm vertical change along the 750 μm linear scan. Long-term, average LA-MC-ICP-MS 87 Sr/ 86 Sr results for one such Otomys Tooth standard (0.72989 ± 0.00029, n = 71) agree well with the solution MC-ICP-MS analysis of the same Tooth (0.72976 ± 0.00002). New LA-MC-ICP-MS 87 Sr/ 86 Sr ratios, using both a 213 nm and solid-state 193 nm laser ablation system, for sets of consecutive 750 μm linear scans along the curved, outer Tooth Enamel surface on another single Otomys Tooth in-house standard agree within ± 0.0004 regardless of progressively more extreme vertical change during analysis (± 10 μm to ± 900 μm). These results are similar to LA-MC-ICP-MS Sr isotope analyses, using the same instrumentation and methodology, of an in-house, polished, flat clinopyroxene mineral standard (LA: 0.70482 ± 0.00029, n = 155; solution: 0.70495 ± 0.00003). We conclude that, provided the stable 86 Sr/ 88 Sr ratio is used in conjunction with the exponential law to constantly correct for instrumental isotopic mass fractionation during acquisition, curved Tooth Enamel surfaces represent no impediment to accurate LA-MC-ICP-MS strontium isotope analyses.
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stable isotopes in fossil hominin Tooth Enamel suggest a fundamental dietary shift in the pliocene
Philosophical Transactions of the Royal Society B, 2010Co-Authors: Julia A Leethorp, Darryl J De Ruiter, Matt Sponheimer, Benjamin H Passey, Thure E CerlingAbstract:Accumulating isotopic evidence from fossil hominin Tooth Enamel has provided unexpected insights into early hominin dietary ecology. Among the South African australopiths, these data demonstrate significant contributions to the diet of carbon originally fixed by C(4) photosynthesis, consisting of C(4) tropical/savannah grasses and certain sedges, and/or animals eating C(4) foods. Moreover, high-resolution analysis of Tooth Enamel reveals strong intra-Tooth variability in many cases, suggesting seasonal-scale dietary shifts. This pattern is quite unlike that seen in any great apes, even 'savannah' chimpanzees. The overall proportions of C(4) input persisted for well over a million years, even while environments shifted from relatively closed (ca 3 Ma) to open conditions after ca 1.8 Ma. Data from East Africa suggest a more extreme scenario, where results for Paranthropus boisei indicate a diet dominated (approx. 80%) by C(4) plants, in spite of indications from their powerful 'nutcracker' morphology for diets of hard objects. We argue that such evidence for engagement with C(4) food resources may mark a fundamental transition in the evolution of hominin lineages, and that the pattern had antecedents prior to the emergence of Australopithecus africanus. Since new isotopic evidence from Aramis suggests that it was not present in Ardipithecus ramidus at 4.4 Ma, we suggest that the origins lie in the period between 3 and 4 Myr ago.
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strontium isotope ratios 87sr 86sr of Tooth Enamel a comparison of solution and laser ablation multicollector inductively coupled plasma mass spectrometry methods
Rapid Communications in Mass Spectrometry, 2008Co-Authors: Sandi R. Copeland, Darryl J De Ruiter, Julia A Leethorp, Matt Sponheimer, Petrus Le Roux, Vaughan Grimes, Michael P RichardsAbstract:Strontium isotope ratios (87Sr/86Sr) in Tooth Enamel provide a means to investigate migration and landscape use in humans and other animals. Established methods for measuring 87Sr/86Sr in teeth use bulk sampling (5–20 mg) and labor-intensive elemental purification procedures before analysis by either thermal ionization mass spectrometry (TIMS) or multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS). Another method for measuring 87Sr/86Sr is laser ablation MC-ICP-MS, but concerns have been expressed about its accuracy for measuring Tooth Enamel. In this study we test the precision and accuracy of the technique by analyzing 30 modern rodent teeth from the Sterkfontein Valley, South Africa by laser ablation MC-ICP-MS and solution MC-ICP-MS. The results show a mean difference in 87Sr/86Sr measured by laser ablation and by solution of 0.0003 ± 0.0002. This degree of precision is well within the margin necessary for investigating the potential geographic origins of humans or animals in many areas of the world. Because laser ablation is faster, less expensive, and less destructive than bulk sampling solution methods, it opens the possibility for conducting 87Sr/86Sr analyses of intra-Tooth samples and small and/or rare specimens such as micromammal and fossil teeth. Copyright © 2008 John Wiley & Sons, Ltd.
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strontium isotope ratios 87sr 86sr of Tooth Enamel a comparison of solution and laser ablation multicollector inductively coupled plasma mass spectrometry methods
Rapid Communications in Mass Spectrometry, 2008Co-Authors: Sandi R. Copeland, Darryl J De Ruiter, Julia A Leethorp, Matt Sponheimer, Petrus Le Roux, Vaughan Grimes, Michael P RichardsAbstract:Strontium isotope ratios (87Sr/86Sr) in Tooth Enamel provide a means to investigate migration and landscape use in humans and other animals. Established methods for measuring (87)Sr/(86)Sr in teeth use bulk sampling (5-20 mg) and labor-intensive elemental purification procedures before analysis by either thermal ionization mass spectrometry (TIMS) or multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS). Another method for measuring 87Sr/86Sr is laser ablation MC-ICP-MS, but concerns have been expressed about its accuracy for measuring Tooth Enamel. In this study we test the precision and accuracy of the technique by analyzing 30 modern rodent teeth from the Sterkfontein Valley, South Africa by laser ablation MC-ICP-MS and solution MC-ICP-MS. The results show a mean difference in 87Sr/86Sr measured by laser ablation and by solution of 0.0003 +/- 0.0002. This degree of precision is well within the margin necessary for investigating the potential geographic origins of humans or animals in many areas of the world. Because laser ablation is faster, less expensive, and less destructive than bulk sampling solution methods, it opens the possibility for conducting 87Sr/86Sr analyses of intra-Tooth samples and small and/or rare specimens such as micromammal and fossil teeth.
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sr ca and early hominin diets revisited new data from modern and fossil Tooth Enamel
Journal of Human Evolution, 2005Co-Authors: Darryl J De Ruiter, Julia A Leethorp, Matt Sponheimer, Andreas SpathAbstract:A previous study of strontium/calcium (Sr/Ca) ratios in Paranthropus suggested that it consumed more animal foods than was previously believed. However, that study looked at Sr/Ca in fossil bone, which is known to be highly susceptible to diagenesis. Enamel, in contrast, is resistant to post-mortem alteration making it a more appropriate material for Sr/Ca analysis of Plio-Pleistocene fossils. Yet, we know virtually nothing about Sr/Ca in the Enamel of modern African mammals, much less fossil taxa. To address this gap, we studied Sr/Ca in Tooth Enamel from modern mammals in the greater Kruger National Park, South Africa, as well as fossil fauna from the Sterkfontein Valley. Grazing herbivores have the highest Sr/Ca, followed by browsers and carnivores in both modern and fossil fauna. This similarity in ecological Sr/Ca patterning between modern and fossil fauna shows that diagenesis has not obscured the primary dietary signals. Australopithecus has significantly higher Sr/Ca than Paranthropus, and higher Sr/Ca than fossil papionins, browsers, and carnivores. Paranthropus has lower Sr/Ca than grazers, but its Sr/Ca is higher or equal to that of fossil papionins, browsers, and carnivores. Thus, Sr/Ca for both hominins is relatively high, and provides no direct evidence for omnivory in either taxon. The consumption of underground resources or insects are among the possible explanations for the highly elevated Sr/Ca in Australopithecus.
Michael P Richards - One of the best experts on this subject based on the ideXlab platform.
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strontium isotope ratios 87sr 86sr of Tooth Enamel a comparison of solution and laser ablation multicollector inductively coupled plasma mass spectrometry methods
Rapid Communications in Mass Spectrometry, 2008Co-Authors: Sandi R. Copeland, Darryl J De Ruiter, Julia A Leethorp, Matt Sponheimer, Petrus Le Roux, Vaughan Grimes, Michael P RichardsAbstract:Strontium isotope ratios (87Sr/86Sr) in Tooth Enamel provide a means to investigate migration and landscape use in humans and other animals. Established methods for measuring 87Sr/86Sr in teeth use bulk sampling (5–20 mg) and labor-intensive elemental purification procedures before analysis by either thermal ionization mass spectrometry (TIMS) or multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS). Another method for measuring 87Sr/86Sr is laser ablation MC-ICP-MS, but concerns have been expressed about its accuracy for measuring Tooth Enamel. In this study we test the precision and accuracy of the technique by analyzing 30 modern rodent teeth from the Sterkfontein Valley, South Africa by laser ablation MC-ICP-MS and solution MC-ICP-MS. The results show a mean difference in 87Sr/86Sr measured by laser ablation and by solution of 0.0003 ± 0.0002. This degree of precision is well within the margin necessary for investigating the potential geographic origins of humans or animals in many areas of the world. Because laser ablation is faster, less expensive, and less destructive than bulk sampling solution methods, it opens the possibility for conducting 87Sr/86Sr analyses of intra-Tooth samples and small and/or rare specimens such as micromammal and fossil teeth. Copyright © 2008 John Wiley & Sons, Ltd.
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strontium isotope ratios 87sr 86sr of Tooth Enamel a comparison of solution and laser ablation multicollector inductively coupled plasma mass spectrometry methods
Rapid Communications in Mass Spectrometry, 2008Co-Authors: Sandi R. Copeland, Darryl J De Ruiter, Julia A Leethorp, Matt Sponheimer, Petrus Le Roux, Vaughan Grimes, Michael P RichardsAbstract:Strontium isotope ratios (87Sr/86Sr) in Tooth Enamel provide a means to investigate migration and landscape use in humans and other animals. Established methods for measuring (87)Sr/(86)Sr in teeth use bulk sampling (5-20 mg) and labor-intensive elemental purification procedures before analysis by either thermal ionization mass spectrometry (TIMS) or multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS). Another method for measuring 87Sr/86Sr is laser ablation MC-ICP-MS, but concerns have been expressed about its accuracy for measuring Tooth Enamel. In this study we test the precision and accuracy of the technique by analyzing 30 modern rodent teeth from the Sterkfontein Valley, South Africa by laser ablation MC-ICP-MS and solution MC-ICP-MS. The results show a mean difference in 87Sr/86Sr measured by laser ablation and by solution of 0.0003 +/- 0.0002. This degree of precision is well within the margin necessary for investigating the potential geographic origins of humans or animals in many areas of the world. Because laser ablation is faster, less expensive, and less destructive than bulk sampling solution methods, it opens the possibility for conducting 87Sr/86Sr analyses of intra-Tooth samples and small and/or rare specimens such as micromammal and fossil teeth.
Sandi R. Copeland - One of the best experts on this subject based on the ideXlab platform.
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strontium isotope analysis of curved Tooth Enamel surfaces by laser ablation multi collector icp ms
Palaeogeography Palaeoclimatology Palaeoecology, 2014Co-Authors: P Le J Roux, Julia A Leethorp, Sandi R. Copeland, Matt Sponheimer, Darryl J De RuiterAbstract:Abstract Laser ablation multi-collector ICP-MS (LA-MC-ICP-MS) is increasingly applied to measure the strontium isotope composition ( 87 Sr/ 86 Sr) of fossil or modern Tooth samples in order to address questions about mobility. Recently, concerns have been raised that an analytical bias due to instrumental isotopic mass fractionation might be introduced when this method is used to sample across naturally curved Tooth Enamel surfaces. We address this concern by reanalyzing data that were originally produced using 750 μm linear LA-MC-ICP-MS scans on the external, slightly curved surfaces of fossil hominin teeth ( Australopithecus and Paranthropus ) from South Africa. By re-integrating the first and last 1/3 of the data along the original 750 μm linear scans, we compared 87 Sr/ 86 Sr results produced by sections of each scan with varying degrees of laser focus. The results show no evidence of any analytical scatter between strontium isotope values for the different sections of the curved Tooth surfaces and results for the different sections of each linear scan agree well within the precision of the method (external 2σ ± 0.0004). Furthermore, each analytical session was bracketed by analysis of a curved rodent ( Otomys sp.) Tooth in-house standard with up to ± 100 μm vertical change along the 750 μm linear scan. Long-term, average LA-MC-ICP-MS 87 Sr/ 86 Sr results for one such Otomys Tooth standard (0.72989 ± 0.00029, n = 71) agree well with the solution MC-ICP-MS analysis of the same Tooth (0.72976 ± 0.00002). New LA-MC-ICP-MS 87 Sr/ 86 Sr ratios, using both a 213 nm and solid-state 193 nm laser ablation system, for sets of consecutive 750 μm linear scans along the curved, outer Tooth Enamel surface on another single Otomys Tooth in-house standard agree within ± 0.0004 regardless of progressively more extreme vertical change during analysis (± 10 μm to ± 900 μm). These results are similar to LA-MC-ICP-MS Sr isotope analyses, using the same instrumentation and methodology, of an in-house, polished, flat clinopyroxene mineral standard (LA: 0.70482 ± 0.00029, n = 155; solution: 0.70495 ± 0.00003). We conclude that, provided the stable 86 Sr/ 88 Sr ratio is used in conjunction with the exponential law to constantly correct for instrumental isotopic mass fractionation during acquisition, curved Tooth Enamel surfaces represent no impediment to accurate LA-MC-ICP-MS strontium isotope analyses.
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strontium isotope ratios 87sr 86sr of Tooth Enamel a comparison of solution and laser ablation multicollector inductively coupled plasma mass spectrometry methods
Rapid Communications in Mass Spectrometry, 2008Co-Authors: Sandi R. Copeland, Darryl J De Ruiter, Julia A Leethorp, Matt Sponheimer, Petrus Le Roux, Vaughan Grimes, Michael P RichardsAbstract:Strontium isotope ratios (87Sr/86Sr) in Tooth Enamel provide a means to investigate migration and landscape use in humans and other animals. Established methods for measuring 87Sr/86Sr in teeth use bulk sampling (5–20 mg) and labor-intensive elemental purification procedures before analysis by either thermal ionization mass spectrometry (TIMS) or multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS). Another method for measuring 87Sr/86Sr is laser ablation MC-ICP-MS, but concerns have been expressed about its accuracy for measuring Tooth Enamel. In this study we test the precision and accuracy of the technique by analyzing 30 modern rodent teeth from the Sterkfontein Valley, South Africa by laser ablation MC-ICP-MS and solution MC-ICP-MS. The results show a mean difference in 87Sr/86Sr measured by laser ablation and by solution of 0.0003 ± 0.0002. This degree of precision is well within the margin necessary for investigating the potential geographic origins of humans or animals in many areas of the world. Because laser ablation is faster, less expensive, and less destructive than bulk sampling solution methods, it opens the possibility for conducting 87Sr/86Sr analyses of intra-Tooth samples and small and/or rare specimens such as micromammal and fossil teeth. Copyright © 2008 John Wiley & Sons, Ltd.
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strontium isotope ratios 87sr 86sr of Tooth Enamel a comparison of solution and laser ablation multicollector inductively coupled plasma mass spectrometry methods
Rapid Communications in Mass Spectrometry, 2008Co-Authors: Sandi R. Copeland, Darryl J De Ruiter, Julia A Leethorp, Matt Sponheimer, Petrus Le Roux, Vaughan Grimes, Michael P RichardsAbstract:Strontium isotope ratios (87Sr/86Sr) in Tooth Enamel provide a means to investigate migration and landscape use in humans and other animals. Established methods for measuring (87)Sr/(86)Sr in teeth use bulk sampling (5-20 mg) and labor-intensive elemental purification procedures before analysis by either thermal ionization mass spectrometry (TIMS) or multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS). Another method for measuring 87Sr/86Sr is laser ablation MC-ICP-MS, but concerns have been expressed about its accuracy for measuring Tooth Enamel. In this study we test the precision and accuracy of the technique by analyzing 30 modern rodent teeth from the Sterkfontein Valley, South Africa by laser ablation MC-ICP-MS and solution MC-ICP-MS. The results show a mean difference in 87Sr/86Sr measured by laser ablation and by solution of 0.0003 +/- 0.0002. This degree of precision is well within the margin necessary for investigating the potential geographic origins of humans or animals in many areas of the world. Because laser ablation is faster, less expensive, and less destructive than bulk sampling solution methods, it opens the possibility for conducting 87Sr/86Sr analyses of intra-Tooth samples and small and/or rare specimens such as micromammal and fossil teeth.
