{"id":25672,"date":"2020-05-05T05:54:59","date_gmt":"2020-05-05T05:54:59","guid":{"rendered":"https:\/\/www.bgs.ac.uk\/?page_id=25672"},"modified":"2021-09-09T13:09:38","modified_gmt":"2021-09-09T13:09:38","slug":"graptolites","status":"publish","type":"page","link":"https:\/\/www.bgs.ac.uk\/discovering-geology\/fossils-and-geological-time\/graptolites\/","title":{"rendered":"Graptolites"},"content":{"rendered":"\t\t\t<section class=\"hero-section hero-section-with-social\">\n\t\t\t\t\t\t\t\t<div class=\"hero-info-wrap\">\n\t\t\t\t\t<div class=\"container\">\n\t\t\t\t\t\t<div class=\"row\">\n\t\t\t\t\t\t\t<div class=\"col-12\">\n\t\t\t\t\t\t\t\t<div class=\"hero-info\">\n\t\t\t\t\t\t\t\t\t<h1>Graptolites<\/h1>\n\t\t\t\t\t\t\t\t\t<p>Discovering Geology &mdash; Fossils and geological time<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\n\t\t\t<div class=\"social-wrap social-wrap-inline-them\">\n\t\t\t\t<div class=\"sea-background-f\">\n\t\t\t\t\t<span>Share this article<\/span><a target=\"_blank\"  href=\"https:\/\/www.facebook.com\/sharer\/sharer.php?u=https:\/\/www.bgs.ac.uk\/discovering-geology\/fossils-and-geological-time\/graptolites\/\"><span class=\"icon-facebook\"><span class=\"hidden\">Facebook<\/span><\/span><\/a><a target=\"_blank\"  href=\"https:\/\/twitter.com\/intent\/tweet?text=Graptolites&#038;url=https:\/\/www.bgs.ac.uk\/discovering-geology\/fossils-and-geological-time\/graptolites\/\"><span class=\"icon-twitter\"><span class=\"hidden\">Twitter<\/span><\/span><\/a><a   onclick=\"javascript:void( (function() {var e=document.createElement('script' );e.setAttribute('type','text\/javascript' );e.setAttribute('charset','UTF-8' );e.setAttribute('src','\/\/assets.pinterest.com\/js\/pinmarklet.js?r='+Math.random()*99999999);document.body.appendChild(e)})());\"  href=\"javascript:void(0);\"><span class=\"icon-pinterest\"><span class=\"hidden\">Pinterest<\/span><\/span><\/a><a target=\"_blank\"  href=\"https:\/\/wa.me?text=https:\/\/www.bgs.ac.uk\/discovering-geology\/fossils-and-geological-time\/graptolites\/\"><span class=\"icon-whatsapp\"><span class=\"hidden\">WhatsApp<\/span><\/span><\/a><a   href=\"mailto:?subject=Graptolites&#038;body=%20(https:\/\/www.bgs.ac.uk\/discovering-geology\/fossils-and-geological-time\/graptolites\/)\"><span class=\"icon-mail\"><span class=\"hidden\">Email<\/span><\/span><\/a><a href=\"#\" data-copy=\"https:\/\/www.bgs.ac.uk\/discovering-geology\/fossils-and-geological-time\/graptolites\/\" class=\"copy-url-on-click\"><span class=\"icon-link\"><span class=\"hidden\">Copy Link<\/span><\/span><\/a><\/div><\/div>\t\t\t\t\t\t\t<\/section>\n\t\t\t\n\n\n<section class=\"wp-block-bgs-blocks-content-container content-section\"><div class=\"container\"><div class=\"row\"><div class=\"col-12\">\n<p>Fossil graptolites are thin, often shiny, markings on rock surfaces that look like pencil marks, and their name comes from the Greek for &#8216;writing in the rocks&#8217;. They are the remains of intricate colonies, some of which accommodated up to 5000 individual animals; these individuals lived in a skeleton of collagen, similar to the material from which our fingernails are made. We focus on the two main groups: dendroids and planktonic graptolites.<\/p>\n\n\n\n<p>They\nlived between the Cambrian and Carboniferous periods, about 520 to 350 million\nyears ago.<\/p>\n\n\n<figure  class=\"img-wrap\"><a href=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/05\/P549553_1332x690.jpg\" data-toggle=\"lightbox\" data-footer=\"&lt;p&gt;&lt;em&gt;Didymograptus &#8216;bifidus&#8217;&lt;\/em&gt; , from the Ordovician of South Wales, was about 2 cm long. BGS \u00a9 UKRI.&lt;\/p&gt;\n\" data-gallery=\"gallery_9719\"><img decoding=\"async\" src=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/05\/P549553_1332x690-150x150.jpg\" class=\"lazy-blur\" alt=\"Didymograptus &#039;bifidus&#039; from the Ordovician of South Wales. About 2 cm long.\" data-src=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/05\/P549553_1332x690-960x497.jpg\" \/><\/a><figcaption class=\"caption \">\n\t\t\t\t\t<div class=\"caption-icon\">\n\t\t\t\t\t\t<img decoding=\"async\" src=\"https:\/\/www.bgs.ac.uk\/wp-content\/themes\/bgs\/img\/info-caption.svg\" alt=\"Information icon\">\n\t\t\t\t\t<\/div>\n\t\t\t\t\t<div class=\"caption-text\"><p><em>Didymograptus &#8216;bifidus&#8217;<\/em> , from the Ordovician of South Wales, was about 2 cm long. BGS \u00a9 UKRI.<\/p>\n<\/div>\n\t\t\t\t\t<div class=\"expand-box expand-box-top\"><a href=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/05\/P549553_1332x690.jpg\" data-toggle=\"lightbox\" data-footer=\"&lt;p&gt;&lt;em&gt;Didymograptus &#8216;bifidus&#8217;&lt;\/em&gt; , from the Ordovician of South Wales, was about 2 cm long. BGS \u00a9 UKRI.&lt;\/p&gt;\n\" data-gallery=\"gallery_9719\"><img decoding=\"async\" src=\"https:\/\/www.bgs.ac.uk\/wp-content\/themes\/bgs\/img\/expand.svg\" alt=\"Expand icon\"><\/a><\/div>\n\t\t\t\t<\/figcaption><\/figure>\n\n\n<ul><li><a href=\"#animal\">The animal<\/a><\/li><li><a href=\"#environment\">Environment<\/a><\/li><li><a href=\"#geologist\">The geologists\u2019 tool<\/a><\/li><li><a href=\"#fun-fact\">Fun facts<\/a><\/li><li><a href=\"#3d-fossil\">3D fossil models<\/a><\/li><\/ul>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"animal\">The animal<\/h2>\n\n\n\n<p>Graptolites were colonial animals that lived in an interconnected system of tubes. From an initial &#8217;embryonic&#8217;, cone-like tube (the sicula), subsequent tubes (thecae) are arranged in branches (stipes) to make up the whole colony (rhabdosome). Each individual animal is called a zooid.<\/p>\n\n\n\t\t\t\t<div  class=\"owl-carousel carousel-primary-color carousel owl-theme thumbs-carousel-js\">\n\t\t\t\t\t<div class=\"item\"><figure  class=\"img-wrap\"><a href=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/04\/Didymograptus.jpg\" data-toggle=\"lightbox\" data-footer=\"&lt;p&gt;&lt;em&gt;Didymograptus&lt;\/em&gt;, a &#8216;tuning fork&#8217; graptoloid, showing the main parts of the rhabdosome. BGS \u00a9 UKRI.&lt;\/p&gt;\n\" data-gallery=\"gallery_50932\"><img decoding=\"async\" src=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/04\/Didymograptus.jpg\" class=\"attachment-medium size-medium\" alt=\"Didymograptus, a tuning folk graptoloid, showing the main parts of the rhabdosome.\" \/><\/a><figcaption class=\"caption \">\n\t\t\t\t\t<div class=\"caption-icon\">\n\t\t\t\t\t\t<img decoding=\"async\" src=\"https:\/\/www.bgs.ac.uk\/wp-content\/themes\/bgs\/img\/info-caption.svg\" alt=\"Information icon\">\n\t\t\t\t\t<\/div>\n\t\t\t\t\t<div class=\"caption-text\"><p><em>Didymograptus<\/em>, a &#8216;tuning fork&#8217; graptoloid, showing the main parts of the rhabdosome. BGS \u00a9 UKRI.<\/p>\n<\/div>\n\t\t\t\t\t<div class=\"expand-box expand-box-top\"><a href=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/04\/Didymograptus.jpg\" data-toggle=\"lightbox\" data-footer=\"&lt;p&gt;&lt;em&gt;Didymograptus&lt;\/em&gt;, a &#8216;tuning fork&#8217; graptoloid, showing the main parts of the rhabdosome. BGS \u00a9 UKRI.&lt;\/p&gt;\n\" data-gallery=\"gallery_50932\"><img decoding=\"async\" src=\"https:\/\/www.bgs.ac.uk\/wp-content\/themes\/bgs\/img\/expand.svg\" alt=\"Expand icon\"><\/a><\/div>\n\t\t\t\t<\/figcaption><\/figure><\/div><div class=\"item\"><figure  class=\"img-wrap\"><a href=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/04\/Climacograptus.jpg\" data-toggle=\"lightbox\" data-footer=\"&lt;p&gt;A close-up of the thecae of &lt;em&gt;Climacograptus&lt;\/em&gt; partly cut away to show the internal structure of the interconnecting tubes and one of the zooids. The thread-like, central nema (or virgula), which may protrude some distance beyond the stipes, may have been used for attachment when juvenile, for strengthening or to attach a floatation device or vane. BGS \u00a9 UKRI.&lt;\/p&gt;\n\" data-gallery=\"gallery_50932\"><img decoding=\"async\" src=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/04\/Climacograptus.jpg\" class=\"attachment-medium size-medium\" alt=\"A close-up of the thecae of Climacograptus partly cut away to show the internal structure of the interconnecting tubes and one of the zooids. The thread-like, central nema (or virgula), which may protrude some distance beyond the stipes, may have been used for attachment when juvenile, for strengthening or to attach a floatation device or vane.\" \/><\/a><figcaption class=\"caption \">\n\t\t\t\t\t<div class=\"caption-icon\">\n\t\t\t\t\t\t<img decoding=\"async\" src=\"https:\/\/www.bgs.ac.uk\/wp-content\/themes\/bgs\/img\/info-caption.svg\" alt=\"Information icon\">\n\t\t\t\t\t<\/div>\n\t\t\t\t\t<div class=\"caption-text\"><p>A close-up of the thecae of <em>Climacograptus<\/em> partly cut away to show the internal structure of the interconnecting tubes and one of the zooids. The thread-like, central nema (or virgula), which may protrude some distance beyond the stipes, may have been used for attachment when juvenile, for strengthening or to attach a floatation device or vane. BGS \u00a9 UKRI.<\/p>\n<\/div>\n\t\t\t\t\t<div class=\"expand-box expand-box-top\"><a href=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/04\/Climacograptus.jpg\" data-toggle=\"lightbox\" data-footer=\"&lt;p&gt;A close-up of the thecae of &lt;em&gt;Climacograptus&lt;\/em&gt; partly cut away to show the internal structure of the interconnecting tubes and one of the zooids. The thread-like, central nema (or virgula), which may protrude some distance beyond the stipes, may have been used for attachment when juvenile, for strengthening or to attach a floatation device or vane. BGS \u00a9 UKRI.&lt;\/p&gt;\n\" data-gallery=\"gallery_50932\"><img decoding=\"async\" src=\"https:\/\/www.bgs.ac.uk\/wp-content\/themes\/bgs\/img\/expand.svg\" alt=\"Expand icon\"><\/a><\/div>\n\t\t\t\t<\/figcaption><\/figure><\/div>\t\t\t\t<\/div>\n\t\t\t\t\n\n\n<h2 class=\"wp-block-heading\" id=\"environment\">Environment <\/h2>\n\n\n\n<p>The earliest graptolites lived on the sea bed, attached to boulders or forming upright cones rooted into soft mud. This is still the lifestyle of the living relatives of graptolites. <\/p>\n\n\n<figure  class=\"img-wrap\"><a href=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/04\/Earliest_graptolites_lived_on_the_sea_bed.jpg\" data-toggle=\"lightbox\" data-footer=\"&lt;p&gt;The earliest graptolites lived on the sea bed (a and b) while later forms were free floating (c\u2013l). BGS \u00a9 UKRI.&lt;\/p&gt;\n\" data-gallery=\"gallery_35816\"><img decoding=\"async\" src=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/04\/Earliest_graptolites_lived_on_the_sea_bed-150x150.jpg\" class=\"lazy-blur\" alt=\"The earliest graptolites lived on the sea bed, see below for full description.\" data-src=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/04\/Earliest_graptolites_lived_on_the_sea_bed.jpg\" \/><\/a><figcaption class=\"caption \">\n\t\t\t\t\t<div class=\"caption-icon\">\n\t\t\t\t\t\t<img decoding=\"async\" src=\"https:\/\/www.bgs.ac.uk\/wp-content\/themes\/bgs\/img\/info-caption.svg\" alt=\"Information icon\">\n\t\t\t\t\t<\/div>\n\t\t\t\t\t<div class=\"caption-text\"><p>The earliest graptolites lived on the sea bed (a and b) while later forms were free floating (c\u2013l). BGS \u00a9 UKRI.<\/p>\n<\/div>\n\t\t\t\t\t<div class=\"expand-box expand-box-top\"><a href=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/04\/Earliest_graptolites_lived_on_the_sea_bed.jpg\" data-toggle=\"lightbox\" data-footer=\"&lt;p&gt;The earliest graptolites lived on the sea bed (a and b) while later forms were free floating (c\u2013l). BGS \u00a9 UKRI.&lt;\/p&gt;\n\" data-gallery=\"gallery_35816\"><img decoding=\"async\" src=\"https:\/\/www.bgs.ac.uk\/wp-content\/themes\/bgs\/img\/expand.svg\" alt=\"Expand icon\"><\/a><\/div>\n\t\t\t\t<\/figcaption><\/figure>\n\n\n<p>At the beginning of the Ordovician period graptolites became free floating. They were amongst the first animals to colonise the open sea and were able to exploit enormous untapped reserves of food (single-celled organisms) in the upper layers of the oceans. Different species evolved rapidly in order to exploit these food reserves and in response to the new challenge of a floating life.<\/p>\n\n\n\n<p>Graptolites were common where food was abundant, especially in upwelling currents, where deep water, with its load of nutrients, is forced upwards and into shallower waters in areas such as the tropics and at the edge of the continental shelf. Some were deep-water specialists, whilst others were opportunists seeking out temporary supplies of food. Some colonies evolved into enormous harvesting arrays, capable of living to a significant age, perhaps up to 20 years. Others evolved into slim, short colonies or into gently curved forms, which rotated through the water as they fed. Using the distribution of fossil graptolites, we can begin to reconstruct the oceans in which they lived.<\/p>\n\n\n\n<p>A floating life is a challenge; graptolites responded to this by evolving a range of hydrodynamic strategies. Long nemas evolved to retard sinking and hooked, spiny and net-like forms appeared, which would have had a high drag so that they moved slowly. The zooids may have helped the colony to move and possibly secreted gas or low-density fat to help the colony to rise through the water.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Modern relatives <\/h3>\n\n\n\n<p>Although graptolites are now extinct, living marine animals called pterobranchs appear to be closely related. Pterobranchs do not grow their tube-like skeleton in the same, passive way as we grow our bones or an oyster makes its shell. Rather, the pterobranch zooids actively construct them, much as a spider weaves its web or termites build their nest. Graptolites probably did the same: the criss-crossing bandages in the outer layer of a theca, which look rather like the bandages wrapping an Egyptian mummy, were apparently &#8216;trowelled&#8217; on by a secretory organ akin to that of pterobranchs.<\/p>\n\n\n<figure  class=\"img-wrap\"><img decoding=\"async\" src=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/04\/Cephalodiscus_gracilis-150x150.jpg\" class=\"lazy-blur\" alt=\"Cephalodiscus gracilis, a living pterobranch thought to be related to graptolites. Two zooids have extended their feathery filtering nets to feed.\" data-src=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/04\/Cephalodiscus_gracilis.jpg\" \/><figcaption class=\"caption \">\n\t\t\t\t\t<div class=\"caption-icon\">\n\t\t\t\t\t\t<img decoding=\"async\" src=\"https:\/\/www.bgs.ac.uk\/wp-content\/themes\/bgs\/img\/info-caption.svg\" alt=\"Information icon\">\n\t\t\t\t\t<\/div>\n\t\t\t\t\t<div class=\"caption-text\"><p><em>Cephalodiscus gracilis<\/em>, a living pterobranch thought to be related to graptolites. Two zooids have extended their feathery filtering nets to feed. BGS \u00a9 UKRI.<\/p>\n<\/div>\n\t\t\t\t\t\n\t\t\t\t<\/figcaption><\/figure>\n\n\n<h2 class=\"wp-block-heading\" id=\"geologist\">The geologists\u2019 tool<\/h2>\n\n\n\n<p>Graptolites are excellent geological time-keepers; they can be used to date the rocks in which they are found. They evolved quickly and assumed a wealth of easily recognisable shapes. Many of these evolutionary steps, which can be traced around much of the world, define periods of time. Some of these time-slices are only a few hundred thousand years long, which, to a geologist, amounts to pinpoint accuracy given that all this took place hundreds of millions of years ago!<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Dendroids<\/h3>\n\n\n\t\t\t\t<div  class=\"owl-carousel carousel-primary-color carousel owl-theme thumbs-carousel-js\">\n\t\t\t\t\t<div class=\"item\"><figure  class=\"img-wrap\"><img decoding=\"async\" src=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/04\/Dictyonema.jpg\" class=\"attachment-medium size-medium\" alt=\"Dictyonema (from the Silurian) had many branches and thousands of zooids in its cone-shaped colony\" \/><figcaption class=\"caption \">\n\t\t\t\t\t<div class=\"caption-icon\">\n\t\t\t\t\t\t<img decoding=\"async\" src=\"https:\/\/www.bgs.ac.uk\/wp-content\/themes\/bgs\/img\/info-caption.svg\" alt=\"Information icon\">\n\t\t\t\t\t<\/div>\n\t\t\t\t\t<div class=\"caption-text\"><p><em>Dictyonema<\/em> (from the Silurian Period) had many branches and thousands of zooids in its cone-shaped colony. \u00a9 The British and Irish Graptolite Group (BIG G).<\/p>\n<\/div>\n\t\t\t\t\t\n\t\t\t\t<\/figcaption><\/figure><\/div><div class=\"item\"><figure  class=\"img-wrap\"><img decoding=\"async\" src=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/04\/Anisograptids.jpg\" class=\"attachment-medium size-medium\" alt=\"Anisograptids such as Ordovician Clonograptus are transitional between dendroids and graptoloids. Most of these &#039;planktonc dendroids&#039; had two types of theca, but fewer stipes. Dendroids first evolved in the Cambrian and lived rooted to the sea bed. Dendroids had two types of thecae, possibly for males and females.\" \/><figcaption class=\"caption \">\n\t\t\t\t\t<div class=\"caption-icon\">\n\t\t\t\t\t\t<img decoding=\"async\" src=\"https:\/\/www.bgs.ac.uk\/wp-content\/themes\/bgs\/img\/info-caption.svg\" alt=\"Information icon\">\n\t\t\t\t\t<\/div>\n\t\t\t\t\t<div class=\"caption-text\"><p>Anisograptids such as the Ordovician <em>Clonograptus<\/em> are transitional between dendroids and graptoloids. Most of these &#8216;planktonc dendroids&#8217; had two types of theca, but fewer stipes. Dendroids first evolved in the Cambrian and lived rooted to the sea bed. Dendroids had two types of thecae, possibly for males and females. \u00a9 The British and Irish Graptolite Group (BIG G).<\/p>\n<\/div>\n\t\t\t\t\t\n\t\t\t\t<\/figcaption><\/figure><\/div>\t\t\t\t<\/div>\n\t\t\t\t\n\n\n<h3 class=\"wp-block-heading\">Graptoloids<\/h3>\n\n\n<figure  class=\"img-wrap\"><a href=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/05\/Graptoloids_1332x690.jpg\" data-toggle=\"lightbox\" data-footer=\"&lt;p&gt;Graptoloids were all planktonic, had only one kind of theca and may have been hermaphrodites. Dichograptids flourished in the early Ordovician. Their stipes were few and arranged in various ways: e.g. stretched out sideways (horizontal), hanging down (pendant) or turned upwards (reclined). &lt;em&gt;Tetragraptus&lt;\/em&gt; had four horizontal or pendant stipes (a). &lt;em&gt;Didymograptus&lt;\/em&gt; had two pendant stipes (b). &lt;em&gt;Isograptus&lt;\/em&gt; had reclined stipes (and a long nema extending above the sicula) (c).\u00a0\u00a9 The British and Irish Graptolite Group (BIG G).&lt;\/p&gt;\n\" data-gallery=\"gallery_95587\"><img decoding=\"async\" src=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/05\/Graptoloids_1332x690-150x150.jpg\" class=\"lazy-blur\" alt=\"Graptoloids were all planktonic, had only one kind of theca and may have been hermaphrodites. Dichograptids flourished in the early Ordovician. Their stipes were few and arranged in various ways: e.g. stretched out sideways (horizontal), hanging down (pendant) or turned upwards (reclined). Tetragraptus had four horizontal or pendant stipes (a). Didymograptus had two pendant stipes (b). Isograptus had reclined stipes (and a long nema extending above the sicula) (c).\" data-src=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/05\/Graptoloids_1332x690-960x497.jpg\" \/><\/a><figcaption class=\"caption \">\n\t\t\t\t\t<div class=\"caption-icon\">\n\t\t\t\t\t\t<img decoding=\"async\" src=\"https:\/\/www.bgs.ac.uk\/wp-content\/themes\/bgs\/img\/info-caption.svg\" alt=\"Information icon\">\n\t\t\t\t\t<\/div>\n\t\t\t\t\t<div class=\"caption-text\"><p>Graptoloids were all planktonic, had only one kind of theca and may have been hermaphrodites. Dichograptids flourished in the early Ordovician. Their stipes were few and arranged in various ways: e.g. stretched out sideways (horizontal), hanging down (pendant) or turned upwards (reclined). <em>Tetragraptus<\/em> had four horizontal or pendant stipes (a). <em>Didymograptus<\/em> had two pendant stipes (b). <em>Isograptus<\/em> had reclined stipes (and a long nema extending above the sicula) (c).\u00a0\u00a9 The British and Irish Graptolite Group (BIG G).<\/p>\n<\/div>\n\t\t\t\t\t<div class=\"expand-box expand-box-top\"><a href=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/05\/Graptoloids_1332x690.jpg\" data-toggle=\"lightbox\" data-footer=\"&lt;p&gt;Graptoloids were all planktonic, had only one kind of theca and may have been hermaphrodites. Dichograptids flourished in the early Ordovician. Their stipes were few and arranged in various ways: e.g. stretched out sideways (horizontal), hanging down (pendant) or turned upwards (reclined). &lt;em&gt;Tetragraptus&lt;\/em&gt; had four horizontal or pendant stipes (a). &lt;em&gt;Didymograptus&lt;\/em&gt; had two pendant stipes (b). &lt;em&gt;Isograptus&lt;\/em&gt; had reclined stipes (and a long nema extending above the sicula) (c).\u00a0\u00a9 The British and Irish Graptolite Group (BIG G).&lt;\/p&gt;\n\" data-gallery=\"gallery_95587\"><img decoding=\"async\" src=\"https:\/\/www.bgs.ac.uk\/wp-content\/themes\/bgs\/img\/expand.svg\" alt=\"Expand icon\"><\/a><\/div>\n\t\t\t\t<\/figcaption><\/figure>\n\n\n<h3 class=\"wp-block-heading\">Diplograptids<\/h3>\n\n\n<figure  class=\"img-wrap\"><a href=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/05\/Diplograptids_1332x690.jpg\" data-toggle=\"lightbox\" data-footer=\"&lt;p&gt;Diplograptids evolved from dichograptids in the Ordovician. &lt;em&gt;Orthograptus&lt;\/em&gt;\u00a0and\u00a0&lt;em&gt;Dicranograptus&lt;\/em&gt;\u00a0are from the Ordovician of southern Scotland.&lt;\/p&gt;\n&lt;p&gt;a) The stipes of &lt;em&gt;Orthograptus &lt;\/em&gt;were fused \u2018back-to-back\u2019 (i.e. scandent).&lt;\/p&gt;\n&lt;p&gt;b) Some later types of diplograptids became partly \u2018unzipped\u2019, like the Y-shaped &lt;em&gt;Dicranograptus&lt;\/em&gt; (the biserial part is 5\u00a0mm long).&lt;\/p&gt;\n&lt;p&gt;c) &lt;em&gt;Spirograptus turriculatus &lt;\/em&gt;was coiled or spring-like&lt;\/p&gt;\n&lt;p&gt;d) &lt;em&gt;Rastrites &lt;\/em&gt;had a curved stipe with long thecae up to 3\u00a0mm long&lt;\/p&gt;\n&lt;p&gt;\u00a9 The British and Irish Graptolite Group (BIG G).&lt;\/p&gt;\n\" data-gallery=\"gallery_15626\"><img decoding=\"async\" src=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/05\/Diplograptids_1332x690-150x150.jpg\" class=\"lazy-blur\" alt=\"a) The stipes of Orthograptuswere fused \u2018back-to-back\u2019 (i.e. scandent). b) Some later types of diplograptids became partly \u2018unzipped\u2019, like the Y-shaped Dicranograptus (the biserial part is 5mm long). c) Spirograptus turriculatuswas coiled or spring-like d) Rastriteshad a curved stipe with long thecae up to 3mm long\" data-src=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/05\/Diplograptids_1332x690-960x497.jpg\" \/><\/a><figcaption class=\"caption \">\n\t\t\t\t\t<div class=\"caption-icon\">\n\t\t\t\t\t\t<img decoding=\"async\" src=\"https:\/\/www.bgs.ac.uk\/wp-content\/themes\/bgs\/img\/info-caption.svg\" alt=\"Information icon\">\n\t\t\t\t\t<\/div>\n\t\t\t\t\t<div class=\"caption-text\"><p>Diplograptids evolved from dichograptids in the Ordovician. <em>Orthograptus<\/em>\u00a0and\u00a0<em>Dicranograptus<\/em>\u00a0are from the Ordovician of southern Scotland.<\/p>\n<p>a) The stipes of <em>Orthograptus <\/em>were fused \u2018back-to-back\u2019 (i.e. scandent).<\/p>\n<p>b) Some later types of diplograptids became partly \u2018unzipped\u2019, like the Y-shaped <em>Dicranograptus<\/em> (the biserial part is 5\u00a0mm long).<\/p>\n<p>c) <em>Spirograptus turriculatus <\/em>was coiled or spring-like<\/p>\n<p>d) <em>Rastrites <\/em>had a curved stipe with long thecae up to 3\u00a0mm long<\/p>\n<p>\u00a9 The British and Irish Graptolite Group (BIG G).<\/p>\n<\/div>\n\t\t\t\t\t<div class=\"expand-box expand-box-top\"><a href=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/05\/Diplograptids_1332x690.jpg\" data-toggle=\"lightbox\" data-footer=\"&lt;p&gt;Diplograptids evolved from dichograptids in the Ordovician. &lt;em&gt;Orthograptus&lt;\/em&gt;\u00a0and\u00a0&lt;em&gt;Dicranograptus&lt;\/em&gt;\u00a0are from the Ordovician of southern Scotland.&lt;\/p&gt;\n&lt;p&gt;a) The stipes of &lt;em&gt;Orthograptus &lt;\/em&gt;were fused \u2018back-to-back\u2019 (i.e. scandent).&lt;\/p&gt;\n&lt;p&gt;b) Some later types of diplograptids became partly \u2018unzipped\u2019, like the Y-shaped &lt;em&gt;Dicranograptus&lt;\/em&gt; (the biserial part is 5\u00a0mm long).&lt;\/p&gt;\n&lt;p&gt;c) &lt;em&gt;Spirograptus turriculatus &lt;\/em&gt;was coiled or spring-like&lt;\/p&gt;\n&lt;p&gt;d) &lt;em&gt;Rastrites &lt;\/em&gt;had a curved stipe with long thecae up to 3\u00a0mm long&lt;\/p&gt;\n&lt;p&gt;\u00a9 The British and Irish Graptolite Group (BIG G).&lt;\/p&gt;\n\" data-gallery=\"gallery_15626\"><img decoding=\"async\" src=\"https:\/\/www.bgs.ac.uk\/wp-content\/themes\/bgs\/img\/expand.svg\" alt=\"Expand icon\"><\/a><\/div>\n\t\t\t\t<\/figcaption><\/figure>\n\n\n<h3 class=\"wp-block-heading\">Monograptids<\/h3>\n\n\n\n<p>One-stiped monograptids appeared at the beginning of the Silurian and evolved rapidly into many coiled, curved and straight species, with elongate, hooked or lobed thecae. <em>Spirograptus turriculatus<\/em>, <em>Rastrites<\/em> and <em>Monograptus lobiferus<\/em> are from the Silurian (Llandovery).<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Graptolites&nbsp;through time <\/h3>\n\n\n<figure  class=\"img-wrap\"><a href=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/04\/The_history_of_graptolites.jpg\" data-toggle=\"lightbox\" data-footer=\"&lt;p&gt;The history of graptolites (dendroids and graptoloids) and their diversity related to global events. The geological position of illustrated specimens are shown in italics. BGS \u00a9 UKRI.&lt;\/p&gt;\n\" data-gallery=\"gallery_54669\"><img decoding=\"async\" src=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/04\/The_history_of_graptolites-150x150.jpg\" class=\"lazy-blur\" alt=\"The history of graptolites (dendroids and graptoloids) and their diversity related to global events. The geological position of illustrated specimens are shown in italics.\" data-src=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/04\/The_history_of_graptolites.jpg\" \/><\/a><figcaption class=\"caption \">\n\t\t\t\t\t<div class=\"caption-icon\">\n\t\t\t\t\t\t<img decoding=\"async\" src=\"https:\/\/www.bgs.ac.uk\/wp-content\/themes\/bgs\/img\/info-caption.svg\" alt=\"Information icon\">\n\t\t\t\t\t<\/div>\n\t\t\t\t\t<div class=\"caption-text\"><p>The history of graptolites (dendroids and graptoloids) and their diversity related to global events. The geological position of illustrated specimens are shown in italics. BGS \u00a9 UKRI.<\/p>\n<\/div>\n\t\t\t\t\t<div class=\"expand-box expand-box-top\"><a href=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/04\/The_history_of_graptolites.jpg\" data-toggle=\"lightbox\" data-footer=\"&lt;p&gt;The history of graptolites (dendroids and graptoloids) and their diversity related to global events. The geological position of illustrated specimens are shown in italics. BGS \u00a9 UKRI.&lt;\/p&gt;\n\" data-gallery=\"gallery_54669\"><img decoding=\"async\" src=\"https:\/\/www.bgs.ac.uk\/wp-content\/themes\/bgs\/img\/expand.svg\" alt=\"Expand icon\"><\/a><\/div>\n\t\t\t\t<\/figcaption><\/figure>\n\n\n<h3 class=\"wp-block-heading\">Graptolites&nbsp;in Britain<\/h3>\n\n\n\n<p>Graptolites are found only in Palaeozoic rocks such as those in Scotland, Wales and north-western England. The oldest dendroids occur in middle Cambrian rocks, but they can be found in rocks as young as the Carboniferous. Planktonic graptolites are particularly common in Ordovician and Silurian shales and mudstones.<\/p>\n\n\n<figure  class=\"img-wrap\"><a href=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/04\/Palaeozoic_rocks_of_the_UK.jpg\" data-toggle=\"lightbox\" data-footer=\"&lt;p&gt;Palaeozoic rocks of the UK and some good places to look for graptolites (see black spots). The colour code for geological periods is the same as for the history diagram. BGS \u00a9 UKRI.&lt;\/p&gt;\n\" data-gallery=\"gallery_41204\"><img decoding=\"async\" src=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/04\/Palaeozoic_rocks_of_the_UK-150x150.jpg\" class=\"lazy-blur\" alt=\"Palaeozoic rocks of the UK and some good places to look for graptolites (see black spots). The colour code for geological periods is the same as for the history diagram.\" data-src=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/04\/Palaeozoic_rocks_of_the_UK.jpg\" \/><\/a><figcaption class=\"caption \">\n\t\t\t\t\t<div class=\"caption-icon\">\n\t\t\t\t\t\t<img decoding=\"async\" src=\"https:\/\/www.bgs.ac.uk\/wp-content\/themes\/bgs\/img\/info-caption.svg\" alt=\"Information icon\">\n\t\t\t\t\t<\/div>\n\t\t\t\t\t<div class=\"caption-text\"><p>Palaeozoic rocks of the UK and some good places to look for graptolites (see black spots). The colour code for geological periods is the same as for the history diagram. BGS \u00a9 UKRI.<\/p>\n<\/div>\n\t\t\t\t\t<div class=\"expand-box expand-box-top\"><a href=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/04\/Palaeozoic_rocks_of_the_UK.jpg\" data-toggle=\"lightbox\" data-footer=\"&lt;p&gt;Palaeozoic rocks of the UK and some good places to look for graptolites (see black spots). The colour code for geological periods is the same as for the history diagram. BGS \u00a9 UKRI.&lt;\/p&gt;\n\" data-gallery=\"gallery_41204\"><img decoding=\"async\" src=\"https:\/\/www.bgs.ac.uk\/wp-content\/themes\/bgs\/img\/expand.svg\" alt=\"Expand icon\"><\/a><\/div>\n\t\t\t\t<\/figcaption><\/figure>\n\n\n<h2 class=\"wp-block-heading\" id=\"fun-fact\">Fun facts<\/h2>\n\n\n\n<p>Graptolites are thought to have been hermaphroditic,\u00a0with both male and female sexual organs on one single zooid. To avoid self-fertilisation, or inbreeding, zooids could have had the potential to be temporarily male, female or neuter. Zooids maturing at the near end of a colony might initially have been males whilst those occupying the larger, distal thecae may have manifested the female phase. But nobody knows for sure!<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"3d-fossil\">3D fossil models<\/h2>\n\n\n<figure  class=\"img-wrap\"><a href=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/05\/P867340_1332x690.jpg\" data-toggle=\"lightbox\" data-footer=\"&lt;p&gt;&lt;em&gt;Orthograptus truncatus &lt;\/em&gt;var.&lt;em&gt; corrisensis&lt;\/em&gt; Davies. (Ordovician, Ashgill.) See 3D fossils online. GB3D Type Fossils. BGS \u00a9 UKRI.&lt;\/p&gt;\n\" data-gallery=\"gallery_47641\"><img decoding=\"async\" src=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/05\/P867340_1332x690-150x150.jpg\" class=\"lazy-blur\" alt=\"Orthograptus truncatus var. corrisensis. (SM A 10007 \u2013 Holotype). Ashgill Series (Ordovician Period) (443.8 \u2013 449 Ma B.P.) [Closest ICS interval: Late Ordovician Epoch]. See 3D fossils online. GB3D Type Fossils.\" data-src=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/05\/P867340_1332x690-960x497.jpg\" \/><\/a><figcaption class=\"caption \">\n\t\t\t\t\t<div class=\"caption-icon\">\n\t\t\t\t\t\t<img decoding=\"async\" src=\"https:\/\/www.bgs.ac.uk\/wp-content\/themes\/bgs\/img\/info-caption.svg\" alt=\"Information icon\">\n\t\t\t\t\t<\/div>\n\t\t\t\t\t<div class=\"caption-text\"><p><em>Orthograptus truncatus <\/em>var.<em> corrisensis<\/em> Davies. (Ordovician, Ashgill.) See 3D fossils online. GB3D Type Fossils. BGS \u00a9 UKRI.<\/p>\n<\/div>\n\t\t\t\t\t<div class=\"expand-box expand-box-top\"><a href=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/05\/P867340_1332x690.jpg\" data-toggle=\"lightbox\" data-footer=\"&lt;p&gt;&lt;em&gt;Orthograptus truncatus &lt;\/em&gt;var.&lt;em&gt; corrisensis&lt;\/em&gt; Davies. (Ordovician, Ashgill.) See 3D fossils online. GB3D Type Fossils. BGS \u00a9 UKRI.&lt;\/p&gt;\n\" data-gallery=\"gallery_47641\"><img decoding=\"async\" src=\"https:\/\/www.bgs.ac.uk\/wp-content\/themes\/bgs\/img\/expand.svg\" alt=\"Expand icon\"><\/a><\/div>\n\t\t\t\t<\/figcaption><\/figure>\n\n\n<p>Many of the fossils in the&nbsp;<a href=\"https:\/\/www.bgs.ac.uk\/geological-data\/national-geological-repository\/palaeontology-collections\/\">BGS palaeontology collections<\/a>&nbsp;are available to view and download as 3D models. To view this fossil, or others like it, in 3D visit <a rel=\"noreferrer noopener\" href=\"http:\/\/www.3d-fossils.ac.uk\/home.html\" target=\"_blank\">GB3D Type Fossils<\/a>.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Reference<\/h2>\n\n\n\n<p>Wilkinson, I P, Rigby, S, and Zalasiewicz, J A. 2001. Graptolites: fossil focus. (Nottingham, UK: <em>British Geological Survey<\/em>.)<\/p>\n<\/div><\/div><\/div><\/section>\n\n\n\n\n\t\t\t\t\t<section   id=\"latest-content-2495-block_5ed5145d20854\" class=\"grid-section  primary-background   \" >\n\t\t\t\t\t\t<div class=\"container\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t<div class=\"row header-of-section\">\n\t\t\t\t\t\t\t\t<div class=\"col-12\">\n\t\t\t\t\t\t\t\t\t<h2>You may also be interested in<\/h2>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t<div class=\"row grid-wrap\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t<div class=\"col-lg-6 col-12\">\n\t<div class=\"cards cards-orizontal-sm  cards-find-more  cards-bordered\">\n\t\t\t\t<a href=\"https:\/\/www.bgs.ac.uk\/discovering-geology\/\" class=\"media-wrap\">\n\t\t\t<img decoding=\"async\" src=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/04\/feature_homepage_p815563-150x150.jpg\" class=\"lazy-blur wp-post-image\" alt=\"Ammonite p815563\" data-src=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/04\/feature_homepage_p815563.jpg\" \/>\t\t\t\t\t<\/a>\n\t\t\t\t<div class=\"info-wrap\">\n\t\t\t<div class=\"info\">\n\t\t\t\t<h4><a href=\"https:\/\/www.bgs.ac.uk\/discovering-geology\/\">Discovering Geology<\/a><\/h4>\n\t\t\t\t\t\t\t\t\t\t\t\t\t<p>Discovering Geology introduces a range of geoscience topics to school-age students and learners of all ages.<\/p>\n\t\t\t\t\t\t\t<\/div>\n\t\t\t<a href=\"https:\/\/www.bgs.ac.uk\/discovering-geology\/\">Show more<\/a>\n\t\t<\/div>\n\t<\/div>\n<\/div>\n<div class=\"col-lg-6 col-12\">\n\t<div class=\"cards cards-orizontal-sm  cards-find-more  cards-bordered\">\n\t\t\t\t<a href=\"https:\/\/www.bgs.ac.uk\/discovering-geology\/fossils-and-geological-time\/\" class=\"media-wrap\">\n\t\t\t<img decoding=\"async\" src=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2021\/06\/fishThroughTime-150x150.jpg\" class=\"lazy-blur wp-post-image\" alt=\"fishThroughTime\" data-src=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2021\/06\/fishThroughTime.jpg\" \/>\t\t\t\t\t<\/a>\n\t\t\t\t<div class=\"info-wrap\">\n\t\t\t<div class=\"info\">\n\t\t\t\t<h4><a href=\"https:\/\/www.bgs.ac.uk\/discovering-geology\/fossils-and-geological-time\/\">Fossils and geological time<\/a><\/h4>\n\t\t\t\t\t\t\t\t\t\t\t\t\t<p>Take a look at the history of the Earth, from its formation over four and a half billion years ago to present times.<\/p>\n\t\t\t\t\t\t\t<\/div>\n\t\t\t<a href=\"https:\/\/www.bgs.ac.uk\/discovering-geology\/fossils-and-geological-time\/\">Show more<\/a>\n\t\t<\/div>\n\t<\/div>\n<\/div>\n<div class=\"col-lg-6 col-12\">\n\t<div class=\"cards cards-orizontal-sm  cards-find-more  cards-bordered\">\n\t\t\t\t<a href=\"https:\/\/www.bgs.ac.uk\/discovering-geology\/fossils-and-geological-time\/fossils\/\" class=\"media-wrap\">\n\t\t\t<img decoding=\"async\" src=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2021\/08\/P550300-150x150.jpg\" class=\"lazy-blur wp-post-image\" alt=\"P550300\" data-src=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2021\/08\/P550300.jpg\" \/>\t\t\t\t\t<\/a>\n\t\t\t\t<div class=\"info-wrap\">\n\t\t\t<div class=\"info\">\n\t\t\t\t<h4><a href=\"https:\/\/www.bgs.ac.uk\/discovering-geology\/fossils-and-geological-time\/fossils\/\">Fossils<\/a><\/h4>\n\t\t\t\t\t\t\t\t\t\t\t\t\t<p>What is a fossil and why do we study them? Explore the different methods of fossil preservation.<\/p>\n\t\t\t\t\t\t\t<\/div>\n\t\t\t<a href=\"https:\/\/www.bgs.ac.uk\/discovering-geology\/fossils-and-geological-time\/fossils\/\">Show more<\/a>\n\t\t<\/div>\n\t<\/div>\n<\/div>\n\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t<div class=\"row\">\n\t\t\t\t\t\t\t\t<div class=\"col-12\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t<\/section>\n\t\t\t\t","protected":false},"excerpt":{"rendered":"","protected":false},"author":6,"featured_media":36470,"parent":16685,"menu_order":29,"comment_status":"closed","ping_status":"closed","template":"","meta":{"_acf_changed":false,"_relevanssi_hide_post":"","_relevanssi_hide_content":"","_relevanssi_pin_for_all":"","_relevanssi_pin_keywords":"","_relevanssi_unpin_keywords":"","_relevanssi_related_keywords":"","_relevanssi_related_include_ids":"","_relevanssi_related_exclude_ids":"","_relevanssi_related_no_append":"","_relevanssi_related_not_related":"","_relevanssi_related_posts":"9189,51118,17220,10140,9742,8391","_relevanssi_noindex_reason":"","footnotes":""},"tags":[],"acf":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v22.5 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>Graptolites - British Geological Survey<\/title>\n<meta name=\"description\" content=\"Fossil graptolites are thin, often shiny, markings on rock surfaces that look like pencil marks. 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