CINXE.COM

<!doctype html> <html lang="en" class="no-js">   <head> <meta content="IE=edge" http-equiv="X-UA-Compatible"> <title>Cambrian Period—541 to 485.4 MYA (U.S. National Park Service)</title> <script> var jsDlgLoader = '/articles/000/loader.cfm'; var jsSiteResourceLoader = '/cs-resources.cfm?r='; var jsSiteResourceSettings = {canCombine: false, canMinify: false}; </script>  <script src="/ADF/thirdParty/jquery/jquery-1.12.js"></script><script src="/commonspot/javascript/browser-all.js"></script>     <link rel="stylesheet" href="/common/commonspot/templates/assets/css/commonspotRTE.css" type="text/css" />   <script>  </script><script> var jsDlgLoader = '/articles/000/loader.cfm'; var jsSiteResourceLoader = '/cs-resources.cfm?r='; var jsSiteResourceSettings = {canCombine: false, canMinify: false}; </script>    <meta charset="utf-8"> <link href="/common/commonspot/templates/images/icons/favicon.ico" rel="shortcut icon"> <meta http-equiv="Pragma" content="no-cache" /> <meta http-equiv="Expires" content="0" /> <meta name="viewport" content="width=device-width, initial-scale=1.0">    <script src="/common/commonspot/templates/assets/js/app.early.min.js?v=20230112"></script> <link href="/common/commonspot/templates/assets/css/main.min.css?v=20230112" media="screen, print" rel="stylesheet">  <link href="/common/commonspot/templates/assets/ctExtraStyles.css?v=20230112" media="screen, print" rel="stylesheet"> <link href='//fonts.googleapis.com/css?family=Open+Sans:700,600,400|Open+Sans+Condensed:300,700' rel='stylesheet' type='text/css'> <link href="/common/commonspot/templates/assets/css/redesign.css?v=20230112" media="screen, print" rel="stylesheet"> <link rel="manifest" href="/manifest.json" crossorigin="use-credentials" /> <meta name="apple-itunes-app" content="app-id=1549226484, app-argument=https://apps.apple.com/us/app/national-park-service/id1549226484"> <style> table#cs_idLayout2, table#cs_idLayout2 > tbody, table#cs_idLayout2 > tbody > tr, table#cs_idLayout2 > tbody > tr > td { display: block; border-collapse:separate; } </style> <script src='/common/commonspot/templates/js/federated-analytics-uav1.js?ver=true&agency=DOI&subagency=NPS&exts=rtf,odt,ods,odp,brf&dclink=true&enhlink=true' id='_fed_an_ua_tag'></script> <meta property="og:type" content="website" /> <meta property="og:title" content="Cambrian Period—541 to 485.4 MYA (U.S. National Park Service)" /> <meta property="og:url" content="https://www.nps.gov/articles/000/cambrian-period.htm" />  <script async src="https://www.googletagmanager.com/gtag/js?id=UA-153506604-1"></script> <script> var current_url = window.location.href; if ( current_url.indexOf( 'www.nps.gov/dena/' ) > 0 ) { window.dataLayer = window.dataLayer || []; function gtag(){ dataLayer.push(arguments); } gtag('js', new Date()); gtag('config', 'UA-153506604-1', { 'anonymize_ip': true } ); gtag('config', 'UA-153506604-1', { 'optimize_id': 'GTM-5H7QTCC' } ); console.log( 'dena analytics script loaded for denali' ); } </script>    <meta property="og:image" content="https://www.nps.gov/articles/000/images/02-CAMBRIAN-SACN-BURROWS.JPG" /><meta property="og:image:height" content="2634" /><meta property="og:image:width" content="4127" /><meta property="og:image:alt" content="stone slab with fossil burrows" /><meta property="og:image" content="https://www.nps.gov/articles/000/images/paleozoic-banner.jpg" /><meta property="og:image:height" content="373" /><meta property="og:image:width" content="1439" /><meta property="og:image:alt" content="blue background with text paleozoic era 541 MILLION TO 252 MILLION YEARS AGO" />   <link rel="stylesheet" type="text/css" href="/commonspot/commonspot.css" id="cs_maincss">  </head><body class="SharedContent"><span role="navigation" aria-label="Top of page" id="__topdoc__"></span>  <div tabindex="-1" id="beforeSkipLinks" ></div> <div class="skip-links" aria-label="short-cut links" role="navigation"> <ul> <li><a href="#GlobalNav-toggle" aria-label="Skip to global NPS navigation">Skip to global NPS navigation</a></li> <li><a href="#main" aria-label="Skip to the main content">Skip to the main content</a></li> <li><a href="#GlobalFooter" aria-label="Skip to the footer section">Skip to the footer section</a></li> </ul> </div>   <div class="PromoBanner"></div>   <div class="GlobalHeader" role="banner"> <div class="GlobalHeader__Navbar container"> <a class="GlobalHeader__Branding me-auto link-white" href="/"> <img src="/theme/assets/dist/images/branding/logo.png" alt="" width="80" height="106" class="GlobalHeader__Branding__Arrowhead img-fluid"> <span class="GlobalHeader__Branding__Text"> National Park Service </span> </a> <a href="#GlobalFooterSearchInput" class="GlobalHeader__FooterSearchLink js-scrollTo link-white"> <i class="fa fa-search"></i> <span class="visually-hidden">Search</span> </a> <form id="GlobalHeaderSearch" class="GlobalHeader__Search" action="/search/" method="GET" role="search"> <button type="button" data-bs-toggle="collapse" data-bs-target="#GlobalHeaderSearchCollapse" aria-expanded="false" aria-controls="GlobalHeaderSearchCollapse"> <i class="fa fa-search"></i> Search </button> <div id="GlobalHeaderSearchCollapse" class="collapse collapse-horizontal" role="presentation"> <div> <input class="form-control me-2" type="text" autocomplete="off" name="query" placeholder="Keyword Search" required aria-label="Search text"> <div class="GlobalSearch-suggestions"></div> <button class="btn btn-secondary me-2" data-scope="site" type="submit"> This Site </button> <button class="btn btn-secondary" data-scope="all" type="submit"> All NPS </button> </div> </div> <input type="hidden" name="sitelimit" value="/"> <input type="hidden" name="affiliate" value="nps"> </form> </div> <nav id="GlobalNav" class="GlobalNav"> <h1 id="GlobalNavButtonContainer"> <button type="button" id="GlobalNav-toggle" class="GlobalNav__Toggle" data-bs-toggle="collapse" data-bs-target="#GlobalNavCollapse" aria-controls="GlobalNavCollapse" aria-expanded="false" aria-label="Open Menu"> <span class="GlobalNav__Toggle__Text GlobalNav__Toggle__Text--closed"> <i class="fa fa-bars"></i> <span class="visually-hidden">Open</span> Menu </span> <span class="GlobalNav__Toggle__Text GlobalNav__Toggle__Text--open"> <i class="fa fa-close"></i> Close <span class="visually-hidden">Menu</span> </span> </button> </h1> <div id="GlobalNavCollapse" class="collapse"> <div class="container"> <p class="GlobalNav__LanguageInfo"> </p> <h2 class="GlobalNav__SectionHeading GlobalNav__SectionHeading--green" hidden> Explore This Park </h2> <ul id="GlobalNavListLocal" class="GlobalNav__List" hidden></ul> <h2 class="GlobalNav__SectionHeading GlobalNav__SectionHeading--blue"> Explore the National Park Service </h2> <ul id="GlobalNavList" class="GlobalNav__List"></ul> </div> </div> </nav> </div>  <div id="myModal" class="modal refreshableModal" tabindex="-1" aria-labelledby="exitModalLabel" aria-hidden="true"> <div class="modal-dialog"> <div class="modal-content"> <div class="modal-header"> <h2 class="modal-title visually-hidden" id="exitModalLabel">Exiting nps.gov</h2> <button type="button" class="btn-close" data-bs-dismiss="modal" aria-label="Close"></button> </div> <div class="modal-body"></div> <div class="modal-footer"> <button type="button" class="btn btn-secondary" data-bs-dismiss="modal">Cancel</button> </div> </div> </div> </div> <script type="text/javascript"> jQuery(document).ready(function() { setTimeout( function() { NPS.display.showAdminTools( 0 ); } ,10); }); </script> <div id="main" role="main" class="MainContent"> <style> #modal-contact-us .modal-body { padding-top: 0px; } .modal-header { border:none; } </style> <div class="modal fade" id="modal-contact-us" tabindex="-1" aria-labelledby="modal-contact-us-label"> <div class="modal-dialog"> <div class="modal-content"> <div class="modal-header"> <h4 class="modal-title visually-hidden" id="modal-contact-us-label">Contact Us</h4> <button type="button" class="btn-close" data-bs-dismiss="modal" aria-label="Close"></button> </div> <div class="modal-body"> <iframe frameborder="0" id="modal-contact-us-iframe" width="100%" height="100%" title="Contact Us"></iframe> </div> </div> </div> </div> <div id="adminTools"></div> <div class="Article Article--Page container"> <header class="Article__Header"> <p class="Article__Kicker">Article</p> <h1 class="page-title">Cambrian Period—541 to 485.4 MYA</h1> </header> <div class="Article__Content"> <div id="cs_control_536382" class="cs_control CS_Element_Schedule"><div title="" id="CS_Element_contentcontainer"><div id="gridRow_1_1_536382" class="cs_GridRow"><div id="gridCol_1_1_1_1_536382" class="cs_GridColumn"><div id="cs_control_6577535" class="cs_control CS_Element_Custom"> <div class="Component InPageNav" id="97BCC451-C2D2-AE32-1DC2E5450EFD46DD-InPageNav"> <nav class="dropdown" aria-labelledby="97BCC451-C2D2-AE32-1DC2E5450EFD46DD-InPageNav-Title"> <button class="btn btn-light dropdown-toggle" id="97BCC451-C2D2-AE32-1DC2E5450EFD46DD-InPageNav-Title" type="button" data-bs-toggle="dropdown" data-tracking='{"type":"event","category":"PYV Component","action1":"Open","action2":"Close","label":"Navigation In Page"}' aria-expanded="false"> On This Page <span class="visuallyhidden">Navigation</span> </button> <ul class="dropdown-menu"></ul> </nav> </div> </div><div id="cs_control_6577509" class="cs_control CS_Element_Custom"><aside class="fact-check"> <h4>Cambrian Time Span</h4> <p><ul> <li><em>Date range: 541 million years ago to 485.4 million years ago</em></li> <li><em>Length: 55.6 million years (1.2% of geologic time)</em></li> <li><em>Geologic calendar: November 19–November 23 (Noon) (4 days, 12 hours)</em></li> </ul></p> </aside></div><div id="cs_control_6577514" class="cs_control CS_Element_Custom"><style>blockquote {border-left: 5px solid #fff;}</style> <div class="Component ArticleTextGroup TextWrapped clearfix"> <figure class="-auto-width"> <picture> <source type="image/webp" srcset="/articles/000/images/02-CAMBRIAN-SACN-BURROWS.JPG?maxwidth=1300&autorotate=false&quality=78&format=webp"> <img alt="stone slab with fossil burrows" src="/articles/000/images/02-CAMBRIAN-SACN-BURROWS.JPG?maxwidth=1300&autorotate=false" title="02 CAMBRIAN - SACN BURROWS" > </picture> <figcaption>Cambrian age fossil burrow, Saint Croix National Scenic Riverway. <p class="figcredit">NPS image</p></figcaption> </figure> <h2>Introduction</h2> <p>British geologists Adam Sedgwick and Roderick Impey Murchison studied the complex geology of western Wales. In 1835 both Sedgwick and Murchison named the rocks they studied for ancient Welsh tribes: Sedgwick used “Cambrian” and Murchison used “Silurian.” Each worker attempted to recognize breaks in the stratigraphic record as boundaries for his subdivision. Murchison began with the top of the sequence in the southeast; Sedgwick began at the base in the northwest. Murchison carefully documented the abundant fossils of these Silurian strata. Sedgwick’s strata were poorly fossiliferous, and his breakdown of the Cambrian System was essentially lithologic. When it became clear that their systems overlapped, a quarrel ensued because systems must be contiguous; that is, they do not overlap in time. The controversy was not resolved until 1879 when Charles Lapworth proposed the name “Ordovician System,” taken from another Welsh tribe, to include the disputed interval between Cambrian and Silurian. The Ordovician System rounded out the threefold paleontological division of the Early Paleozoic. The boundaries of Lapworth’s Ordovician System were based solely on its distinctive fossil content (Eicher 1976).<br /> <br /> Originally geologists defined the beginning of the Cambrian Period as the point where fossils appeared. Subsequently older fossils have been found, and this definition is no longer valid. Now the start of Cambrian time and end of the Precambrian is roughly determined to be the point at which numerous hard-shelled fossils first appeared.</p> <h2>Significant Cambrian events</h2> <p>In the latest Precambrian and Cambrian, the supercontinent Rodinia, which was centered about the South Pole, broke apart, and crustal blocks drifted northward. The largest fragment was Gondwana (a collection of today’s southern continents, including Antarctica, South America, Africa, Madagascar, Australia-New Guinea, and New Zealand, as well as Arabia and India, which are in the Northern Hemisphere today). The second-largest continent, Laurentia, included most of North America, though the southeastern United States was wedged between Africa and South America as part of Gondwana. Siberia (just south of the equator) and Baltica (Scandinavia, Eastern Europe, and Russia) were situated between Gondwana and Laurentia. The rest of Europe and much of what is present-day Asia was split into fragments along the north coast of Gondwana.<br /> <br /> The Cambrian Period marks an important point in the history of life on Earth; it is the time when many kinds of invertebrates and the first vertebrates—fishes—appeared in the fossil record. The <a href="http://www.ucmp.berkeley.edu/cambrian/burgess.html" id="http://www.ucmp.berkeley.edu/cambrian/burgess.html|">Burgess Shale</a> contains the best record of Cambrian animal fossils including soft-bodied forms. This locality reveals the presence of creatures originating from the “Cambrian explosion”—an evolutionary burst of animal origins dating from 545 to 525 million years ago. The “explosion” describes the very rapid proliferation of a truly amazing diversity of living things on Earth. Most of these creatures are now extinct and are known only from their fossils.<br /> <br /> During Cambrian time, life was only common in the water. The land was barren and subject to erosion; these geologic conditions led to mudslides, where sediment periodically rolled into the seas and buried marine organisms. At the Burgess Shale locality in the Canadian Rocky Mountains, sediment was deposited in a deep-water basin adjacent to an enormous algal reef with a vertical escarpment several hundred feet high. Though not in a U.S. national park, the type locality of the Burgess Shale—Burgess Pass—is located in British Columbia’s Yoho National Park. In order to protect the site, <a href="http://whc.unesco.org" id="http://whc.unesco.org|">UNESCO</a> designated the Burgess Shale as a world heritage site in 1981.</p> <h2>Explosion of life</h2> <p>The discovery of fossils from the Precambrian revealed that life evolved long before the Cambrian Period began. Nevertheless, two things make the Cambrian Period notable. First, life exploded with almost all the major groups evolving in a relatively short time (about 40 million years). Second, the rise of animals with hard shells meant they had a much better chance of becoming fossilized. The explosion of life in the Cambrian Period is particularly apparent in oceanic fauna, which was without precedent in Earth’s history. <br /> <br /> During the Cambrian, land plants had not yet evolved, so the terrestrial world was devoid of vegetation. However, in the oceans many marine invertebrates, including sponges and brachiopods (lamp shells), were present. Also, the first animals with backbones arose during the Cambrian: these were jawless fish called "a<em>gnathans".</em> They were strongly armored creatures with bony skeletons. Most of their fossil remains are pieces of bony exterior plates. Because they lacked biting jaws, they were probably bottom dwellers that fed by filter feeding. A few descendants of jawless fish survive today, for example, the lamprey “eel” (Macdougall 1996). <br /> <br /> Probably the best-known Cambrian animals were trilobites—a group of armored invertebrates that no longer exist. They were abundant in shallow Cambrian seas, which covered much of the world. Paleontologists have identified many species of Cambrian trilobites. Moreover, from the types of sediments in which the trilobites are fossilized, paleontologists have been able to determine something of their lifestyles. Trilobites included swimming forms; bottom dwellers; varieties that lived in warm, shallow waters; and those that lived in deeper, cooler regions. All species had hard, calcified external skeletons, which allowed them to be preserved in many Cambrian sedimentary rocks.<br /> <br /> As the Cambrian progressed, there was significant turnover in the animals. Groups that had appeared early in the Cambrian, such as reef-building sponges, many-limbed Anomalocaris and its relatives, and many others that are hard to place, dwindled or went extinct altogether. Life at the end of the Cambrian was relatively less diverse than earlier in the period.</p> </div></div><div id="cs_control_6577566" class="cs_control CS_Element_Custom"><style>blockquote {border-left: 5px solid #fff;}</style> <div class="Component ArticleTextGroup TextWrapped clearfix"> <h2>Visit—Cambrian Parks</h2> <p>Every park contains some slice of geologic time. Below, we highlight selected parks associated with the Cambrian Period. This is not to say that a particular park has only rocks from the specified period. Rather, rocks in selected parks exemplify a certain event or preserve fossils or rocks from a certain geologic age.</p> <ul> <li> <p>Chesapeake and Ohio Canal National Historical Park (CHOH), West Virginia, Washington D.C., and Maryland—[<a href="https://www.nps.gov/articles/nps-geodiversity-atlas-chesapeake-ohio-canal-national-historical-park-dc-md-and-wv.htm" id="CP___PAGEID=5756913,nps-geodiversity-atlas-chesapeake-ohio-canal-national-historical-park-dc-md-and-wv.htm,30335|">CHOH Geodiversity Atlas</a>] [<a href="https://www.nps.gov/choh/index.htm" id="CP___PAGEID=5655860,index.htm,16267|">CHOH Park Home</a>] [<a href="http://npshistory.com/publications/choh/index.htm" id="http://npshistory.com/publications/choh/index.htm|">CHOH npshistory.com</a>]</p> </li> <li> <p>Death Valley National Park, California (DEVA), Nevada—[<a href="https://www.nps.gov/articles/nps-geodiversity-atlas-death-valley-national-park-california-and-nevada.htm" id="CP___PAGEID=5830406,nps-geodiversity-atlas-death-valley-national-park-california-and-nevada.htm,30335|">DEVA Geodiversity Atlas</a>] [<a href="https://www.nps.gov/deva/index.htm" id="anch_26">DEVA Park Home</a>] [<a href="http://npshistory.com/publications/deva/index.htm" id="http://npshistory.com/publications/deva/index.htm|">DEVA npshistory.com</a>]</p> </li> <li> <p>Grand Canyon National Park (GRCA), Arizona—[<a href="https://www.nps.gov/articles/nps-geodiversity-atlas-grand-canyon-national-park-arizona.htm" id="CP___PAGEID=5835181,nps-geodiversity-atlas-grand-canyon-national-park-arizona.htm,30335|">GRCA Geodiversity Atlas</a>] [<a href="https://www.nps.gov/grca/index.htm" id="anch_39">GRCA Park Home</a>] [<a href="http://npshistory.com/publications/grca/index.htm" id="http://npshistory.com/publications/grca/index.htm|">GRCA npshistory.com</a>]</p> </li> <li> <p>Great Basin National Park (GRBA), Nevada—[<a href="https://www.nps.gov/articles/nps-geodiversity-atlas-great-basin-national-park.htm" id="CP___PAGEID=5643545,nps-geodiversity-atlas-great-basin-national-park.htm,30335|">GRBA Geodiversity Atlas</a>] [<a href="https://www.nps.gov/grba/index.htm" id="CP___PAGEID=481984,index.htm,552|">GRBA Park Home</a>] [<a href="http://npshistory.com/publications/grba/index.htm" id="http://npshistory.com/publications/grba/index.htm|">GRBA npshistory.com</a>]</p> </li> <li> <p>Great Smoky Mountains National Park (GRSM), Tennessee and North Carolina—[<a href="https://www.nps.gov/articles/nps-geodiversity-atlas-great-smoky-mountains-national-park.htm" id="https://www.nps.gov/articles/nps-geodiversity-atlas-great-smoky-mountains-national-park.htm|">GRSM Geodiversity Atlas</a>] [<a href="https://www.nps.gov/grsm/index.htm" id="https://www.nps.gov/grsm/index.htm|">GRSM Park Home</a>] [<a href="http://npshistory.com/publications/grsm/index.htm" id="http://npshistory.com/publications/grsm/index.htm|">GRSM npshistory.com</a>]</p> </li> <li> <p>Harpers Ferry National Historical Park (HAFE), Maryland, Virginia, and West Virginia—[<a href="https://www.nps.gov/articles/nps-geodiversity-atlas-harpers-ferry-national-historical-park-west-virginia-virginia-and-maryland.htm" id="CP___PAGEID=5787496,nps-geodiversity-atlas-harpers-ferry-national-historical-park-west-virginia-virginia-and-maryland.htm,30335|">HAFE Geodiversity Atlas</a>] [<a href="https://www.nps.gov/hafe/index.htm" id="CP___PAGEID=2871583,index.htm,16165|">HAFE Park Home</a>] [<a href="http://npshistory.com/publications/hafe/index.htm" id="http://npshistory.com/publications/hafe/index.htm|">npshistory.com</a>]</p> </li> <li> <p>Saint Croix National Scenic Riverway (SACN), Minnesota and Wisconsin—[<a href="https://www.nps.gov/articles/nps-geodiversity-atlas-saint-croix-national-scenic-river-wisconsin-and-minnesota.htm" id="CP___PAGEID=5845119,nps-geodiversity-atlas-saint-croix-national-scenic-river-wisconsin-and-minnesota.htm,30335|">SACN Geodiversity Atlas</a>] [<a href="https://www.nps.gov/sacn/index.htm" id="CP___PAGEID=3267538,index.htm,21825|">SACN Park Home</a>] [<a href="http://npshistory.com/publications/sacn/index.htm" id="http://npshistory.com/publications/sacn/index.htm|">SACN npshistory.com</a>]</p> </li> <li> <p>Yellowstone National Park (YELL), Idaho, Montana, and Wyoming—[<a href="https://www.nps.gov/articles/nps-geodiversity-atlas-yellowstone-national-park-wyoming-montana-and-idaho.htm" id="CP___PAGEID=5855828,nps-geodiversity-atlas-yellowstone-national-park-wyoming-montana-and-idaho.htm,30335|">YELL Geodiversity Atlas</a>] [<a href="https://www.nps.gov/yell/index.htm" id="anch_34">YELL Park Home</a>] [<a href="http://npshistory.com/publications/yell/index.htm" id="http://npshistory.com/publications/yell/index.htm|">YELL npshistory.com</a>]</p> </li> <li> <p>Yukon-Charley Rivers National Park (YUCH), Alaska—[<a href="https://www.nps.gov/articles/nps-geodiversity-atlas-yukon-charley-rivers-national-preserve-alaska.htm" id="CP___PAGEID=5855829,nps-geodiversity-atlas-yukon-charley-rivers-national-preserve-alaska.htm,30335|">YUCH Geodiversity Atlas</a>] [<a href="https://www.nps.gov/YUCH/index.htm" id="https://www.nps.gov/YUCH/index.htm|">YUCH Park Home</a>] [<a href="http://npshistory.com/publications/yuch/index.htm" id="http://npshistory.com/publications/yuch/index.htm|">YUCH npshistory.com</a>]</p> </li> </ul> </div></div><div id="cs_control_6577568" class="cs_control CS_Element_Custom"><style>blockquote {border-left: 5px solid #fff;}</style> <div class="Component ArticleTextGroup TextWrapped clearfix"> <h2>More about the Paleozoic</h2> </div></div><div id="cs_control_6577532" class="cs_control CS_Element_Custom"><style>blockquote {border-left: 5px solid #fff;}</style> <div class="Component ArticleTextGroup TextWrapped clearfix"> <figure class="-auto-width"> <a href="/articles/000/paleozoic-era.htm"> <picture> <source type="image/webp" srcset="/articles/000/images/paleozoic-banner.jpg?maxwidth=1300&autorotate=false&quality=78&format=webp"> <img alt="blue background with text paleozoic era 541 MILLION TO 252 MILLION YEARS AGO" src="/articles/000/images/paleozoic-banner.jpg?maxwidth=1300&autorotate=false" title="paleozoic banner" > </picture> </a> </figure> </div></div><div id="cs_control_6597727" class="cs_control CS_Element_Custom"><style>blockquote {border-left: 5px solid #fff;}</style> <div class="Component ArticleTextGroup TextWrapped clearfix"> <h2><span style="color:#ffffff;">►</span></h2> </div></div><div id="cs_control_6607405" class="cs_control CS_Element_Custom"><style>blockquote {border-left: 5px solid #fff;}</style> <div class="Component ArticleTextGroup TextWrapped clearfix"> <div class="panel panel-default collapsible-item" id="Collapsible1599751730792"> <div class="panel-heading collapsible-item-heading" id="headingCollapsible1599751730792" role="tab"> <h4 class="panel-title collapsible-item-title"><a aria-controls="collapseCollapsible1599751730792" aria-expanded="false" aria-hidden="true" class="collapsed collapsible-item-title-link-icon pull-right" data-toggle="collapse" href="#collapseCollapsible1599751730792" role="button"><span class="glyphicon glyphicon-chevron-down"> </span></a> <a aria-controls="collapseCollapsible1599751730792" aria-expanded="false" class="collapsed collapsible-item-title-link" data-toggle="collapse" href="#collapseCollapsible1599751730792" role="button"><span>Fossils Through Geologic Time—Site Index</span></a></h4> </div> <div aria-labelledby="headingCollapsible1599751730792" class="panel-collapse collapse collapsible-item-collapse" id="collapseCollapsible1599751730792" role="tabpanel"> <div class="panel-body collapsible-item-body"> <p><a href="/subjects/fossils/fossils-through-geologic-time.htm" id="CP___PAGEID=5083177,fossils-through-geologic-time.htm,30399|">Fossils Through Geologic Time</a><br /> <br /> <a href="/articles/000/cenozoic-era.htm" id="CP___PAGEID=6559686,cenozoic-era.htm,31093|">> Ceonzoic</a></p> <ul> <li><a href="/articles/000/quaternary-period.htm" id="CP___PAGEID=6582611,/articles/000/quaternary-period.htm,31093|" onmouseout="" onmouseover="">Quaternary: 2.58 to 0 MYA</a></li> <li> <p><a href="/articles/000/neogene-period.htm" id="CP___PAGEID=6582612,/articles/000/neogene-period.htm,31093|" onmouseout="" onmouseover="">Neogene: 23.0 to 2.58 MYA</a></p> </li> <li><a href="/articles/000/paleogene-period.htm" id="CP___PAGEID=6582613,/articles/000/paleogene-period.htm,31093|" onmouseout="" onmouseover="">Paleogene: 66.0 to 23.0 MYA</a></li> </ul> <p><a href="/articles/000/mesozoic-era.htm" id="CP___PAGEID=6559670,mesozoic-era.htm,31093|">> Mesozoic</a></p> <ul> <li> <p><a href="/articles/000/cretaceous-period.htm" id="CP___PAGEID=6582462,/articles/000/cretaceous-period.htm,31093|" onmouseout="" onmouseover="">Cretaceous: 145.0 to 66.0 MYA</a></p> </li> <li> <p><a href="/articles/000/jurassic-period.htm" id="CP___PAGEID=6582464,/articles/000/jurassic-period.htm,31093|" onmouseout="" onmouseover="">Jurassic: 201.3 to 145.0 MYA</a></p> </li> <li> <p><a href="/articles/000/triassic-period.htm" id="CP___PAGEID=6582469,/articles/000/triassic-period.htm,31093|" onmouseout="" onmouseover="">Triassic: 251.9 to 201.3 MYA</a></p> </li> </ul> <p><a href="/articles/000/paleozoic-era.htm" id="CP___PAGEID=6559592,paleozoic-era.htm,31093|">> Paleozoic</a></p> <ul> <li> <p><a href="/articles/000/permian-period.htm" id="CP___PAGEID=6582310,permian-period.htm,31093|">Permian: 298.9 to 251.9 MYA</a></p> </li> <li> <p><a href="/articles/000/pennsylvanian-period.htm" id="CP___PAGEID=6582313,pennsylvanian-period.htm,31093|">Pennsylvanian: 323.2 to 298.9 MYA</a></p> </li> <li> <p><a href="/articles/000/mississippian-period.htm" id="CP___PAGEID=6582315,mississippian-period.htm,31093|">Mississippian: 358.9 to 323.2 MYA</a></p> </li> <li> <p><a href="/articles/000/devonian-period.htm" id="CP___PAGEID=6582317,devonian-period.htm,31093|">Devonian: 419.2 to 358.9 MYA</a></p> </li> <li> <p><a href="/articles/000/silurian-period.htm" id="CP___PAGEID=6582309,silurian-period.htm,31093|">Silurian: 443.8 to 419.2 MYA</a></p> </li> <li> <p><a href="/articles/000/ordovician-period.htm" id="CP___PAGEID=6577795,ordovician-period.htm,31093|">Ordovician: 485.4 to 443.8 MYA</a></p> </li> <li> <p><a href="/articles/000/cambrian-period.htm" id="CP___PAGEID=6577507,cambrian-period.htm,31093|">Cambrian: 541 to 485.4 MYA</a></p> </li> </ul> <p><a href="/articles/000/the-precambrian.htm" id="CP___PAGEID=6559566,the-precambrian.htm,31093|">> Precambrian</a></p> <ul> <li><a href="https://www.nps.gov/articles/000/proterozoic-eon.htm" id="https://www.nps.gov/articles/000/proterozoic-eon.htm|">Proterozoic: 2.5 Billion to 541 MYA</a></li> </ul> </div> </div> </div> </div></div></div></div></div></div> </div> <div id="cs_control_4826340" class="cs_control CS_Element_Custom"> <script> var siteCodeArr = "CHOH,DEVA,GRCA,GRBA,GRSM,HAFE,SACN,YELL,YUCH".split(","); for (i = 0; i < siteCodeArr.length; i++) { setTimeout(gasFunction(siteCodeArr[i]), 1000); function gasFunction(x) { gas('send', 'event', 'Shared Content', x, window.location.href, 0, true); } } </script> <script> var siteCodeArr = "/ORGS/1088".split(","); for (i = 0; i < siteCodeArr.length; i++) { setTimeout(gasFunction(siteCodeArr[i]), 1000); function gasFunction(x) { gas('send', 'event', 'Shared Content', x, window.location.href, 0, true); } } </script> <div class="Article__SeriesNav text-content-style"> <p> Part of a series of articles titled <a href="/articles/series.htm?id=90B58907-A98B-40CE-3A0F7CF9E150C190" class="Article__SeriesNav__Title" >Geologic Time Periods in the Paleozoic Era</a>. </p> <div class="row"> <div class="col-sm-6 Article__SeriesNav__Control"> <p> <span class="Article__SeriesNav__ControlLabel">Previous:</span> <a href="/articles/000/ordovician-period.htm" >Ordovician Period—485.4 to 443.8 MYA</a> </p> </div> <div class="col-sm-6 Article__SeriesNav__Control"> </div> </div> </div>  <div class="Component RelatedGrid" id="related_97BD59A2-E9CD-0690-050E1EBAB68945C4" style="display:none;"> <h2 class="RelatedGrid__Heading Tag">You Might Also Like</h2> <div class="row"> </div> <div class="row"> </div> <script src="/common/commonspot/customcf/search/js/search-listing-page-plugin.js"></script> <script> jQuery(document).ready(function() { jQuery('#searchListing-97BD59F8-E220-1E23-4A710F37A0A1D568').searchlisting({ searchURL: "/solr/", searchURLReady: "/solr/?q=\"fossils\" OR \"paleontology\" OR \"geology\" OR \"geologic time\"&fl=PageURL,Title,Type,Image_URL,Image_Alt_Text,PageURL&defType=edismax&sort=score desc&start=0&fq=Category:\"Articles\" AND (Type:\"Article\" OR Type:\"Person\" OR Type:\"Place\") AND -PageURL:\"/articles/000/cambrian-period.htm\" AND -Allow_Listing_Display:false AND (Image_Width:[465 TO *] AND Image_Height:[261 TO *]) OR (Original_Image_Width:[465 TO *] AND Original_Image_Height:[261 TO *])&rows=6", getMetaFields: "PageURL,Title,Type,Image_URL,Image_Alt_Text,PageURL", frontEndClient: "", perPage: "6", startNum: "0", keywords: "\"fossils\" OR \"paleontology\" OR \"geology\" OR \"geologic time\"", filterQuery: "Category:\"Articles\" AND (Type:\"Article\" OR Type:\"Person\" OR Type:\"Place\") AND -PageURL:\"/articles/000/cambrian-period.htm\" AND -Allow_Listing_Display:false AND (Image_Width:[465 TO *] AND Image_Height:[261 TO *]) OR (Original_Image_Width:[465 TO *] AND Original_Image_Height:[261 TO *])", usesDynamicNavigation: "", sort: "score desc", extrasForm: "", extrasForm_keywordField: "", dataTransformJS: "" ,showSearchResultsLIOverride: function(item){ var itemHTML = ""; var meta = []; jQuery.each(item, function (index, value) { meta[index] = value; }); //determine big or small var itemCount = jQuery("#related_97BD59A2-E9CD-0690-050E1EBAB68945C4 div.RelatedGridItem").length; if(itemCount < 4){ var mainDivClass = "col-xs-6 col-sm-3"; if(meta["Image_URL"].indexOf('/npgallery') !== -1){ var srcSet = meta["Image_URL"] + "/proxylowres"; }else{ var srcSet = meta["Image_URL"] + "?width=465&height=261&mode=crop&quality=90 465w"; } var childToUse = 0; var utmContent = "small"; }else{ var mainDivClass = "col-sm-6"; if(meta["Image_URL"].indexOf('/npgallery') !== -1){ var srcSet = meta["Image_URL"] + "/proxylowres 465w, " + meta["Image_URL"] + "/proxylowres 950w"; }else{ var srcSet = meta["Image_URL"] + "?width=465&height=261&mode=crop&quality=90 465w, " + meta["Image_URL"] + "?width=950&height=534&quality=90 950w"; } var childToUse = 1; var utmContent = "large"; } var url = meta["PageURL"]; if("Type" in meta) { if (url.indexOf("?") == -1) { url += "?utm_source=" + meta["Type"].toString().toLowerCase() + "&utm_medium=website&utm_campaign=experience_more&utm_content=" + utmContent; } else { url += "&utm_source=" + meta["Type"].toString().toLowerCase() + "&utm_medium=website&utm_campaign=experience_more&utm_content=" + utmContent; } } //URL plus campaign tracking if(meta["Image_URL"].indexOf('/npgallery') !== -1){ var src = meta["Image_URL"] + "/proxylowres"; }else{ var src = meta["Image_URL"] + "?width=465&height=261&mode=crop&quality=90"; } itemHTML += '<div class="Component RelatedGridItem ' + mainDivClass + '">'; itemHTML += '<a href="'+url+'" class="RelatedGridItem__Link" data-track={"type":"event","category":"Navigate","action":"#","label":"RelatedGridItem"}>'; itemHTML += '<img alt="' + meta["Image_Alt_Text"] + '" class="RelatedGridItem__Image" sizes="(min-width: 1200px) 220px, (min-width: 768px) 25vw, 100vw" src="' + src + '" srcset="' + srcSet + '" />'; itemHTML += '<h3 class="RelatedGridItem__Heading">' + meta["Title"] + ' <i class="fa fa-chevron-right"></i></h3>'; itemHTML += '<div class="RelatedGridItem__Kicker">' + meta["Type"] + '</div>'; itemHTML += '</a></div>'; jQuery("#related_97BD59A2-E9CD-0690-050E1EBAB68945C4").children("div").eq(childToUse).append(itemHTML); } ,runFunctionAfter: function(){ if(jQuery("#related_97BD59A2-E9CD-0690-050E1EBAB68945C4 div.RelatedGridItem").length > 0){ jQuery(this.element).parent().show(); } } }) }); </script> <div id="searchListing-97BD59F8-E220-1E23-4A710F37A0A1D568"> <div> <div> <div class="results"> <a name="results"></a> <div class="loadingResultsMsg"> Loading results... </div> <ul class="resultsUL"></ul> </div> </div> </div> </div> </div>  <div class="SharedContentTags"> <h2 class="SharedContentTags__Heading Tag"> <i class="fa fa-tag"></i> Tags </h2> <ul> <li> <a class="btn btn-default" href="https://www.nps.gov/media/article-search.htm#fq[]=Sites_Item:"Chesapeake+%26+Ohio+Canal+National+Historical+Park"">chesapeake & ohio canal national historical park</a> </li> <li> <a class="btn btn-default" href="https://www.nps.gov/media/article-search.htm#fq[]=Sites_Item:"Death+Valley+National+Park"">death valley national park</a> </li> <li> <a class="btn btn-default" href="https://www.nps.gov/media/article-search.htm#fq[]=Sites_Item:"Grand+Canyon+National+Park"">grand canyon national park</a> </li> <li> <a class="btn btn-default" href="https://www.nps.gov/media/article-search.htm#fq[]=Sites_Item:"Great+Basin+National+Park"">great basin national park</a> </li> <li> <a class="btn btn-default" href="https://www.nps.gov/media/article-search.htm#fq[]=Sites_Item:"Great+Smoky+Mountains+National+Park"">great smoky mountains national park</a> </li> <li> <a class="btn btn-default" href="https://www.nps.gov/media/article-search.htm#fq[]=Sites_Item:"Harpers+Ferry+National+Historical+Park"">harpers ferry national historical park</a> </li> <li> <a class="btn btn-default" href="https://www.nps.gov/media/article-search.htm#fq[]=Sites_Item:"Saint+Croix+National+Scenic+Riverway"">saint croix national scenic riverway</a> </li> <li> <a class="btn btn-default" href="https://www.nps.gov/media/article-search.htm#fq[]=Sites_Item:"Yellowstone+National+Park"">yellowstone national park</a> </li> <li> <a class="btn btn-default" href="https://www.nps.gov/media/article-search.htm#fq[]=Sites_Item:"Yukon+-+Charley+Rivers+National+Preserve"">yukon - charley rivers national preserve</a> </li> <li> <a class="btn btn-default" href="https://www.nps.gov/media/article-search.htm#q=fossils">fossils</a> </li> <li> <a class="btn btn-default" href="https://www.nps.gov/media/article-search.htm#q=paleontology">paleontology</a> </li> <li> <a class="btn btn-default" href="https://www.nps.gov/media/article-search.htm#q=geology">geology</a> </li> <li> <a class="btn btn-default" href="https://www.nps.gov/media/article-search.htm#q=geologic+time">geologic time</a> </li> </ul> </div> <div style="display: none"> <p class="RelatedParksSubtitle"> <a href="/choh/">Chesapeake & Ohio Canal National Historical Park</a>, <a href="/deva/">Death Valley National Park</a>, <a href="/grca/">Grand Canyon National Park</a>, <a href="/grba/">Great Basin National Park</a>, <a href="/grsm/">Great Smoky Mountains National Park</a>, <span id="RelatedParksSubtitleHidden"> <a href="/hafe/">Harpers Ferry National Historical Park</a>, <a href="/sacn/">Saint Croix National Scenic Riverway</a>, <a href="/yell/">Yellowstone National Park</a>, <a href="/yuch/">Yukon - Charley Rivers National Preserve</a> </span> <i><a id="RelatedParksSubtitleControl" href="#" role="button">more »</a></i> </p> <script> jQuery(document).ready(function () { var moreLink = jQuery('#RelatedParksSubtitleControl'); var moreContent = jQuery('#RelatedParksSubtitleHidden'); moreLink.attr({ 'aria-expanded': false, 'aria-controls': 'RelatedParksSubtitleHidden' }); moreContent.hide(); moreLink.on('click', function (e) { e.preventDefault(); if (moreLink.attr('aria-expanded') === 'true') { moreLink.html('more »'); moreLink.attr('aria-expanded', false); moreContent.hide(); } else { moreLink.html('« less'); moreLink.attr('aria-expanded', true); moreContent.show(); } }); }); </script> </div> <script> (function ($) { $(document).ready(function () { var header = document.querySelector('.Article__Header'); var kicker = document.querySelector('.Article__Kicker'); var relatedParksSubtitle = document.querySelector('.RelatedParksSubtitle'); var seriesTitle = `Geologic Time Periods in the Paleozoic Era`; if (relatedParksSubtitle) { if (header) { header.appendChild(relatedParksSubtitle); } else { relatedParksSubtitle.remove(); } } if (kicker && seriesTitle) { var seriesKicker = document.createElement('span'); seriesKicker.innerHTML = ' • '; seriesKicker.appendChild(document.createTextNode(seriesTitle)); kicker.appendChild(seriesKicker); } }); })(jQuery); </script> </div> </div> <div class="container"> <div class="ColumnGrid row"> <div class="ColumnMain col-sm-12"> <div class="row"> <div class="col-sm-12 text-content-size text-content-style"> <p style="text-align:right;">Last updated: January 22, 2025</p> </div> </div> </div> </div> </div> </div>  <footer id="GlobalFooter" class="GlobalFooter"> <div class="container"> <form id="GlobalFooterSearch" class="GlobalFooter__Search row g-3 align-items-center" action="/search/" method="GET" role="search"> <div class="col-auto flex-grow-1 position-relative"> <input class="form-control" id="GlobalFooterSearchInput" type="text" autocomplete="off" name="query" placeholder="Keyword Search" required aria-label="Search"> <div class="GlobalSearch-suggestions"></div> </div> <div class="col-auto"> <button class="btn btn-secondary" data-scope="site" type="submit"> This Site </button> </div> <div class="col-auto"> <button class="btn btn-secondary" data-scope="all" type="submit"> All NPS </button> </div> <input type="hidden" name="sitelimit" value="/"> <input type="hidden" name="affiliate" value="nps"> </form> <div class="row"> <img class="GlobalFooter-printLogo print-only" src="/common/commonspot/templates/assets/images/branding/nps_logo-bw.gif" alt=""> <div class="col-sm-12"> <div class="GlobalFooter-AppPromo"> <div class="GlobalFooter-AppPromo__Text"> <div class="GlobalFooter-AppPromo__Heading">Experience Your America.</div> <div class="GlobalFooter-AppPromo__Subheading GlobalFooter-AppPromo__BottomGroup"> <p>Download the NPS app to navigate the parks on the go.</p> <p class="GlobalFooter-AppPromo__BadgeLinks"> <a href="https://apps.apple.com/us/app/national-park-service/id1549226484" class="GlobalFooter-AppPromo__BadgeLink" onclick="gas('send', 'event', 'App Promo Footer', 'Apple', document.location.pathname, 1, true);"> <img alt="Download on the App Store" src="/common/commonspot/templates/assets/images/app-promo/app-store-badge.svg" width="132" height="44"> </a> <a href="https://play.google.com/store/apps/details?id=gov.nps.mobileapp" class="GlobalFooter-AppPromo__BadgeLink" onclick="gas('send', 'event', 'App Promo Footer', 'Android', document.location.pathname, 1, true);"> <img alt="Get it on Google Play" src="/common/commonspot/templates/assets/images/app-promo/google-play-badge.svg" width="148.5" height="44"> </a> </p> </div> </div> <div class="GlobalFooter-AppPromo__ImageContainer"> <img class="GlobalFooter-AppPromo__Image" src="/common/commonspot/templates/assets/images/app-promo/app-promo-phones.png" srcset="/common/commonspot/templates/assets/images/app-promo/app-promo-phones.png 1x, /common/commonspot/templates/assets/images/app-promo/app-promo-phones@2x.png 2x" alt="Three smartphones showing different screens within the NPS app." width="628" height="463"> </div> </div> </div> </div> <hr> <div class="row"> <div class="col-xs-12 col-md-4 order-md-1"> <div class="GlobalFooter-nps-logo"> <div class="GlobalFooter-nps-logo-text"> <a href="//www.nps.gov">National Park Service</a> <a href="//www.doi.gov">U.S. Department of the Interior</a> </div> <div class="GlobalFooter-nps-logo-image"> <a href="//www.nps.gov"> <svg class="" id="nps-logo-footer" aria-label="National Park Service Logo" role="img" focusable="false"> <use xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="/common/commonspot/templates/assets/sprite.symbol.svg#nps-logo" /> </svg> </a> </div> </div> </div> <div class="col-xs-12 col-md-8"> <ul class="GlobalFooter-generalLinks"> <li> <a href="//www.nps.gov/aboutus/accessibility.htm" > Accessibility </a> </li> <li> <a href="//www.nps.gov/aboutus/privacy.htm" > Privacy Policy </a> </li> <li> <a href="//www.nps.gov/aboutus/foia/index.htm" > FOIA </a> </li> <li> <a href="//www.nps.gov/aboutus/notices.htm" > Notices </a> </li> <li> <a href="//www.nps.gov/aboutus/contactus.htm" > Contact The National Park Service </a> </li> </ul> <ul class="GlobalFooter-generalLinks"> <li> <a href="//www.nps.gov/aboutus/faqs.htm" title="National Park Service frequently asked questions"> NPS FAQ </a> </li> <li> <a href="//www.doi.gov/pmb/eeo/no-fear-act" > No Fear Act </a> </li> <li> <a href="//www.nps.gov/aboutus/disclaimer.htm" > Disclaimer </a> </li> <li> <a href="//www.nps.gov/aboutus/vulnerability-disclosure-policy.htm" > Vulnerability Disclosure Policy </a> </li> <li> <a href="//www.usa.gov" > USA.gov </a> </li> </ul> <ul class="GlobalFooter-socialLinks"> <li> <a href="//www.facebook.com/nationalparkservice"> <svg class="" id="facebook-footer-link" aria-label="Facebook" role="img" focusable="false"> <use xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="/common/commonspot/templates/assets/sprite.symbol.svg#facebook" /> </svg> </a> </li> <li> <a href="//www.youtube.com/nationalparkservice"> <svg class="" id="youtube-footer-link" aria-label="Youtube" role="img" focusable="false"> <use xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="/common/commonspot/templates/assets/sprite.symbol.svg#youtube" /> </svg> </a> </li> <li> <a href="//www.x.com/natlparkservice"> <svg class="" id="twitter-footer-link" aria-label="Twitter" role="img" focusable="false"> <use xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="/common/commonspot/templates/assets/sprite.symbol.svg#x-white" /> </svg> </a> </li> <li> <a href="//www.instagram.com/nationalparkservice"> <svg class="" id="instagram-footer-link" aria-label="Instagram" role="img" focusable="false"> <use xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="/common/commonspot/templates/assets/sprite.symbol.svg#instagram" /> </svg> </a> </li> <li> <a href="//www.flickr.com/nationalparkservice"> <svg class="" id="flickr-footer-link" aria-label="Flickr" role="img" focusable="false"> <use xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="/common/commonspot/templates/assets/sprite.symbol.svg#flickr" /> </svg> </a> </li> </ul> </div> </div> </div> </footer>   <script src="/common/commonspot/templates/js/global.js?v=20230112"></script> <script src="/common/commonspot/templates/assets/libs/jquery.magnific-popup/jquery.magnific-popup.js"></script> <script src="/common/commonspot/templates/assets/js/redesign.js?v=20230112"></script> <link href="/common/commonspot/templates/assets/libs/colorbox/colorbox.css" rel="stylesheet"> <script type="text/javascript" src="/common/commonspot/templates/js/libs/jquery.colorbox-min.js"></script> <script src="/common/commonspot/templates/js/intercept-include.js?v=20230112"></script> <script src="/common/commonspot/templates/assets/libs/image-map-resizer/imageMapResizer.min.js"></script> <script src="/common/commonspot/templates/assets/js/app.late.min.js?v=20230112"></script> <div class="modal fade" id="outdated-browser" tabindex="-1" role="dialog"> </div> </body> </html>  <script src="/commonspot/javascript/lightbox/overrides.js"></script><script src="/commonspot/javascript/lightbox/window_ref.js"></script><script src="/commonspot/pagemode/always-include-common.js"></script>   <script src="/ADF/thirdParty/jquery/cookie/jquery.cookie.js"></script>     <script>  </script> <script>  </script> </body></html>