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1. Comparison of δ ¹³ C analyses of individual foraminifer ( Orbulina universa ) shells by secondary ion mass spectrometry and gas source mass spectrometry

   https://doi.org/10.1002/rcm.9658  

   Wycech, Jody B; Kelly, Daniel Clay; Kozdon, Reinhard; Ishida, Akizumi; Kitajima, Kouki; Spero, Howard J; Valley, John W (January 2024, Rapid Communications in Mass Spectrometry)

   Abstract RationaleThe use of secondary ion mass spectrometry (SIMS) to perform micrometer‐scalein situcarbon isotope (δ¹³C) analyses of shells of marine microfossils called planktic foraminifers holds promise to explore calcification and ecological processes. The potential of this technique, however, cannot be realized without comparison to traditional whole‐shell δ¹³C values measured by gas source mass spectrometry (GSMS). MethodsPaired SIMS and GSMS δ¹³C values measured from final chamber fragments of the same shell of the planktic foraminiferOrbulina universaare compared. The SIMS–GSMS δ¹³C differences (Δ¹³C_SIMS‐GSMS) were determined via paired analysis of hydrogen peroxide‐cleaned fragments of modern cultured specimens and of fossil specimens from deep‐sea sediments that were either untreated, sonicated, and cleaned with hydrogen peroxide or vacuum roasted. After treatment, fragments were analyzed by a CAMECA IMS 1280 SIMS instrument and either a ThermoScientific MAT‐253 or a Fisons Optima isotope ratio mass spectrometer (GSMS). ResultsPaired analyses of cleaned fragments of cultured specimens (n = 7) yield no SIMS–GSMS δ¹³C difference. However, paired analyses of untreated (n = 18) and cleaned (n = 12) fragments of fossil shells yield average Δ¹³C_SIMS‐GSMSvalues of 0.8‰ and 0.6‰ (±0.2‰, 2 SE), respectively, while vacuum roasting of fossil shell fragments (n = 11) removes the SIMS–GSMS δ¹³C difference. ConclusionsThe noted Δ¹³C_SIMS‐GSMSvalues are most likely due to matrix effects causing sample–standard mismatch for SIMS analyses but may also be a combination of other factors such as SIMS measurement of chemically bound water. The volume of material analyzed via SIMS is ~10⁵times smaller than that analyzed by GSMS; hence, the extent to which these Δ¹³C_SIMS‐GSMSvalues represent differences in analyte or instrument factors remains unclear. 

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2. Ion microprobe–measured stable isotope evidence for ammonite habitat and life mode during early ontogeny

   https://doi.org/10.1017/pab.2018.21  

   Linzmeier, Benjamin J.; Landman, Neil H.; Peters, Shanan E.; Kozdon, Reinhard; Kitajima, Kouki; Valley, John W. (November 2018, Paleobiology)

   Abstract Ammonites have disparate adult morphologies indicative of diverse ecological niches, but ammonite hatchlings are small (~1 mm diameter), which raises questions about the similarity of egg incubation and hatchling life mode in ammonites. Modern Nautilus is sometimes used as a model organism for understanding ammonites, but despite their outward similarities, the groups are only distantly related. Trends in ammonite diversity and extinction vulnerability in the fossil record contrast starkly with those of nautilids, and embryonic shells from Late Cretaceous ammonites are two orders of magnitude smaller than nautilid embryonic shells. To investigate possible environmental changes experienced by ammonite hatchlings, we used secondary ion mass spectrometry to analyze the oxygen and carbon isotope composition of the embryonic shells and early postembryonic whorls of five juveniles of Hoploscaphites comprimus obtained from a single concretion in the Fox Hills Formation of South Dakota. Co-occurring bivalves and diagenetic calcite were also analyzed to provide a benthic baseline for comparison. The oxygen isotope ratios of embryonic shells are more like those of benthic bivalves, suggesting that ammonite eggs were laid on the bottom. Ammonite shell immediately after hatching has more negative δ 18 O, suggesting movement to more shallow water that is potentially warmer and/or fresher. After approximately one whorl of postembryonic growth, the values of δ 18 O become more positive in three of the five individuals, suggesting that these animals transitioned to a more demersal mode of life. Two other individuals transition to even lower δ 18 O values that could suggest movement to nearshore brackish water. These data suggest that ammonites, like many modern coleoids, may have spawned at different times of the year. Because scaphites were one of the short-term Cretaceous–Paleogene extinction survivors, it is possible that this characteristic allowed them to develop a broader geographic range and, consequently, a greater resistance to extinction. 

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3. Last Interglacial coastal hydroclimate variability in Bermuda revealed by clumped isotope oyster sclerochronology

   https://doi.org/10.1016/j.palaeo.2024.112195  

   Minnebo, Lillian; Winkelstern, Ian; Zhang, Jade; Petersen, Sierra (June 2024, Palaeogeography, Palaeoclimatology, Palaeoecology)

   Elliot, M (Ed.)

   The islands of Bermuda preserve carbonates from several glacial and interglacial intervals with demonstrated potential for reconstructing past North Atlantic climate. Here, we describe new clumped and conventional stable isotope data from Dendostrea (oyster) shells collected from a Last Interglacial / Marine Isotope Stage 5e (MIS 5e) deposit. Interpretation of these and past data is supported by new amino acid racemization age dating results from nine localities around Bermuda. We find that the fossil oyster population on Verrill Island (within the present Great Sound of Bermuda) records MIS 5e temperatures and water δ18O values that are similar to modern. These data contrast with the much cooler temperatures and lighter reconstructed water δ18O values reconstructed for sites on the southern shore. This contrast may in part be due to timing, with the Verrill Island deposit plausibly representing an earlier and warmer portion of MIS 5e. The data also reflect meaningful, highly local differences in environment, with modern Great Sound shells perhaps living in partially restricted waters buffered from cooler and groundwater-influenced conditions along the South Shore. The mobility of Cittarium pica marine snails used in previous work likely also introduces exaggerated variability in those cases. Critically, incorporation of clumped isotope data across multiple sites and genera enables an understanding of Bermudian MIS 5e climate that would be meaningfully different if given data from only one site. We seek to illustrate both the complexities and potential of working with clumped isotope paleoclimate data from coastal deposits. 

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4. A database of Holocene nearshore marine mollusc shell geochemistry from the Northeast Pacific

   https://doi.org/10.1594/PANGAEA.932671  

   Palmer, Hannah M; Padilla Vriesman, Veronica; Banker, Roxanne M; Bean, Jessica R (January 2021, PANGAEA - Data Publisher for Earth & Environmental Science)

   We compiled a database of previously published oxygen and carbon isotope data from archaeological, archival, and modern marine molluscs from the North American coast of the Northeast Pacific (32oN to 50oN). This database includes oxygen and carbon isotope data from over 550 modern, archaeological, and sub-fossil shells from 8880 years before present (BP) to the present, from which there are 4,845 total δ¹³C and 5,071 total δ¹⁸O measurements. Database includes the following parameters: paper of original publication, publication year, unique shell identification, unique subsample identification, sample number (given by original authors), subsample number (given by original author), number of subsamples per shell (added here), age in years before present, species, source (midden or modern), latitude, longitude, calculated sea surface temperature (only if published by original authors), tidal height, life mode, habitat, archaeological trinomial (when applicable), oxygen isotope value, and carbon isotope value. Shell dating and sampling strategies vary among studies (1-118 samples per shell) and vary significantly by journal discipline. Data are from various bivalves and gastropod species, with Mytilus spp. being the most commonly analyzed taxon. This novel database can be used to investigate changes in nearshore sea surface conditions including warm-cool oscillations, heat waves, and upwelling intensity, and provides nearshore calcite δ¹³C and δ¹⁸O values that can be compared to the vast collections of offshore foraminifera calcite δ¹³C and δ¹⁸O data from marine sediment cores. By utilizing previously published geochemical data from midden and museum shells rather than sampling new specimens, future scientific research can reduce or omit the alteration or destruction of culturally valued specimens and sites. 

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5. Compilation of a database of Holocene nearshore marine mollusk shell geochemistry from the California Current System

   https://doi.org/10.5194/essd-14-1695-2022  

   Palmer, Hannah M.; Padilla Vriesman, Veronica; Banker, Roxanne M.; Bean, Jessica R. (January 2022, Earth System Science Data)

   Abstract. The shells of marine invertebrates can serve as high-resolution records ofoceanographic and atmospheric change through time. In particular, oxygen andcarbon isotope analyses of nearshore marine calcifiers that grow byaccretion over their lifespans provide seasonal records of environmental andoceanographic conditions. Archaeological shell middens generated byIndigenous communities along the northwest coast of North America containshells harvested over multiple seasons for millennia. These shell middens,as well as analyses of archival and modern shells, have the potential toprovide multi-site, seasonal archives of nearshore conditions throughout theHolocene. A significant volume of oxygen and carbon isotope data fromarchaeological shells exist, yet they are separately published in archaeological,geochemical, and paleoceanographic journals and have not been comprehensivelyanalyzed to examine oceanographic change over time. Here, we compiled adatabase of previously published oxygen and carbon isotope data fromarchaeological, archival, and modern marine mollusks from the CaliforniaCurrent System (North American coast of the northeast Pacific, 32 to55∘ N). This database includes oxygen and carbon isotope data from 598modern, archaeological, and sub-fossil shells from 8880 years before present(BP) to the present, from which there are 4917 total δ13C and7366 total δ18O measurements. Shell dating and samplingstrategies vary among studies (1–345 samples per shell, mean 44.7 samplesper shell) and vary significantly by journal discipline. Data are fromvarious bivalves and gastropod species, with Mytilus spp. being the most commonlyanalyzed taxon. This novel database can be used to investigate changes innearshore sea surface conditions including warm–cool oscillations, heatwaves, and upwelling intensity, and it provides nearshore calcium carbonateδ13C and δ18O values that can be compared to thevast collections of offshore foraminiferal calcium carbonate δ13C and δ18O data from marine sediment cores. Byutilizing previously published geochemical data from midden and museumshells rather than sampling new specimens, future scientific research canreduce or omit the alteration or destruction of culturally valued specimensand sites. The dataset is publicly available through PANGAEA athttps://doi.org/10.1594/PANGAEA.941373 (Palmer et al.,2021). 

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