Fossil types and uses

1. Under the guidelines of
Prof. P Madesh.
By Hemanth kumar N
and
Jeffri. J
DoS in Earth Science,
Manasagangothri.

2. Fossil.
Fossil, remains or imprints of plants or
animals preserved from prehistoric times by
the operation of natural conditions. Fossils
are found in sedimentary rock, asphalt
deposits, and coal and sometimes in amber
and certain other materials. The scientific
study of fossils is paleontology.

3. Types of Fossil.
Fossils have broadly classified in to three types on
the basis of their formation.
1. Actual remains
2. Imprints
3. Petrification

4. Actual remains
 Bones
 teeth
 Shells
 Amber
 Frozen in ice.
In this type the remains of soft and hard parts of the
organism won’t alter.

5. Imprints
 Molds or Casts in mud, sand and etc… that turn to
rock.
 Imprint fossils are formed from an organism moving in
some way, leaving behind a trace or track. These tracks
are preserved when the clay/silt dries slowly and is
covered by other sediment. Plants can also leave
imprint fossils when they are covered by sediment. The
leaf tissue degrades, leaving an imprint of where the
leaf once was.

6. Petrification.
 Petrified fossils result from per mineralization, the
replacement of once-living matter by minerals.
Solutions containing silicates, carbonates, iron or
other minerals seep into the gaps and spaces between
the cells, first encasing the cells and eventually
replacing the cells themselves. Over time, minerals
entirely replace the organic material, creating a
petrified fossil.

7. On the basis of the fossils distribution, occurrence
and by their characteristics the fossils have divided
into different types.
 Body fossils:
Well preserved entire organism unaltered and altered
hard parts and naturally formed moulds and casts are
classed has body fossils. Body FossilsBody Fossils
Trilobite
CrinoidCrinoid
Horseshoe crabHorseshoe crab

8.  Chemical fossils.
Well preserved palaeoproteins and amino acids and
structures resulting from recrystallization and
carbonization process are grouped as chemical fossils.

9. Trace fossils:
Footprints, trails, burrows and tubes, coprolites
and fossilized eggs are termed as trace fossils and
they also known as Ichnofossils.

10.  Derived fossils:
Fossils whose original home was in some older bed and
whose worn and rounded surface, and perhaps different
means of preservation or content of matrix distinguishes
them from the contemporaneous fossils with which they
may be mixed are termed as derived fossils or Reworked
fossils.

11.  Living fossils:
Fossils which range from ancient time upto the present
day without any change in their primitive characters are
known as living fossils.

12.  Remaine fossils:
Organic materials which have been rolled and abraded,
accumulating over a considerable period before their
deposition are termed as Remaine fossils.

13.  Facies fossils:
Dissimilar assemblage of fossils which are controlled by
environment and restricted to certain sedimentary
environment are known as facies fossils.

14.  Pseudo fossils:
Certain structures of sedimentary or tectonic origin which
resembles fossilized organic remains are termed as Pseudo
fossils.
(dendrite made by a mineral)

15. Uses of fossils:
 Study of chronostratigraphy:
It is concern with the age of strata and their time relation.
 Biostratigraphy:
The fossils contents of beds are used in interpreting the
historical sequence.
 Index fossil and correlation of rocks:
Certain animal or plant remains are so characteristics of
certain geological origin that they are called as index
fossils. They used in correlating in other areas.

16.  Study of paleogeography:
The adaptation of organisms are characteristics of
particular environment hence those shown by fossil forms
may indicate the extent and boundaries of formers land,
water deltas, mountains, deserts, lake, rivers, shorelines
and the position of deep and shallow seas.
 Study of palaeoclimate:
The variation of temperature and the degree of moisture is
perhaps most clearly indicate by fossil plant and animals.
 Study of paleoecology:
The study of ancient organisms in relation to their total
physical, chemical and biological environment.

17.  Study of organic evolution:
No line of evidence more forcefully and clearly supports the
fundamental postulate of evolution descent with
accumulative modifications.
 Use of fossils in the discovery of new deposits of coal and
petroleum.
Important coal deposits are normally associated with sedimentary bed
containing plant fossils deposited in lake basin during the upper
Paleozoic times in India south America south Africa Madagascar and
Australia.
 Study of paleogeophysic:
Fossils play an important role in the study of paleogeophysics
they can be used to determine spatial relationship of the earth
and the moon, the length of days and years, earths force of
gravity and paleotides or ancient tidal force during the past.

18.  Study of paleoneurology;
Under a very resent branch paleoneurology the study of
endocranium of the fossil fauna is done basing research on
natural or artificial endocranial moulds.
 Micro fossils:
Microfossils data can be used in the study of palaeo currents of
sea. The presence of microfossils in shallow water sediments
which lived in deep water, Indicates a global change in the sea
level. The study of microfossils has been helpful in the
evaluation of the conditions in which petroleum deposits have
been formed. The study of microfossils is very important for
petroleum prospecting. Certain characters of microfossils like
color, outer shell composition etc. gives an idea about type of
petroleum deposition present.

19. Conclusion.
 Study of fossils have been given a data about the past
life on the earth surface.
 By studying the these fossils will help in
understanding the evolutionary trends in life.
 The fossil studies gives the key to the past
environment.

20. References
 palaeontology, evolution and distribution by….P.C.JAIN
and M.S.ANANTHRAMAN.
 Microfossils by Dr. K. Kathal.
 Internet resource
 https://sciencing.com/five-different-types-fossils-7152282.html
 Slide share.
 Wikipedia.