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Fossils. Mr. Litaker. How are fossils created. There are five major ways in which a fossil can be preserved. They are: Petrification molds impressions amber and sedimentary fossils . Petrification.
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Fossils Mr. Litaker
How are fossils created • There are five major ways in which a fossil can be preserved. • They are: • Petrification • molds • impressions • amber and • sedimentary fossils
Petrification Petrification occurs when a living object is slowly turned to stone of a huge number of years. Petrification is sometimes called "permineralization" because it is brought about mainly by minerals. Minerals seep through the organic matter in an object, filling it completely. Then the organic matter rots away, but a mineral version of the fossil is left. This process usually works best in the fossilization of trees.
Some of the most famous petrified trees are in California, and contain huge rings that describe ancient eras.
Molds Molds are literally molds of an animal. Sometimes animals became trapped in mud, dirt or clay. Then their bodies deteriorated, leaving behind their shape and size in the ground. When the hole created by this is discovered, it is known as amold.
A mold can be created in two ways. • An organism can deteriorate and leave a hole showing details of its body. • Or a hollow object, such as a shell, can become filled with matter. When the object deteriorates, the matter filling it is left behind as a mold.
Impressions or Carbon Impressions Have you ever seen a dinosaur's footprint? These are formed when mud, clay or silt containing an imprint made by an animal turns to stone. This is an example of an impression, or the impression that an animal leaves in soft matter. These fossils are useful in determining weight and structure of ancient animals. Sometimes, even toenails and pores can be seen!
Amber Some fossils are preserved in amber. Amber is a sap-like substance from trees. It is sap that has dried over hundreds of years. Because tree sap is so sticky, it is possible for bugs and even small animals to be trapped within it.
In time, the sap hardens to amber and a perfect specimen of the creature is preserved. Amber fossils are plentiful, and are sometimes worn as necklaces and bracelets today!
Sedimentary Fossils The sea bedcontains perhaps the most fossils on the earth. This is because the soft ground under the sea is made of sedimentary rock, or rock that is composed of layers of land. When sea creatures die, they drift to the bottom of the ocean and are covered with a layer of sand. In time, a volcano or mudslide, etc.,may cover the surface under which they are buried. In this way, a new layer is added, and the fossil is preserved in layers of time. Therefore, fossils made in this way are sometimes referred to as "sedimentary fossils."
While there are many of these fossils, they are often very hard to get to. Often, they are dug from ground that was once underwater. In fact, fossils in sedimentary layers are useful in indicating when land was above and below ground.
The Precambrian The Precambrian About 4600 million or 4.6 Billion to 545 million years ago. The first evidence of life on Earth is from about 3500 million years ago. During the Precambrian, life was confined to the sea and consisted of simple, single-celled organisms such as bacteria, algae, and soft-bodied animals like jellyfish and worms.
Stromatolites -are fossils which show the life processes of cyanobacteria (formerly called blue-green algae). The primitive cells (Prokaryotic type), lived in huge masses that could form floating mats or extensive reefs. Masses of cyanobacteria on the sea floor deposited calcium carbonate in layers or domes. These layered deposits, which have a distinctive "signiture" are called laminar stromatolites.
Fossilized stromatolites are said to be the oldest known fossils. An untitled article from the Internet suggests that these colonial structures date "back more than 3 billion (American) years" (3,000 million years)
Precambrian Life There really just wasn’t any life forms!
Paleozoic era - occurring between 570 to 240 million years ago. It is subdivided into six periods, the Cambrian, Ordovician, Silurian, Devonian, Carboniferous, and Permian (see each listed individually). During the hiatus between the late Precambrian and Paleozoic eras most of the evidence of the earth's early history was destroyed by erosion.
This famous Burgess Shale picture displays the new creatures that were formed during the Cambrian period. Cambrian Period The Cambrian Period marks an important point in the history of life on earth; it is the time when most of the major groups of animals first appear in the fossil record. This event is sometimes called the "Cambrian Explosion", because of the relatively short time over which this diversity of forms appears.
Cambrian Period * About 545 to 490 million years ago. The first fossils of animals with shells or hard parts occur in rocks of Cambrian age. Life in the Cambrian was confined to the sea and included the first representatives of many invertebrate animals. The first vertebrate animals are known from late in this period. The Cambrian is sometimes called the 'Age of Trilobites', as these were one of the most dominant life forms.
This is A Cambrian trilobite from Utah
Ordovician Period About 490 to 434 mya. Life was confined to the sea. The period is sometimes called the 'Age of Graptolites', but cephalopods, trilobites, corals and brachiopods were also numerous. Seaweeds were the only plants. The first well-preserved jawless fish are from the Ordovician.
Graptolites • Graptolites (formally known by their scientific name Graptolithina) are extinct marine creatures that formed twig-like or net-like colonies composed of one or more branches. These colonies mostly floated freely in the sea but some may have been attached to the sea floor. Because of their branching form they may have superficially resembled seaweed but they were in fact animals.
Assemblage of brachiopod Archaeorthis from the Lower Ordovician Tetragraptus fruticosus from the Early Ordovician
Silurian Period About 434 to 410 million years ago. The first fossil evidence of land plants and animals (e.g. scorpions) is from this period. Brachiopods and graptolites were abundant. Eurypterids were fresh-water 'scorpions' that evolved to become the largest arthropods of all time (more than 2 meters long).
Cincinnatian Crinoids http://keyword.netscape.com/ns/boomframe.jsp?query=Crinoid+pictures&page=1&offset=0&result_url=redir%3Fsrc%3Dwebsearch%26requestId%3D283be23f7c782f82%26clickedItemRank%3D5%26userQuery%3DCrinoid%2Bpictures%26clickedItemURN%3Dhttp%253A%252F%252Fdrydredgers.org%252Fcrinoid5.htm%26invocationType%3D-%26fromPage%3DnsBrowserRoll%26amp%3BampTest%3D1&remove_url=http%3A%2F%2Fdrydredgers.org%2Fcrinoid5.htm
Crinoids are known as sea lilies because they live on a stem and have a flower-like body. They are analogous to starfish with a stem. Although still existing but uncommon in the oceans today, they were very abundant in shallow tropical seas during the Paleozoic. Some Mississippian rocks contain so many broken-up fossil crinoids that the Mississippian became known as the Age of Crinoids. The most common crinoid fossils are the individual button-like plates that made up the stem. Crinoid fossils can be found in the Ordovician, Silurian, Devonian, Mississippian, and Pennsylvanian rocks of Kentucky.
Devonian Period About 410 to 354 million years ago. Sponges, corals and brachiopods were abundant. The Devonian Period is often called the 'Age of Fishes' because of the evolution and spread of sharks and bony fish. The Devonian is also distinctive for the first appearance of insects and spiders. Amphibians appeared late in the period, as did ferns, horsetails and seed-ferns.
The Devonian Period 408-360 http://keyword.netscape.com/ns/img.jsp?img=http%3A%2F%2Fgpc.edu%2F%7Epgore%2Fmyphotos%2Ffossils%2Fbrachiopods.gif&query=paleozoic+life+forms&siteUrl=http%3A%2F%2Fgpc.edu%2F%7Epgore%2Fgeology%2Fgeo102%2Fdevonian.htm&thumbUrl=http%3A%2F%2Fimages-partners.google.com%2Fimages%3Fq%3Dtbn%3AohX8fOyRWhoJ%3Agpc.edu%2F%7Epgore%2Fmyphotos%2Ffossils%2Fbrachiopods.gif&h=233&imgWr=wr
Pleuroceras Ammonite Cleoniceras Ammonite Scaphites Conradi Ammonite
Ammonites are the ancient equivalent to the modern-day chambered Nautilus. These sea faring squids built a chambered shell in which they would pump air into the empty chambers and float at different levels of the ocean in search of food. This unique ability to float at different depths of the ocean is what inspired Jules Vern (the famous science fiction writer) to call the first submarine the Nautilus. Ammonites lived approximately 400 million years ago.
Fossil brachiopod Mucrospirifer arkonensis in life position from the Devonian of Arkona, Ontario.
Eight edrioasteroids (Krama devonicum) along with bryozoa of the genus Hederella encrust a pelecypod of the genus Grammysia. This is a reconstruction of an actual fossil from the Devonian of Arkona, Ontario. Title: Devonian life - Edrioasteroids on Pelecypod
