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PALAEONTOLOGY
TYPES OF FOSSILS
AND
FISSION TRACK
DATING
FOSSILS:
Fossils derived from the latin word
Fossilis means TO DIG.
Fossils are remains and impressions of
organisms preserved from the
geological past.
TYPES OF FOSSILS:
 ENTIRE ORGANISM PRESERVED
 ORIGINAL HARD PARTS OF INVERTEBRATES
PRESERVED
 SKELETON PRESERVED
 ALTERED HARD PARTS OF ORGANISM
PRESERVED
 TRACES OF ORGANISM PRESERVED
ENTIRE ORGANISM PRESERVED:
 In a cotinuous dry or cold regions all organic
remains even the softer body parts, may
remain unchanged for a long time under
favourable conditions.
 Organisms preserved in a medium that
protects them from bacterial decay.
EXAMPLES:
 Insects preseved in AMBER
 WOOLY MEMMOTH in siberia
 MESTODON from california
ORIGINAL HARD PARTS PRESERVED:
 In case of invertebrates animals the harder
parts such as shells,spicules get preserved and
fossilised.
 Example:
Spicules of sea urchin.
SKELETON PRESEVED:
 Skeleton of the vertebrates make perfect
fossils because they could be preserved in
their original shapes and structure.
 Example:
Fossil of perch.
ALTERED HARD PARTS PRESERVED:
Original hard parts of an oganism get
completely altered due to:
 Carbonisation:
Due to disintigrating soft parts of a body leave
behind a thin film of carbon,so exact body
outline obtained.
Petrifaction:
When the mineral rich water penetrates
through the pores made by decomposition of
the organic matter of the harder parts the
minerals gets deposited in these pores this is
called petrifaction.
Example:
Petrified forest of yellow stone national
park.
Arizona painted desert of USA
Mineralisation:
Sometimes certain structures of the fossil
remains are replaced by a specific minerals,
this is called mineralisation.
 Example:
Iron silicate replace the test of foraminifera
and shell of molluscans.
TRACES OF ORGANISM PRESERVED:
 In this case organism left certain impressions
or marks in certain hard media such as rocks.
Mold:
Impression of an organism in surronding
material is called mold.
External Mold:
Shells of an organism buried in a sediment or
mud ,which in course of time becomes
hardened,later orgaism decay,organic
material is removed by percolating acidified
water and a cavity is formed called extrnal
mold.
Internal Mold:
later that cavity of part is filled with mud or
sediments or minerals before the shell is
disolve by percolating water now mold is
called Internal mold.
Cast:
Fossils formed when an animals or other
organisms dies,its flesh decay and its bones
deteriorate due to chemical
reactions,minerals enters into the cavity
gradually resulting in Cast.
Tracks:
Impressions of feet of passing animal on mud
and wet sand covered by the sediment before
they diturbed ,are called Tracks.
 Example:
Footprints of dinosaurs on red stone of
connecticut valley in USA.
Trails:
Irregular markings of moving animals on
sedimentary rocks called Trails.
 Example:
Crawling of worm and snail.
Burrows:
Some animals live in burrows ,tubes and hole
in the ground, wood or rock presence of
such burrows in sedimentary rocks of ancient
past are called fossil burrows.
Borings:
Holes made by animals for the sake of food or
shelter on wood and rocks called fossil
borings.
Coprolites:
Coprolites are fossilised feaces of ancient
animals ,that provide information about food
and feeding habits of fossil animal.
Gestroliths:
These are the hard stony pieces found from
stomach of ancient reptiles and fishes.
FISSION TRACK
DATING
FISSION TRACK DATING:
Fission track dating is a radiomatric
technique base on analyses of damage
trails or tracks left by fission fragments in
certain uranium bearing minerals and
glasses.
It is a single crystal technique.
ROCKS SUITABLE FOR THIS DATING:
 Apatite
 Zircon
 Granite
 Pegmatites
FISSION TRACK DATING:
The age of sample can be determined
from the:
 Number of fission track present.
 Amount of uranium sample contain .
Older sample greater number of tracks.
METHOD:
 The sample are polished.
 Etched with a chemical that bring
about a track.
 Tracks are counted.
 Then sample heated.
 Anealing the track.
ANNEALING ZONE:
 Annealing zone for apatite:
Between 6o and 120 c
 Annealing zone for zircon:
390-170c
AIMES OF FISSION TRACK:
 Understanding the evolution of
mountain belts.
 Determining the source or provenance
of sediments.
 Studying the thermal evolution
of basin.
 Determining the age of poorly
dated strata
THANK YOU

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Palaeontology

  • 3. FOSSILS: Fossils derived from the latin word Fossilis means TO DIG. Fossils are remains and impressions of organisms preserved from the geological past.
  • 4. TYPES OF FOSSILS:  ENTIRE ORGANISM PRESERVED  ORIGINAL HARD PARTS OF INVERTEBRATES PRESERVED  SKELETON PRESERVED  ALTERED HARD PARTS OF ORGANISM PRESERVED  TRACES OF ORGANISM PRESERVED
  • 5. ENTIRE ORGANISM PRESERVED:  In a cotinuous dry or cold regions all organic remains even the softer body parts, may remain unchanged for a long time under favourable conditions.  Organisms preserved in a medium that protects them from bacterial decay.
  • 6. EXAMPLES:  Insects preseved in AMBER  WOOLY MEMMOTH in siberia  MESTODON from california
  • 7.
  • 8.
  • 9. ORIGINAL HARD PARTS PRESERVED:  In case of invertebrates animals the harder parts such as shells,spicules get preserved and fossilised.  Example: Spicules of sea urchin.
  • 10.
  • 11. SKELETON PRESEVED:  Skeleton of the vertebrates make perfect fossils because they could be preserved in their original shapes and structure.  Example: Fossil of perch.
  • 12.
  • 13. ALTERED HARD PARTS PRESERVED: Original hard parts of an oganism get completely altered due to:  Carbonisation: Due to disintigrating soft parts of a body leave behind a thin film of carbon,so exact body outline obtained.
  • 14.
  • 15. Petrifaction: When the mineral rich water penetrates through the pores made by decomposition of the organic matter of the harder parts the minerals gets deposited in these pores this is called petrifaction.
  • 16. Example: Petrified forest of yellow stone national park. Arizona painted desert of USA
  • 17.
  • 18.
  • 19.
  • 20. Mineralisation: Sometimes certain structures of the fossil remains are replaced by a specific minerals, this is called mineralisation.  Example: Iron silicate replace the test of foraminifera and shell of molluscans.
  • 21.
  • 22. TRACES OF ORGANISM PRESERVED:  In this case organism left certain impressions or marks in certain hard media such as rocks. Mold: Impression of an organism in surronding material is called mold.
  • 23. External Mold: Shells of an organism buried in a sediment or mud ,which in course of time becomes hardened,later orgaism decay,organic material is removed by percolating acidified water and a cavity is formed called extrnal mold.
  • 24.
  • 25. Internal Mold: later that cavity of part is filled with mud or sediments or minerals before the shell is disolve by percolating water now mold is called Internal mold.
  • 26.
  • 27. Cast: Fossils formed when an animals or other organisms dies,its flesh decay and its bones deteriorate due to chemical reactions,minerals enters into the cavity gradually resulting in Cast.
  • 28.
  • 29. Tracks: Impressions of feet of passing animal on mud and wet sand covered by the sediment before they diturbed ,are called Tracks.  Example: Footprints of dinosaurs on red stone of connecticut valley in USA.
  • 30.
  • 31. Trails: Irregular markings of moving animals on sedimentary rocks called Trails.  Example: Crawling of worm and snail.
  • 32.
  • 33. Burrows: Some animals live in burrows ,tubes and hole in the ground, wood or rock presence of such burrows in sedimentary rocks of ancient past are called fossil burrows.
  • 34.
  • 35. Borings: Holes made by animals for the sake of food or shelter on wood and rocks called fossil borings.
  • 36.
  • 37. Coprolites: Coprolites are fossilised feaces of ancient animals ,that provide information about food and feeding habits of fossil animal.
  • 38.
  • 39. Gestroliths: These are the hard stony pieces found from stomach of ancient reptiles and fishes.
  • 40.
  • 42. FISSION TRACK DATING: Fission track dating is a radiomatric technique base on analyses of damage trails or tracks left by fission fragments in certain uranium bearing minerals and glasses. It is a single crystal technique.
  • 43.
  • 44.
  • 45. ROCKS SUITABLE FOR THIS DATING:  Apatite  Zircon  Granite  Pegmatites
  • 46. FISSION TRACK DATING: The age of sample can be determined from the:  Number of fission track present.  Amount of uranium sample contain . Older sample greater number of tracks.
  • 47. METHOD:  The sample are polished.  Etched with a chemical that bring about a track.  Tracks are counted.  Then sample heated.  Anealing the track.
  • 48.
  • 49.
  • 50.
  • 51. ANNEALING ZONE:  Annealing zone for apatite: Between 6o and 120 c  Annealing zone for zircon: 390-170c
  • 52. AIMES OF FISSION TRACK:  Understanding the evolution of mountain belts.  Determining the source or provenance of sediments.
  • 53.  Studying the thermal evolution of basin.  Determining the age of poorly dated strata