Main Topic of Paleontology (Study of Fossils or remains of living organisms), Fossils and Types of Fossils & Significance of Fossils

1. PALEONTOLOGY
FOSSILS & TYPES
USES OF FOSSILS
LECTURE NO. 1
05 DECEMBER 2020
By
KASHIF MANZOOR (PH.D SCHOLAR)
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2. INTRODUCTION TO PALEONTOLOGY
The science which deals with the study of the fossilized remains of plants and
animals found in earth’s crust OR the study of fossils is called Paleontology.
(Greek words pailos = ancient + onta = existing + logos=knowledge).
A. PALEOBOTANY: is the study of fossil plants.
B. PALEOZOOLOGY: is the study of fossil animals.
i. INVERTEBRATE PALEONTOLOGY: is the study of fossil animals without
backbones.
ii. VERTEBRATE PALEONTOLOGY: is the study of fossil animals with
backbones or vertebral column.
iii. MICROPALEONTOLOGY: is the study of fossil that are so small that they
can be studied under microscope only.
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3. 3
PALEOZOOLOGY

4. 4
MICROPALEONTOLOGY PALEOBOTANY

5. FOSSILS
The word fossil is derived from Latin word “fossilis”, meaning “dug-up”.
For many years any curious object that was dug out of the ground was
considered to be a fossil.
Today we define fossil as “the remains or relics of any organism that
lived prior to Recent times”.
Fossils are found in many forms depending upon the
a) original character of the organism,
b) the type of material in which it was buried, and
c) the chemical action to which it was subjected after burial.
Fossils may be arranged into four groups according to their method of
preservation.
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6. 6

7. TYPES
OF
FOSSILS
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8. a). ORIGINAL SOFT PARTS OF ORGANISMS
Usually only the hard parts of organisms are fossilized but, under exceptionally
favorable conditions, even the soft parts are also preserved. Organisms may be
preserved intact in a medium that protects them from decay by bacterial action.
Examples of such special media are ice, oil saturated soil, and Amber.
The best known examples of fossils preserved in ice or frozen soil are Wooly
mammoths of Siberia and Alaska. These huge elephant like mammals (with
curved tusks) apparently died due to heavy glaciation and were buried in
permafrost (frozen soil) many thousand years ago. The first such find was reported
from Siberia in 1799, more than fifty additional specimens have been
discovered since then.
The ice preservation is so perfect that skin, hairs, blood, flesh and other parts
of the body are intact.
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TYPES OF FOSSILS

9. 9
Amber is fossilized tree resin that has been appreciated for its
color and natural beauty since Neolithic times. Much valued
from antiquity to the present as a gemstone, amber is made
into a variety of decorative objects. Amber is used in jewelry.
It has also been used as a healing agent in folk medicine.

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MAMMOTHS

11. a). ORIGINAL SOFT PARTS OF ORGANISMS
The remains of an extinct Rhinoceros has been obtained from oil saturated soil
in Eastern Poland. This is rather uncommon medium of preservation but it has
resulted in well preserved skin and flesh.
Another interesting medium of preservation is amber. Prehistoric insects became
entrapped in a sticky gum like resin that exudes out from the trunk of trees. This
yellowish coloured resin is called Amber. As it dried and solidified, the insects
remain embedded in the resin as remarkably well preserved fossil which show
even histological details like the freshly preserved specimens.
Desert forms may be dried out by the hot, dry, desert winds and then buried in
shifting sands resulting into well preserved skin and bone.
The total number of fossils of soft parts of animals is, however, very small
compared to that of other methods of fossilization.
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TYPES OF FOSSILS

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RHINOCEROS

13. b). ORIGINAL HARD PARTS OF ORGANISMS
Most animals and plants have some hard parts in their bodies which are capable of
fossilization. These may be in the following forms.
I. CALCITIC REMAINS: e.g. shells of foraminifers, corals, test of echinoderms
and brachiopods (common constituent of these hard parts is mineral calcite).
II. ARAGONITIC REMAINS: shells of gastropods, pelycepods and cephalopods
(an unstable form of calcite).
III. PHOSPHATIC REMAINS: Bones of vertebrates.
IV. SILICEOUS REMAINS: e.g. Radiolarian shells and skeleton of some
sponges.
V. CHITINOUS REMAINS: exoskeleton of arthropods.
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TYPES OF FOSSILS

14. c). ALTERED HARD PARTS OF ORGANISM
The original hard structure of many organisms may undergo considerable variation
with the passage of time. These changes may come out in many different ways,
depending on the body material of the organisms, the environmental conditions
in which organisms lived and the conditions under which the remains of
organisms deposited.
1. CARBONIZATION OR DISTILLATION: Soft organic material may be
preserved by carbonization or distillation, a process in which, as time passed,
nitrogen, oxygen and hydrogen are lost and only a thin film of carbonaceous
material remains. This carbon reside may retain many of the characteristics of the
form of original organism. If the film of carbon is lost from fossil preserved in fine
grained sediment, a replica of the surface, called as impression, may still show
considerable detail. Jelly fish, fish and parts of trees have been fossilized in this
manner.
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TYPES OF FOSSILS

15. c). ALTERED HARD PARTS OF ORGANISM
II. PERMINERALIZATION OR PETRIFICATION: Often fossils become
petrified (literally turned into stones), meaning that the small internal cavities
or pores of the original structure are filled with precipitated mineral
matter. The hard parts of many organisms have been preserved by this method
and such fossils are heavy and stone like. Petrified wood is the most common
example of this type of preservation.
III. REPLACEMENT OR MINERALIZATION: This type of preservation
occurs when circulating water dissolves chemicals from bones or shells and
leaves them light and spongy. More often as chemicals are dissolved they are
replaced by others (i.e. the gaps are filled by the deposition of other mineral
bearing solution). The replacing minerals are of more than fifty types. Most
common are silica, lime, quartz, pyrites etc.
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TYPES OF FOSSILS

16. d). TRACES OF ORGANISMS
In addition to the fossils already mentioned, there are numerous other types, many
of them only traces or impressions of prehistoric life. Examples of such indirect
evidence includes;
I. MOLD: A mold is the impression of an organism in the surrounding
material. For example, when a shell or bone or other structure is buried in
sediment and then dissolved by ground water, leaving a cavity, a mold is created.
The mold reflects only the shape and surface markings of the organisms, but does
not reveal any information concerning its internal structure. Molds of thin forms,
such as leaves of plants, are called IMPRINTS.
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TYPES OF FOSSILS

17. d). TRACES OF ORGANISMS
II. CAST: If the hollow cavity or mold is subsequently filled with some mineral matter,
a natural cast is formed. This differs from petrification in that it retains only the form (or
shape) of organism but not its structure. An artificial cast is produced when the mold is
filled with liquid rubber, dental wax or plaster of paris.
III. TRACES AND TRAILS: Tracks or traces are footprints made by animals as they
walk over ground. These tracks are more likely to be preserved in arid and semi-arid areas.
Foot prints, occurring in series, however, may indicate the size and shape of foot, length
of limbs, posture and types of gait. Footprints of dinosaurs have been found in excellent
shape in the redstone of the Connecticut Valley, U.S.A.
Trails are impressions made by the bodies of organisms as they crawl over the ground.
Borings or burrows of worms and molluscs have also been preserved as fossils.
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TYPES OF FOSSILS

18. d). TRACES OF ORGANISMS
IV. GASTROLITHS: Gastroliths are smooth rounded stones found in the rib
cages of dinosaurs. These stones probably helped the dinosaurs in digestion just as
pigeons have gravel in their gizzards to crush grains. Gastroliths are found in
dinosaurs only.
V. COPROLITES: Fossil faecal pellets or casting of animals droppings are
called coprolites. Coprolites are usually found in association with the animals that
made them, and a study of fossil excretea may provide valuable information
pertaining to the food habits of these organisms.
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TYPES OF FOSSILS

19. USES OF FOSSILS
Fossils are useful in number of ways. Prehistoric man utilized fossils in an
attempt to ward off evil spirits, while medicine men of certain primitive
culture of today use fossil bones in the belief that they possess some
mysterious power of healing wounds.
The scientists, however, use fossils to recreate the geological history of earth.
Perhaps the importance of fossil is in the tracing of the development of plants
and animals. Some of the important uses are;
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USES OF FOSSILS

20. USES OF FOSSILS
I. AS STRATIGRAPHIC INDICATOR: Fossils are one of the most valuable tools
of the stratigrapher and can provide important clues to the age of rocks
containing them. It is possible to use fossils for this purpose because it has long
been known that there is a definite relationship between fossil contents of the rocks
and position of these rocks in geological column.
According to the LAW OF SUPERPOSITION, we know that in a normal
sequence of sedimentary rocks, younger strata are laid down on the top of the
older strata. Hence it follows that oldest fossils will normally be found at the
bottom of a rock sequence with younger fossils near top of the sequence. In
some cases, however, the rocks have been disturbed by crustal deformation. In these
regions, the beds may have been overturned or older rocks thrust on top of the
younger ones. If the strata in the areas are fossiliferous and if the geologist knows
the order in which the fossils normally occur in the section, he can then work out
the proper stratigraphic sequence.
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USES OF FOSSILS

21. USES OF FOSSILS
II). AS CLIMATIC INDICATOR: Fossils have been successfully used to
demonstrate the existence of different climatic conditions in the geological past.
If we find remains of tropical plants or animals in a region that has temperate or
cold climate today we assume that a tropical climate prevailed in that area at one
time. For example,
a). Fossil ferns from Greenland indicate, a much warmer climate for these
areas in other time,
b). Remains of the reef building corals have been found in Siberia. Since these
animals have always lived in warmer seas, their fossils indicate that the climate was
tropical at least during Silurian period,
c). Fossils of reindeer from France, indicate once its climate was extremely cold.
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USES OF FOSSILS

22. USES OF FOSSILS
III). AS EVIDENCE OF CHANGING GEOGRAPHIC PATTERN: Fossils have
been provided us with much information about the distribution of the seas and
land masses of the past. Certain animals such as, corals, echinoderms and
brachiopods have always lived in the sea.
The presence of these animals indicate marine deposition for the rocks containing
them. Similarly, occurrence of land plants or fossils of terrestrial animals will
indicate the presence of land masses in that particular area.
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USES OF FOSSILS

23. USES OF FOSSILS
IV). AS RECORD OF PREHISTORIC LIFE: The study of fossils has provided
us much information about the origin and evolution of organisms living today.
The knowledge is possible because all modern animals have descended from their
primitive ancestors which populated the earth in times past. By studying the record
of the changes that organisms have undergone, the paleontologist is able to work
out the family tree or evolutionary pattern of for most the present day life. It is
thus possible to determine the relationship between different groups of plants
and animals and to see how life slowly, but continuously, become progressively
more complex.
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USES OF FOSSILS

24. USES OF FOSSILS
IV). AS ECONOMIC TOOLS: Fossils not only are of value in conducting
scientific studies but have practical applications as well.
Since many of our more important resources are associated with sedimentary rocks,
fossils, when present, may be of help in locating mineral ores, coal, oil and gas
deposits. For example, mining geologist uses fossils to date the strata above and
below the rocks that contain valuable minerals. Fossil plants are commonly
associated with coal deposits. Foraminifera (important group of protozoan fossils)
are important in locating fields.
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USES OF FOSSILS

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