SIMS analyses of the oldest known assemblage of microfossils document their taxon-correlated carbon isotope compositions

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new collection</label> </li> <li> <input type="radio" id="collections-action-panel-existing" class="collections-existing" name="collections" value="existing" checked="true" data-ga-category="save_share" data-ga-action="collections" data-ga-label="collections_radio_existing"> <label for="collections-action-panel-existing">Add to an existing collection</label> </li> </ul> </div> <div class="controls-wrapper"> <div class="action-panel-control-wrap new-collections-controls"> <label for="collections-action-panel-add-to-new" class="action-panel-label required-field-asterisk"> Name your collection: </label> <input type="text" name="add-to-new-collection" id="collections-action-panel-add-to-new" class="collections-action-add-to-new" pattern="[^"&=<>\/]*" title="The following characters are not allowed in the Name field: "&=<>/" maxlength="100" data-ga-category="save_share" data-ga-action="create_collection" data-ga-label="non_favorties_collection"> <div class="collections-new-name-too-long usa-input-error-message selection-validation-message"> Name must be less than 100 characters </div> </div> <div class="action-panel-control-wrap existing-collections-controls"> <label for="collections-action-panel-add-to-existing" class="action-panel-label"> Choose a collection: </label> <select id="collections-action-panel-add-to-existing" class="action-panel-selector collections-action-add-to-existing" data-ga-category="save_share" data-ga-action="select_collection" data-ga-label="($('#collections-action-add-to-existing').val() === 'Favorites') ? 'Favorites' : 'non_favorites_collection'"> </select> <div class="collections-retry-load-on-error usa-input-error-message selection-validation-message"> Unable to load your collection due to an error<br> <a href="#">Please try again</a> </div> </div> </div> <div class="action-panel-actions"> <button class="action-panel-submit" type="submit" data-loading-label="Adding..." data-pinger-ignore data-ga-category="save_share" data-ga-action="collections" data-ga-label="add"> Add </button> <button class="action-panel-cancel" aria-label="Close 'Add to Collections' panel" ref="linksrc=close_collections_panel" aria-controls="collections-action-panel" aria-expanded="false" data-ga-category="save_share" data-ga-action="collections" data-ga-label="cancel"> Cancel </button> </div> </form> </div> </div> <div id="bibliography-action-panel" class="bibliography-action-panel action-panel in-progress-dots-panel" aria-hidden="true" data-bibliography-open-panel-enabled="false" data-bibliography-open-panel-url-hash="#open-bibliography-panel"> <div class="inner-wrap"> <h3 class="action-panel-heading"> Add to My Bibliography </h3> <form id="bibliography-action-panel-form" class="bibliography-action-panel-form action-panel-content action-form action-panel-smaller-selectors" data-add-to-bibliography-max-amount="100" data-add-to-bibliography-batch-size="10" data-bibliography-delegates-url="/list-bibliography-delegates/" data-add-to-bibliography-url="/add-to-bibliography/" data-get-article-ids-by-search-url="/get-article-ids-by-search/" data-mybib-root-url="https://www.ncbi.nlm.nih.gov/myncbi/collections/mybibliography/"> <input type="hidden" name="csrfmiddlewaretoken" value="I5DplRB9i5gwg7Ld6lAbZ12oHMJ3aOtuOyPA0yMDzLAhPwq70jb3UzVKJHxg4Akk"> <div class="action-panel-control-wrap bibliographies-controls"> <div class="choice-group"> <ul class="bibliographies-action-add radio-group-items"> <li> <input name="bibliography" id="my-bibliography" class="my-bibliography" type="radio" checked/> <label for="my-bibliography">My Bibliography</label> </li> </ul> </div> </div> <div class="bibliographies-retry-load-on-error usa-input-error-message selection-validation-message"> Unable to load your delegates due to an error<br> <a href="#">Please try again</a> </div> <div class="action-panel-actions"> <button class="action-panel-submit" type="submit" data-loading-label="Adding..." data-pinger-ignore> Add </button> <button class="action-panel-cancel" aria-label="Close 'Add to bibliography' panel" ref="linksrc=close_bibliography_panel" aria-controls="bibliography-action-panel" aria-expanded="false" data-ga-category="save_share" data-ga-action="mybib" data-ga-label="cancel"> Cancel </button> </div> </form> </div> </div> <div id="saved-search-action-panel" class="saved-search-action-panel action-panel " aria-hidden="true" data-saved-search-open-panel-enabled="false" data-saved-search-open-panel-url-hash="#open-saved-search-panel"> <div class="inner-wrap"> <h2 class="action-panel-heading"> Your saved search </h2> <form id="saved-search-action-panel-form" class="saved-search-action-panel-form action-panel-content action-form" data-create-saved-search-url="/create-saved-search/" data-try-search-terms-url="/try-search-term/" data-saved-search-root-url="https://www.ncbi.nlm.nih.gov/myncbi/searches/"> <input type="hidden" name="csrfmiddlewaretoken" value="I5DplRB9i5gwg7Ld6lAbZ12oHMJ3aOtuOyPA0yMDzLAhPwq70jb3UzVKJHxg4Akk"> <div class="action-panel-control-wrap"> <label for="saved-search-name" class="action-panel-label saved-search-name-label required-field-asterisk"> Name of saved search: </label> <input maxlength="200" type="text" name="saved-search-name" id="saved-search-name" class="saved-search-name" value="" required pattern="[^"&=<>\/]*" title="The following characters are not allowed in the Name field: "&=<>/"> </div> <div class="action-panel-control-wrap"> <label for="saved-search-term" class="action-panel-label required-field-asterisk"> Search terms: </label> <textarea name="saved-search-term" id="saved-search-term" class="saved-search-term" required></textarea> </div> <div class="test-search-term-wrap"> <a href="#" class="try-search-term">Test search terms</a> </div> <div class="choice-group action-panel-extra-margin-top"> <span class="action-panel-label" id="fieldset-label"> Would you like email updates of new search results? </span> <fieldset id="saved-search-alert" aria-describedby="fieldset-label"> <legend class="usa-sr-only">Saved Search Alert Radio Buttons</legend> <ul class="radio-group-items"> <li> <input type="radio" id="saved-search-alert-yes" class="saved-search-alert-yes" name="saved-search-alert" value="yes" checked> <label for="saved-search-alert-yes" class="action-panel-label">Yes</label> </li> <li> <input aria-label="No radio input" type="radio" id="saved-search-alert-no" class="saved-search-alert-no" name="saved-search-alert" value="no"> <label for="saved-search-alert-no" class="action-panel-label">No</label> </li> </ul> </fieldset> </div> <div class="alert-schedule-wrap"> <div class="action-panel-control-wrap"> <label class="action-panel-label"> Email: </label> <span aria-label="Email address" id="saved-search-email" class="action-panel-label"><span class="action-panel-label-bold"></span> (<a class="myncbi-account-settings" href="https://www.ncbi.nlm.nih.gov/account/settings/">change</a>)</span> </div> <div class="action-panel-control-wrap action-panel-extra-margin-top"> <label for="saved-search-frequency" class="action-panel-label"> Frequency: </label> <select id="saved-search-frequency" class="no-border-panel-selector saved-search-frequency"> <option value="monthly">Monthly</option> <option value="weekly">Weekly</option> <option value="daily">Daily</option> </select> </div> <div class="action-panel-control-wrap saved-search-monthly-additional"> <label for="saved-search-monthly-on-day" class="action-panel-label"> Which day? </label> <select id="saved-search-monthly-on-day" class="no-border-panel-selector"> <option value="Sunday">The first Sunday</option> <option value="Monday">The first Monday</option> <option value="Tuesday">The first Tuesday</option> <option value="Wednesday">The first Wednesday</option> <option value="Thursday">The first Thursday</option> <option value="Friday">The first Friday</option> <option value="Saturday">The first Saturday</option> <option value="day">The first day</option> <option value="weekday">The first weekday</option> </select> </div> <div class="action-panel-control-wrap saved-search-weekly-additional"> <label for="saved-search-weekly-on-day" class="action-panel-label"> Which day? </label> <select id="saved-search-weekly-on-day" class="no-border-panel-selector saved-search-weekly-on-day"> <option value="Sunday">Sunday</option> <option value="Monday">Monday</option> <option value="Tuesday">Tuesday</option> <option value="Wednesday">Wednesday</option> <option value="Thursday">Thursday</option> <option value="Friday">Friday</option> <option value="Saturday">Saturday</option> </select> </div> <div class="action-panel-control-wrap"> <label for="saved-search-report" class="action-panel-label"> Report format: </label> <select id="saved-search-report" class="no-border-panel-selector saved-search-report"> <option value="DocSum">Summary</option> <option value="DocSumText">Summary (text)</option> <option value="Abstract">Abstract</option> <option value="AbstractText">Abstract (text)</option> <option value="MEDLINE">PubMed</option> </select> </div> <div class="action-panel-control-wrap"> <label for="saved-search-amount" class="action-panel-label"> Send at most: </label> <select id="saved-search-amount" class="no-border-panel-selector saved-search-amount"> <option value="1">1 item</option> <option value="5" selected>5 items</option> <option value="10">10 items</option> <option value="20">20 items</option> <option value="50">50 items</option> <option value="100">100 items</option> <option value="200">200 items</option> </select> </div> <div> <input type="checkbox" id="saved-search-send-if-no-result" class="saved-search-send-if-no-result" name="saved-search-send-if-no-result"> <label for="saved-search-send-if-no-result" class="action-panel-label smaller-checkbox"> Send even when there aren't any new results </label> </div> <div class="action-panel-control-wrap option-text-in-email-wrap"> <label for="saved-search-email-text" class="action-panel-label"> Optional text in email: </label> <textarea name="saved-search-email-text" id="saved-search-email-text" class="saved-search-email-text"></textarea> </div> </div> <div class="action-panel-actions"> <button class="action-panel-submit" type="submit" data-loading-label="Saving..." data-ga-category="save_share" data-ga-action="alert" data-ga-label="save"> Save </button> <button class="action-panel-cancel" aria-label="Close 'Your saved search' panel" ref="linksrc=close_saved_search_panel" aria-controls="saved-search-action-panel" aria-expanded="false" data-ga-category="save_share" data-ga-action="alert" data-ga-label="cancel"> Cancel </button> </div> </form> </div> </div> <div id="citation-manager-action-panel" class="citation-manager-action-panel action-panel" aria-hidden="true"> <div class="inner-wrap"> <h2 class="action-panel-heading"> Create a file for external citation management software </h2> <form id="citation-manager-action-panel-form" class="action-panel-content action-form" action="/results-export-ids/" data-by-search-action="/results-export-search-data/" data-by-ids-action="/results-export-ids/" method="post" data-by-search-method="post" data-by-ids-method="post"> <input type="hidden" name="csrfmiddlewaretoken" value="I5DplRB9i5gwg7Ld6lAbZ12oHMJ3aOtuOyPA0yMDzLAhPwq70jb3UzVKJHxg4Akk"> <input name="results-format" type="hidden" value="pubmed"/> <div class="action-panel-actions"> <button class="action-panel-submit" type="submit" data-loading-label="Sending..." data-ga-category="save_share" data-ga-action="citation_manager" data-ga-label="save"> Create file </button> <button class="action-panel-cancel" aria-label="Close 'Send citations to citation manager' panel" ref="linksrc=close_citation_manager_panel" aria-controls="citation-manager-action-panel" aria-expanded="false" data-ga-category="save_share" data-ga-action="citation_manager" data-ga-label="cancel"> Cancel </button> </div> </form> </div> </div> <div id="rss-action-panel" class="rss-action-panel action-panel " aria-hidden="true"> <div class="inner-wrap"> <h2 class="action-panel-heading"> Your RSS Feed </h2> <form id="rss-action-panel-form" class="rss-action-panel-form action-panel-content action-form" data-create-rss-feed-url="/create-rss-feed-url/" data-search-form-term-value=""> <input type="hidden" name="csrfmiddlewaretoken" value="I5DplRB9i5gwg7Ld6lAbZ12oHMJ3aOtuOyPA0yMDzLAhPwq70jb3UzVKJHxg4Akk"> <div class="action-panel-control-wrap"> <label for="rss-name" class="action-panel-label required-field-asterisk"> Name of RSS Feed: </label> <input maxlength="200" placeholder="Name" type="text" name="rss-name" id="rss-name" class="rss-name" value='' required pattern="[^"&=<>\/]*" title="The following characters are not allowed in the Name field: "&=<>/"> </div> <div class="rss-limit-wrap"> <div class="action-panel-control-wrap action-panel-extra-margin-top"> <label for="rss-limit" class="action-panel-label"> Number of items displayed: </label> <select id="rss-limit" class="no-border-panel-selector rss-limit"> <option value="5">5</option> <option value="10">10</option> <option value="15" selected="selected">15</option> <option value="20">20</option> <option value="50">50</option> <option value="100">100</option> </select> </div> </div> <div class="action-panel-actions"> <button class="action-panel-submit" type="submit" data-loading-label="Creating..." data-ga-category="save_share" data-ga-action="alert" data-ga-label="save"> Create RSS </button> 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class="search-in-nlm-catalog-link dropdown-block-link" ref ="linksrc=search_in_nlm_catalog_link" href="https://www.ncbi.nlm.nih.gov/nlmcatalog?term=%22Proc+Natl+Acad+Sci+U+S+A%22%5BTitle+Abbreviation%5D" data-ga-category="search_catalog" data-ga-action="journal_link" data-ga-label="Proc Natl Acad Sci U S A"> Search in NLM Catalog </a></li><li><a class="add-to-search-link dropdown-block-link" ref ="linksrc=add_to_search_link" role="button" data-search-term='"Proc Natl Acad Sci U S A"[jour]' data-ga-category="search" data-ga-action="add_to_search" data-ga-label='"Proc Natl Acad Sci U S A"[jour]' href="#"> Add to Search </a></li></ul></div></div></div><span class="period">. </span><span class="cit">2018 Jan 2;115(1):53-58.</span> </div> <span class="citation-doi"> doi: 10.1073/pnas.1718063115. </span> <span class="secondary-date"> Epub 2017 Dec 18. </span> </div> <h1 class="heading-title"> SIMS analyses of the oldest known assemblage of microfossils document their taxon-correlated carbon isotope compositions </h1> <div class="inline-authors"> <div class="authors"> <div class="authors-list"> <span class="authors-list-item "><a class="full-name" href="/?term=Schopf+JW&cauthor_id=29255053" ref="linksrc=author_name_link" data-ga-category="search" data-ga-action="author_link" data-ga-label="J William Schopf">J William Schopf</a><sup class="affiliation-links"><span class="author-sup-separator"> </span><a class="affiliation-link" title="Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, CA 90095; schopf@epss.ucla.edu." href="#full-view-affiliation-1" ref="linksrc=author_aff"> 1 </a><span class="author-sup-separator"> </span><a class="affiliation-link" title="Center for the Study of Evolution and the Origin of Life, University of California, Los Angeles, CA 90095." href="#full-view-affiliation-2" ref="linksrc=author_aff"> 2 </a><span class="author-sup-separator"> </span><a class="affiliation-link" title="Molecular Biology Institute, University of California, Los Angeles, CA 90095." href="#full-view-affiliation-3" ref="linksrc=author_aff"> 3 </a><span class="author-sup-separator"> </span><a class="affiliation-link" title="Wisconsin Astrobiology Research Consortium, Department of Geoscience, University of Wisconsin, Madison, WI 53706." href="#full-view-affiliation-4" ref="linksrc=author_aff"> 4 </a></sup><span class="comma">, </span></span><span class="authors-list-item "><a class="full-name" href="/?term=Kitajima+K&cauthor_id=29255053" ref="linksrc=author_name_link" data-ga-category="search" data-ga-action="author_link" data-ga-label="Kouki Kitajima">Kouki Kitajima</a><sup class="affiliation-links"><span class="author-sup-separator"> </span><a class="affiliation-link" title="Wisconsin Astrobiology Research Consortium, Department of Geoscience, University of Wisconsin, Madison, WI 53706." href="#full-view-affiliation-4" ref="linksrc=author_aff"> 4 </a></sup><span class="comma">, </span></span><span class="authors-list-item "><a class="full-name" href="/?term=Spicuzza+MJ&cauthor_id=29255053" ref="linksrc=author_name_link" data-ga-category="search" data-ga-action="author_link" data-ga-label="Michael J Spicuzza">Michael J Spicuzza</a><sup class="affiliation-links"><span class="author-sup-separator"> </span><a class="affiliation-link" title="Wisconsin Astrobiology Research Consortium, Department of Geoscience, University of Wisconsin, Madison, WI 53706." href="#full-view-affiliation-4" ref="linksrc=author_aff"> 4 </a></sup><span class="comma">, </span></span><span class="authors-list-item "><a class="full-name" href="/?term=Kudryavtsev+AB&cauthor_id=29255053" ref="linksrc=author_name_link" data-ga-category="search" data-ga-action="author_link" data-ga-label="Anatoliy B Kudryavtsev">Anatoliy B Kudryavtsev</a><sup class="affiliation-links"><span class="author-sup-separator"> </span><a class="affiliation-link" title="Center for the Study of Evolution and the Origin of Life, University of California, Los Angeles, CA 90095." href="#full-view-affiliation-2" ref="linksrc=author_aff"> 2 </a></sup><span class="comma">, </span></span><span class="authors-list-item "><a class="full-name" href="/?term=Valley+JW&cauthor_id=29255053" ref="linksrc=author_name_link" data-ga-category="search" data-ga-action="author_link" data-ga-label="John W Valley">John W Valley</a><sup class="affiliation-links"><span class="author-sup-separator"> </span><a class="affiliation-link" title="Wisconsin Astrobiology Research Consortium, Department of Geoscience, University of Wisconsin, Madison, WI 53706." href="#full-view-affiliation-4" ref="linksrc=author_aff"> 4 </a></sup></span> </div> </div> </div> <div class="short-article-details"> Affiliations <button class="more-details" id="toggle-authors" data-alt-text="Collapse" aria-controls="expanded-authors" aria-expanded="false" data-pinger-ignore data-fetch-url="/29255053/long-authors/" data-id-prefix=""> <span class="title"> Expand </span> 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Astrobiology Research Consortium, Department of Geoscience, University of Wisconsin, Madison, WI 53706.</li> </ul> </div> </div> </div> <ul class="identifiers" id="full-view-identifiers"> <li> <span class="identifier pubmed"> <span class="id-label"> PMID: </span> <strong class="current-id" title="PubMed ID">29255053</strong> </span> </li> <li> <span class="identifier pmc"> <span class="id-label"> PMCID: </span> <a class="id-link" target="_blank" rel="noopener" ref="linksrc=article_id_link&article_id=PMC5776830&id_type=PMC" href="https://pmc.ncbi.nlm.nih.gov/articles/PMC5776830/" data-ga-category="full_text" data-ga-action="PMCID" > PMC5776830 </a> </span> </li> <li> <span class="identifier doi"> <span class="id-label"> DOI: </span> <a class="id-link" target="_blank" rel="noopener" ref="linksrc=article_id_link&article_id=10.1073/pnas.1718063115&id_type=DOI" href="https://doi.org/10.1073/pnas.1718063115" data-ga-category="full_text" data-ga-action="DOI" > 10.1073/pnas.1718063115 </a> </span> </li> </ul> <div class="in-clipboard-label " hidden> Item in Clipboard </div> </div> <div class="short-view" id="short-view-heading"> <h1 class="heading-title"> SIMS analyses of the oldest known assemblage of microfossils document their taxon-correlated carbon isotope compositions </h1> <div class="short-citation"> <span class="authors-list"> <span class="authors-list-item "><span class="full-name">J William Schopf</span><span class="citation-separator"> et al.</span></span> </span> <span class="citation-journal"> Proc Natl Acad Sci U S A<span class="citation-separator">.</span> </span> <span class="date"> <time class="citation-year" datetime="2018">2018</time><span class="citation-separator">.</span> </span> </div> <div class="more-article-details-section with-display-settings"> <button class="more-article-details" id="toggle-article-details" data-alt-text="Hide details" ref="linksrc=toggle_article_details" aria-controls="full-article-details" aria-expanded="false" 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class="cit">2018 Jan 2;115(1):53-58.</span> </div> <span class="citation-doi"> doi: 10.1073/pnas.1718063115. </span> <span class="secondary-date"> Epub 2017 Dec 18. </span> </div> <div class="expanded-authors" id="short-view-expanded-authors"> <div class="authors"> <h3 class="title"> Authors </h3> <div class="authors-list"> <span class="authors-list-item "><a class="full-name" href="/?term=Schopf+JW&cauthor_id=29255053" ref="linksrc=author_name_link" data-ga-category="search" data-ga-action="author_link" data-ga-label="J William Schopf">J William Schopf</a><sup class="affiliation-links"><span class="author-sup-separator"> </span><a class="affiliation-link" title="Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, CA 90095; schopf@epss.ucla.edu." href="#short-view-affiliation-1" ref="linksrc=author_aff"> 1 </a><span class="author-sup-separator"> </span><a class="affiliation-link" title="Center for the Study of Evolution and the Origin of Life, University of California, Los Angeles, CA 90095." href="#short-view-affiliation-2" ref="linksrc=author_aff"> 2 </a><span class="author-sup-separator"> </span><a class="affiliation-link" title="Molecular Biology Institute, University of California, Los Angeles, CA 90095." href="#short-view-affiliation-3" ref="linksrc=author_aff"> 3 </a><span class="author-sup-separator"> </span><a class="affiliation-link" title="Wisconsin Astrobiology Research Consortium, Department of Geoscience, University of Wisconsin, Madison, WI 53706." href="#short-view-affiliation-4" ref="linksrc=author_aff"> 4 </a></sup><span class="comma">, </span></span><span class="authors-list-item "><a class="full-name" href="/?term=Kitajima+K&cauthor_id=29255053" ref="linksrc=author_name_link" data-ga-category="search" data-ga-action="author_link" data-ga-label="Kouki Kitajima">Kouki Kitajima</a><sup class="affiliation-links"><span class="author-sup-separator"> </span><a class="affiliation-link" title="Wisconsin Astrobiology Research Consortium, Department of Geoscience, University of Wisconsin, Madison, WI 53706." href="#short-view-affiliation-4" ref="linksrc=author_aff"> 4 </a></sup><span class="comma">, </span></span><span class="authors-list-item "><a class="full-name" href="/?term=Spicuzza+MJ&cauthor_id=29255053" ref="linksrc=author_name_link" data-ga-category="search" data-ga-action="author_link" data-ga-label="Michael J Spicuzza">Michael J Spicuzza</a><sup class="affiliation-links"><span class="author-sup-separator"> </span><a class="affiliation-link" title="Wisconsin Astrobiology Research Consortium, Department of Geoscience, University of Wisconsin, Madison, WI 53706." href="#short-view-affiliation-4" ref="linksrc=author_aff"> 4 </a></sup><span class="comma">, </span></span><span class="authors-list-item "><a class="full-name" href="/?term=Kudryavtsev+AB&cauthor_id=29255053" ref="linksrc=author_name_link" data-ga-category="search" data-ga-action="author_link" data-ga-label="Anatoliy B Kudryavtsev">Anatoliy B Kudryavtsev</a><sup class="affiliation-links"><span class="author-sup-separator"> </span><a class="affiliation-link" title="Center for the Study of Evolution and the Origin of Life, University of California, Los Angeles, CA 90095." href="#short-view-affiliation-2" ref="linksrc=author_aff"> 2 </a></sup><span class="comma">, </span></span><span class="authors-list-item "><a class="full-name" href="/?term=Valley+JW&cauthor_id=29255053" ref="linksrc=author_name_link" data-ga-category="search" data-ga-action="author_link" data-ga-label="John W Valley">John W Valley</a><sup class="affiliation-links"><span class="author-sup-separator"> </span><a class="affiliation-link" title="Wisconsin Astrobiology Research Consortium, Department of Geoscience, University of Wisconsin, Madison, WI 53706." href="#short-view-affiliation-4" ref="linksrc=author_aff"> 4 </a></sup></span> </div> </div> <div class="affiliations"> <h3 class="title"> Affiliations </h3> <ul class="item-list"> <li data-affiliation-id="short-view-affiliation-1" id="short-view-affiliation-1" ><sup class="key">1</sup> Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, CA 90095; schopf@epss.ucla.edu.</li> <li data-affiliation-id="short-view-affiliation-2" id="short-view-affiliation-2" ><sup class="key">2</sup> Center for the Study of Evolution and the Origin of Life, University of California, Los Angeles, CA 90095.</li> <li data-affiliation-id="short-view-affiliation-3" id="short-view-affiliation-3" ><sup class="key">3</sup> Molecular Biology Institute, University of California, Los Angeles, CA 90095.</li> <li data-affiliation-id="short-view-affiliation-4" id="short-view-affiliation-4" ><sup class="key">4</sup> Wisconsin Astrobiology Research Consortium, Department of Geoscience, University of Wisconsin, Madison, WI 53706.</li> </ul> </div> </div> <ul class="identifiers" id="short-view-identifiers"> <li> <span class="identifier pubmed"> <span class="id-label"> PMID: </span> <strong class="current-id" title="PubMed ID">29255053</strong> </span> </li> <li> <span class="identifier pmc"> <span class="id-label"> PMCID: </span> <a class="id-link" target="_blank" rel="noopener" ref="linksrc=article_id_link&article_id=PMC5776830&id_type=PMC" href="https://pmc.ncbi.nlm.nih.gov/articles/PMC5776830/" data-ga-category="full_text" data-ga-action="PMCID" > PMC5776830 </a> </span> </li> <li> <span class="identifier doi"> <span class="id-label"> DOI: </span> <a class="id-link" target="_blank" rel="noopener" ref="linksrc=article_id_link&article_id=10.1073/pnas.1718063115&id_type=DOI" href="https://doi.org/10.1073/pnas.1718063115" data-ga-category="full_text" data-ga-action="DOI" > 10.1073/pnas.1718063115 </a> </span> </li> </ul> <div class="in-clipboard-label " hidden> Item in Clipboard </div> </div> </div> </header> <div class="actions-buttons inline"><div class="inner-wrap"><button class="full-text-links-button full-text-links-dialog-trigger" title="Open dialog with full text links" ref="linksrc=full_text_links"> Full text links </button><button class="citation-button citation-dialog-trigger" aria-label="Open dialog with citation text in different styles" data-ga-category="save_share" data-ga-action="cite" data-ga-label="open" data-all-citations-url="/29255053/citations/" data-citation-style="nlm" data-pubmed-format-link="/29255053/export/"><span class="button-label">Cite</span></button><button class="more-actions-button more-actions-dialog-trigger" title="Open dialog with more actions to take" ref="linksrc=more_actions_btn"></button><div class="display-options" data-format-key="format" data-default-format-value="abstract" data-current-format-value="abstract" role="region"><button class="trigger usa-button" title="Change format" data-ga-category="display_options" data-ga-action="display_options_dialog"><span class="button-label">Display options</span></button><div class="dropdown" hidden><div class="title"> Display options </div><div class="content"><div class="format-container"><span class="option-label"> Format </span><select name="format" data-initial-value="abstract" aria-label="Display format" id="inline-actions-display-format"><option value="abstract">Abstract</option><option value="pubmed">PubMed</option><option value="pmid">PMID</option></select></div></div></div></div></div></div> <div class="abstract" id="abstract"> <h2 class="title"> Abstract </h2> <div class="abstract-content selected" id="eng-abstract"> <p> Analyses by secondary ion mass spectroscopy (SIMS) of 11 specimens of five taxa of prokaryotic filamentous kerogenous cellular microfossils permineralized in a petrographic thin section of the ∼3,465 Ma Apex chert of northwestern Western Australia, prepared from the same rock sample from which this earliest known assemblage of cellular fossils was described more than two decades ago, show their δ<sup>13</sup>C compositions to vary systematically taxon to taxon from -31‰ to -39‰. These morphospecies-correlated carbon isotope compositions confirm the biogenicity of the Apex fossils and validate their morphology-based taxonomic assignments. Perhaps most significantly, the δ<sup>13</sup>C values of each of the five taxa are lower than those of bulk samples of Apex kerogen (-27‰), those of SIMS-measured fossil-associated dispersed particulate kerogen (-27.6‰), and those typical of modern prokaryotic phototrophs (-25 ± 10‰). The SIMS data for the two highest δ<sup>13</sup>C Apex taxa are consistent with those of extant phototrophic bacteria; those for a somewhat lower δ<sup>13</sup>C taxon, with nonbacterial methane-producing Archaea; and those for the two lowest δ<sup>13</sup>C taxa, with methane-metabolizing γ-proteobacteria. Although the existence of both methanogens and methanotrophs has been inferred from bulk analyses of the carbon isotopic compositions of pre-2,500 Ma kerogens, these in situ SIMS analyses of individual microfossils present data interpretable as evidencing the cellular preservation of such microorganisms and are consistent with the near-basal position of the Archaea in rRNA phylogenies. </p> </div> <p> <strong class="sub-title"> Keywords: </strong> Apex chert; Archaea; Archean; methanogens; methanotrophs. </p> </div> <p class="disclaimer" id="disclaimer"> <a href="/disclaimer/" target="_blank" data-ga-category="literature_resources" data-ga-action="disclaimer_link" data-ga-label="under_abstract">PubMed Disclaimer</a> </p> <div class="conflict-of-interest" id="conflict-of-interest"> <h2 class="title"> Conflict of interest statement </h2> <div class="statement"> <p xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:p1="http://pubmed.gov/pub-one">The authors declare no conflict of interest.</p> </div> </div> <div class="figures" id="figures"> <h2 class="title"> Figures </h2> <div class="figures-list" id="slides-container" itemscope itemtype="http://schema.org/ImageGallery"> <figure class="figure-item " itemscope itemtype="http://schema.org/ImageObject" itemprop="associatedMedia" data-slide-index="0" data-label-slug="fig-1"> <a class="figure-link" href="https://cdn.ncbi.nlm.nih.gov/pmc/blobs/a4d0/5776830/1d2f146c5ad0/pnas.1718063115fig01.jpg" itemprop="contentUrl" aria-describedby="figure-caption-0" role="button" data-image-width="757" data-image-height="546" data-image-alt="Fig. 1." data-pmc-id="PMC5776830" data-figure-id="fig01"> <img class="figure-thumb" itemprop="thumbnail" id="article-image-0" src="https://cdn.ncbi.nlm.nih.gov/pmc/blobs/a4d0/5776830/a8d874996d5d/pnas.1718063115fig01.gif" alt="Fig. 1." /> </a> <meta itemprop="width" itemtype="http://schema.org/ImageObject" content="757"> <meta itemprop="height" itemtype="http://schema.org/ImageObject" content="546"> <div class="figure-caption figure-caption-text" itemtype="http://schema.org/ImageObject" itemprop="caption" aria-hidden="true"> <div class="caption-wrap"> <strong class="figure-label"> <p> Fig. 1. </p> </strong> <div class="figure-caption-contents"><p> ( <i> A </i> – <i> N </i> )… </p></div> </div> </div> <div class="figure-caption-medium figure-caption-text" aria-hidden="true"> <strong class="figure-label"> <p> Fig. 1. </p> </strong> <div class="figure-caption-contents"><p> ( <i> A </i> – <i> N </i> ) Optical photomicrographs showing the locations of ( <i> B… </i> </p></div> </div> <figcaption id="figure-caption-0" class="figure-caption-full figure-caption-text" itemtype="http://schema.org/ImageObject" itemprop="description"> <strong class="figure-label"> Fig. 1. </strong> <div class="figure-caption-contents">(<i>A</i>–<i>N</i>) Optical photomicrographs showing the locations of (<i>B</i>–<i>D</i>, <i>F</i>, <i>G</i>, <i>I</i>–<i>N</i>) 11 specimens of five taxa of microfossils analyzed by SIMS embedded in clouds of flocculent organic matter permineralized in (<i>A</i>) petrographic thin section 4 of 6/15/82-1H of the ∼3,465 Ma Apex chert and (<i>E</i> and <i>H</i>) in its contained subrounded carbonaceous clasts. (<i>O</i>–<i>S</i>) Optical photomicrographs of (<i>O</i>) a similar clast and (<i>P</i>–<i>S</i>) filamentous microfossils in petrographic thin section 4 of 6/15/82-1B archived at London’s NMH (2). (<i>T</i>) 3D and (<i>U</i>–<i>Z</i>) 2D Raman images of the part of the specimen enclosed by the red rectangle in <i>S</i>. (<i>A</i>) Thin section 4 of 6/15/82–1H. (<i>B</i> and <i>C</i>) <i>A. disciformis</i> Schopf 1993 (specimens #G and #F, respectively). (<i>D</i>) <i>P. amoenum</i> Schopf 1992 (specimen #H). (<i>E</i>) Small clast. (<i>F</i>, <i>G</i>, and <i>K</i>) <i>P. minutum</i> Schopf 1993 (small clast specimens #2 and #3, and clast specimen #9, respectively). (<i>H</i>) Clast. (<i>I</i>, <i>J</i>, <i>L</i>, and <i>M</i>) <i>P. delicatulum</i> Schopf 1992 (clast specimens #11, #6, #4, and #5, respectively). (<i>N</i>) Unnamed unicell (clast specimen #12). (<i>O</i>) A subrounded carbonaceous clast. (<i>P</i>–<i>S</i>) Organic clast-enclosed specimens of <i>P. amoenum</i>, the arrows in <i>P</i> denoting their locations within the clast. (<i>T</i>–<i>Z</i>) Raman images (acquired in a spectral window centered on the kerogen “G” band at ∼1,605 cm<sup>−1</sup>) in which the 3D image in <i>T</i> has been rotated to show the cylindrical morphology of the filament and <i>U</i>–<i>Z</i> show 2D images at increasing depths through the specimen (<i>U</i>, 0.75 µm; <i>V</i>, 1.5 µm; <i>W</i>, 2.25 µm; <i>X</i>, 3.0 µm; <i>Y</i>, 3.75 µm; <i>Z</i>, 4.0 µm) that document its box-like kerogenous cell walls (arrows in <i>U</i>) and their enclosed cell lumina (arrows in <i>V</i>).</div> </figcaption> </figure> <figure class="figure-item " itemscope itemtype="http://schema.org/ImageObject" itemprop="associatedMedia" data-slide-index="1" data-label-slug="fig-2"> <a class="figure-link" href="https://cdn.ncbi.nlm.nih.gov/pmc/blobs/a4d0/5776830/ee9a71077f5d/pnas.1718063115fig02.jpg" itemprop="contentUrl" aria-describedby="figure-caption-1" role="button" data-image-width="762" data-image-height="287" data-image-alt="Fig. 2." data-pmc-id="PMC5776830" data-figure-id="fig02"> <img class="figure-thumb" itemprop="thumbnail" id="article-image-1" src="https://cdn.ncbi.nlm.nih.gov/pmc/blobs/a4d0/5776830/df9f59bb7e2a/pnas.1718063115fig02.gif" alt="Fig. 2." /> </a> <meta itemprop="width" itemtype="http://schema.org/ImageObject" content="762"> <meta itemprop="height" itemtype="http://schema.org/ImageObject" content="287"> <div class="figure-caption figure-caption-text" itemtype="http://schema.org/ImageObject" itemprop="caption" aria-hidden="true"> <div class="caption-wrap"> <strong class="figure-label"> <p> Fig. 2. </p> </strong> <div class="figure-caption-contents"><p> ( <i> A </i> , <i> C </i> ,… </p></div> </div> </div> <div class="figure-caption-medium figure-caption-text" aria-hidden="true"> <strong class="figure-label"> <p> Fig. 2. </p> </strong> <div class="figure-caption-contents"><p> ( <i> A </i> , <i> C </i> , <i> E </i> , <i> G </i> , <i> I </i> , <i> K </i> ,… </p></div> </div> <figcaption id="figure-caption-1" class="figure-caption-full figure-caption-text" itemtype="http://schema.org/ImageObject" itemprop="description"> <strong class="figure-label"> Fig. 2. </strong> <div class="figure-caption-contents">(<i>A</i>, <i>C</i>, <i>E</i>, <i>G</i>, <i>I</i>, <i>K</i>, <i>M</i>, <i>O</i>, <i>Q</i>, <i>S</i>, and <i>U</i>) Eleven specimens of five taxa of filamentous microfossils analyzed by SIMS in petrographic thin section 4 of 6/15/82-1H of the ∼3,465 Ma Apex chert shown in transmitted light photomicrographs and (<i>B</i>, <i>D</i>, <i>F</i>, <i>H</i>, <i>J</i>, <i>L</i>, <i>N</i>, <i>P</i>, <i>R</i>, <i>T</i>, and <i>V</i>) 2D Raman images that document the distribution of kerogen (blue, acquired in a spectral window centered on the kerogen “G” band at ∼1,605 cm<sup>−1</sup>). (<i>A</i>–<i>D</i>) <i>A. disciformis</i> Schopf 1993 (<i>A</i> and <i>B</i>, specimen #F; <i>C</i> and <i>D</i>, specimen #G). (<i>E</i>–<i>H</i>) <i>P. delicatulum</i> Schopf 1992 (<i>E</i> and <i>F</i>, clast specimen #4; <i>G</i> and <i>H</i>, clast specimen #5). (<i>I</i> and <i>J</i>) <i>P. amoenum</i> Schopf 1992 (specimen #H). (<i>K</i>–<i>N</i>) <i>P. delicatulum</i> Schopf 1992 (<i>K</i> and <i>L</i>, clast specimen #6; <i>M</i> and <i>N</i>, clast specimen #11). (<i>O</i>–<i>T</i>) <i>P. minutum</i> Schopf 1993 (<i>O</i> and <i>P</i>, clast specimen #9; <i>Q</i> and <i>R</i>, small clast specimen #2; <i>S</i> and <i>T</i>, small clast specimen #3). (<i>U</i> and <i>V</i>) Unnamed unicell (clast specimen #12).</div> </figcaption> </figure> <figure class="figure-item " itemscope itemtype="http://schema.org/ImageObject" itemprop="associatedMedia" data-slide-index="2" data-label-slug="fig-3"> <a class="figure-link" href="https://cdn.ncbi.nlm.nih.gov/pmc/blobs/a4d0/5776830/46ba4f6f204b/pnas.1718063115fig03.jpg" itemprop="contentUrl" aria-describedby="figure-caption-2" role="button" data-image-width="677" data-image-height="652" data-image-alt="Fig. 3." data-pmc-id="PMC5776830" data-figure-id="fig03"> <img class="figure-thumb" itemprop="thumbnail" id="article-image-2" src="https://cdn.ncbi.nlm.nih.gov/pmc/blobs/a4d0/5776830/c13a6fb99c53/pnas.1718063115fig03.gif" alt="Fig. 3." /> </a> <meta itemprop="width" itemtype="http://schema.org/ImageObject" content="677"> <meta itemprop="height" itemtype="http://schema.org/ImageObject" content="652"> <div class="figure-caption figure-caption-text" itemtype="http://schema.org/ImageObject" itemprop="caption" aria-hidden="true"> <div class="caption-wrap"> <strong class="figure-label"> <p> Fig. 3. </p> </strong> <div class="figure-caption-contents"><p> Paired images of pre-SIMS transmitted… </p></div> </div> </div> <div class="figure-caption-medium figure-caption-text" aria-hidden="true"> <strong class="figure-label"> <p> Fig. 3. </p> </strong> <div class="figure-caption-contents"><p> Paired images of pre-SIMS transmitted light photomicrographs (color) and post-SIMS SEM images (black… </p></div> </div> <figcaption id="figure-caption-2" class="figure-caption-full figure-caption-text" itemtype="http://schema.org/ImageObject" itemprop="description"> <strong class="figure-label"> Fig. 3. </strong> <div class="figure-caption-contents">Paired images of pre-SIMS transmitted light photomicrographs (color) and post-SIMS SEM images (black and white) of 11 specimens of five taxa of microfossils analyzed for δ<sup>13</sup>C in petrographic thin section 4 of 6/15/82-1H of the ∼3,465 Ma Apex chert. (<i>A</i> and <i>B</i>) Clast specimen #4; (<i>C</i> and <i>D</i>) clast specimens #5 and #6; (<i>E</i> and <i>F</i>) clast specimen #9; (<i>G</i> and <i>H</i>) clast specimen #11; (<i>I</i> and <i>J</i>) clast specimen #12; (<i>K</i> and <i>L</i>) specimen #F; (<i>M</i> and <i>N</i>) specimen #G (session-1); (<i>O</i> and <i>P</i>) specimen #G (session-2); (<i>Q</i> and <i>R</i>) specimen #H; (<i>S</i> and <i>T</i>) small clast specimen #2; and (<i>U</i> and <i>V</i>) small clast specimen #3. White circles in the photomicrographs indicate the locations of the SIMS-produced analytical pits. In the SEM images, <i>J</i> is a back-scattered electron image; all others are secondary electron images. These SEM images were acquired in sections veneered with a thin (<∼5-nm-thick) gold coat after removal of a thicker Au coat used during SIMS analyses and show the locations of analyzed spots having high (≥3 Mcps/nA) and marginally accepted (3 Mcps/nA to 1.5 Mcps/nA) <sup>12</sup>C yields. Not shown are carbon-poor analytical pits and SIMS-obtained δ<sup>13</sup>C measurements considered not to be reliable. See <i>Supporting Information</i> for additional analytical data. 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Cambridge Univ Press; New York: 1992. pp. 25–39. </li> </ol> </li> <li> <ol class="references-and-notes-list"> <li class="skip-numbering" value="1"> Schopf JW. Microfossils of the early Archean Apex chert: New evidence of the antiquity of life. Science. 1993;260:640–646. - <a class="reference-link" href="/11539831/" ref="linksrc=references_link&ordinalpos=1" data-ga-category="reference" data-ga-action="11539831" > PubMed </a> </li> </ol> </li> <li> <ol class="references-and-notes-list"> <li class="skip-numbering" value="1"> Moorbath S. Palaeobiology: Dating earliest life. Nature. 2005;434:155. - <a class="reference-link" href="/15758986/" ref="linksrc=references_link&ordinalpos=1" data-ga-category="reference" data-ga-action="15758986" > PubMed </a> </li> </ol> </li> <li> <ol class="references-and-notes-list"> <li class="skip-numbering" value="1"> Brasier MD, et al. Questioning the evidence for Earth’s oldest fossils. 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SIMS analyses of the oldest known assemblage of microfossils document their taxon-correlated carbon isotope compositions - PubMed