Transcript Document

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Fossils
Mr. Litaker
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How are fossils
created
There are five major ways in
which a fossil can be preserved.
They are:
1. Petrification
2. molds
3. impressions
4. amber and
5. sedimentary fossils
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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.
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This process usually works best in the
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fossilization of trees.
Some of the most famous petrified
trees are in California, and contain
huge rings that describe ancient
eras.
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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 a mold.
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A mold can be created in two ways.
1. An organism can deteriorate and leave a
hole showing details of its body.
2. 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.
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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!
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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.
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 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!
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Sedimentary Fossils
The sea bed contains 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.
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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.
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 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)
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Precambrian Life
There really just wasn’t any life forms!
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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.
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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. 20
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Cambrian Period
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* 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
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these were one of the most dominant life forms.
Cambrian Period
In the image above, trilobites (1) live among many species that are not normally preserved. A typical
Cambrian outcrop might produce only trilobites, brachiopods (2), mollusks (3), and crinoids (4).
Sponges Vauxia (5), Hazelia (6), and Eifellia (7); brachipods Nisusia (2); priapulid worms Ottoia (8);
trilobites Olenoides (1); other arthropods such as Sidneyia (9), Leanchoilia (10), Marella (11),
Canadaspis (12), Helmetia (13), Burgessia (14), Tegopelte (15), Naraoia (16), Waptia (17), Sanctacaris
(18), and Odaraia (19); lobopods Hallucigenia (20) and Aysheaia (21); mollusks Scenella (3);
echinoderms Echmatocrinus (4); and chordates Pikaia (22); among other oddities, including
Haplophrentis (23), Opabinia (24), Dinomischus (25), Wiwaxia (26), Amiskwia (27), and
Anomalocaris (28).
This is
A Cambrian
trilobite from
Utah
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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.
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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.
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Assemblage of brachiopod
Archaeorthis from the
Lower Ordovician
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Tetragraptus fruticosus from the
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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).
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Brachiopoda
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Bryozoan colony
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foraminifera (protozoa)
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Eurypterid, Eurypterus
remipes
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Cincinnatian Crinoids
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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
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Kentucky.
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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 seedferns.
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The Devonian Period
408-360
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Fossil ammonite Tornoceras mesopleuron
from the Devonian
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Pleuroceras
Ammonite
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Cleoniceras
Ammonite
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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.
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Jawed fish Cephalaspis
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Mucrospirifer brachiopod Fossil Shells.
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Fossil brachiopod Mucrospirifer
arkonensis in life position from
the Devonian of Arkona, Ontario.
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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
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ostracod (crustacean)
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Genoa Amphibian
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Carboniferous Period
About 354 to 298 million years
ago.
Forests of tall evergreen trees, fern-like plants,
horsetails and creepers lived in the swamps of
this period, and eventually formed much of the
Earth's coal. The period is therefore known as the
'Coal Age'. It is also known as the 'Age of
Amphibians', as these were the dominant land
animals. Corals and brachiopods were abundant
in the sea. Reptiles and winged insects appeared
on land.
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Mississippian & Pennsylvanian
From 354-325 MYBP
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From 325-298 MYBP
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Rhacopteris Leaves fossil
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Permian Period
About 298 to 251 million years ago.
This was a time of severe climatic variation
and plant and animal extinctions.
Deciduous trees and conifers became
abundant, mammal-like reptiles and
modern insects such as cicadas and beetles
emerged; ammonites, brachiopods,
bryozoans and corals flourished in the seas.
The period ended with the greatest of all
'mass extinctions', 90% of the many plants
and animals becoming extinct or much less
diverse.
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It affected many groups of organisms
in many different environments, but it
affected marine communities the
most by far, causing the extinction of
most of the marine invertebrates of
the time. Some groups survived the
Permian mass extinction in greatly
diminished numbers, but they never
again reached the ecological
dominance they once had, clearing
the way for another group of sea life
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On land, a relatively smaller
extinction of diapsids and synapsids
cleared the way for other forms to
dominate, and led to what has been
called the "Age of Dinosaurs".
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The global geography of the Permian included
massive areas of land and water. By the beginning
of the Permian, the motion of the Earth's crustal
plates had brought much of the total land
together, fused in a supercontinent known as
Pangea. Many of the continents of today in
somewhat intact form met in Pangea (only Asia
was broken up at the time), which stretched from
the northern to the southern pole. Most of the rest
of the surface area of the Earth was occupied by a
corresponding single ocean, known as
Panthalassa, with a smaller sea to the east of
Pangea known as Tethys Sea.
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Dimetrodon - ancestor of the
mammals belonged to the family
called Pelycosaurs, which had
both mammal and reptile
characteristics. Dimetrodon
preceded the earliest dinosaurs
by more than 40 million years
but physically it looked a lot like
one. It is often referred to as
mammal-like reptile, based on
characteristics of the skull and
dentition. Dimetrodon was a
dominant carnivore, the largest
one of the Permian period. It
was a predacious reptile that
TIME - 280 - 260 MYA, Early Permian period. was on the top of the food chain
RANGE - Russia, E. Europe. USA Texas
during the early Permian.
DIET - Smaller reptiles and other small vertebrates.
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Up to 6ft (2m) long.
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Pleistocene, North America, Great Lakes region,
Ice Age
Mastodon Bull
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