Fossilization & conditions required for it.

Fossilization & conditions required for it.

1. PROCESSES OF FOSSILIZATION & CONDITION REQUIRED FOR IT DR. MUHAMMAD TARIQ DEPARTMENT OF ZOOLOGY GOVT. COLLEGE OF SCIENCE, WAHDAT ROAD, LAHORE

2. FOSSILIZATION The process of a once living organism becoming a fossil is called   Fossilization .

3. FOSSILIZATION…. contd …. Fossilization is a very rare process : Of all the organisms that have lived on Earth, Only a very low percentage of them ever become fossils .

4. For animals that lack hard shells or bones, fossilization is even more rare.

5. As a result, the fossil record contains many animals with shells, bones, or Other hard parts, & few softbodied organisms .

6. There is virtually no fossil record of jellyfish, worms, or slugs. Insects , which are by far the most common land animals, are only rarely found as fossils.

7. Because mammal teeth are much more resistant than other bones , A large portion of the mammal fossil record consists of teeth .

8. This means the fossil record will show many organisms that had shells, bones or other hard parts &

9. Will almost always miss the many soft-bodied organisms that lived at the same time.

10. TYPES OF FOSSILIZATION

11. TYPES OF FOSSILIZATION PERMINERALIZATION / PETRIFICATION REPLACEMENT /MINERALIZATION DISTILLATION/CARBONIZATION TRACES OF ORGANISMS

12. TYPES OF FOSSILIZATION ( i ) PERMINERALIZATION/PETRIFICATION A type of fossilization in which minerals are deposited into the pores of the original hard parts of an organism .

13. TYPES OF FOSSILIZATION ( i ) PERMINERALIZATION/PETRIFICATION The most common method of fossilization is   permineralization . After a bone, wood fragment, or shell is buried in sediment,

14. TYPES OF FOSSILIZATION ( i ) PERMINERALIZATION/PETRIFICATION It may be exposed to mineral-rich water that moves through the sediment. This water will deposit minerals into empty spaces, producing a fossil.

15. TYPES OF FOSSILIZATION ( i ) PERMINERALIZATION/PETRIFICATION E.g., Fossil Dinosaur bones, petrified wood, & many marine fossils were formed by permineralization .

16. Fig. Petrified wood,

17. Fig. Petrified Trees

18. FIG.2. Dinosaur fossils found in Alberta, Canada .

19. TYPES OF FOSSILIZATION ( i ) PERMINERALIZATION/PETRIFICATION This type of fossilization takes place when mineral-bearing ground waters infiltrate porous bone, shell, or plant material.

20. TYPES OF FOSSILIZATION ( i ) PERMINERALIZATION/PETRIFICATION With the passing of time, these underground waters will deposit their mineral content in the empty spaces of the hard parts,

21. TYPES OF FOSSILIZATION ( i ) PERMINERALIZATION/PETRIFICATION Thus making them heavier & more resistant to weathering.

22. Fig.4. Fossil Specimen of Ammonite. (Another fossil reminded the Greeks of the coiled horns of a ram(adult male sheep). The Greeks named them ammonites after the ram god  Ammon ) .

23. Fig.5. Fossil Specimen of Elephant skull

24. REPLACEMENT / MINERALIZATION In some cases, the original shell or bone dissolves away & is replaced by a different mineral.

25. REPLACEMENT /MINERALIZATION E.g., Shells that were originally calcite may be replaced by dolomite, quartz, or pyrite. If quartz fossils are surrounded by a calcite matrix, the calcite can be dissolved away by acid,

26. REPLACEMENT /MINERALIZATION Contd …. Leaving behind an exquisitely preserved quartz fossil.

27. REPLACEMENT/MINERALIZATION This occurs when the original hard parts of an organism are removed After being dissolved by circulating groundwater.

28. REPLACEMENT/MINERALIZATION As the hard parts are dissolved there is almost a simultaneous deposition of other mineral substances in the resulting voids.

29. REPLACEMENT/MINERALIZATION In some replaced fossils the original structure will have been destroyed by the replacing minerals.

30. REPLACEMENT/MINERALIZATION However , in others, as in the case of certain mineralized tree trunks, The remains may be preserved in minute detail.

31. CARBONIZATION & DISTILLATION This process takes place as the organic material slowly decays after burial. During the process of decomposition, the organic matter gradually loses its gases & liquids,

32. CARBONIZATION & DISTILLATION…. contd … leaving behind a thin film of carbon . This is the process by which coal is formed, &

33. CARBON FOSSILS… contd …. The thin layer of carbon left behind

34. CARBON FOSSILS… contd …. Can show an organism’s delicate parts like leaves or plant E.g . Fern fossil 300 MYs old.

35. CARBONIZATION & DISTILLATION…. contd … Carbonized plant fossils are commonly found in many coal deposits .

36. Fig.3, Fossilized leaf.

37. CARBONIZATION & DISTILLATION…. contd … E.g., In addition, the remains of fish, graptolites, & reptiles have been preserved by carbonization .

38. TRACES OF ORGANISMS These are remains of traces or imprints of once living organisms. Examples include molds & casts of organisms.

39. External Mold

40. INTERNAL MOLDS : Molds of the underside of the shell may be left on the surface of rock That formed when sand or mud filled the inside of the shell.

41. Internal Mold

42. Fig. Mold fossil of a bivalve

43. Cast fossil of a whelk (a large marine snail-carnivorous gastropod-with shell

44. Casts fossils….. contd … E.g., Many mollusks i.e. clams , snails, octopi & squid , are commonly found as casts.

45. TRACES OF ORGANISMS….. contd …… If for instance a shell had been pressed down into the ocean bottom before the sediment had hardened into rock,

46. TRACES OF ORGANISMS….. contd … It may have left the impression of the exterior of the shell. This impression is called a Mold . If at some later time this mold should become filled with another material, This might produce a Cast .

47. TRACES OF ORGANISMS….. contd … A cast formed in this manner will show the original external features of the shell. Objects of this type are called external molds If they show the external features of the hard parts,

48. TRACES OF ORGANISMS….. contd … & Internal molds if the nature of the inner parts is revealed. The tracks, trails & burrows can be among the most useful – & puzzling – of all fossils.

49. TRACES OF ORGANISMS….. contd … Some of these, especially footprints, may indicate not only the type of animal that left them But may also furnish information about how & where the animal lived.

50. TRACKS AND TRAILS Tracks are footprints, paw prints or claw prints

51. TRACKS AND TRAILS Which become covered with sediment before they are washed away by rain or wave.

52. Fig. Fossilized footprint of an unidentified dinosaur.

53. TRACES OF ORGANISMS….. contd … For example , the study of a series of the dinosaur tracks would not only indicate the size & shape of the dinosaur’s foot, But might also give indication as to the weight & length of the animal.

54. Fig. Tyrannosaurus rex fossil footprint

55. TRACES OF ORGANISMS….. contd … In addition, the type of rock containing the tracks would probably help to determine the conditions under which the animal had lived.

56. EXCEPTIONAL PRESERVATION Two of the most famous examples of soft organism preservation are The Burgess Shale in Canada & The Solnhofen Limestone in Germany.

57. Fig . Frozen mammoths, in amber is a body fossil.

58. Fig. Frozen insects in amber are all body fossils.

59. EXCEPTIONAL PRESERVATION The Burgess Shale is 505 MY,s old & Records the first explosion of shelled organisms in Earth’s oceans. Many of the Burgess Shale fossils are bizarre animals (unconventional or unusual) That seem unrelated to any other animal group.

60. EXCEPTIONAL PRESERVATION The Solnhofen Limestone is 145 MY,s old & contains fossils of many soft-bodied organisms That are not normally preserved, such as jellyfish.

61. EXCEPTIONAL PRESERVATION The most famous Solnhofen fossil is  Archaeopteryx , one of the earliest birds. Although it resembles a dinosaur fossil, impressions of feathers can clearly be seen ( Fig.11 ).

62. Fig.11 : Fossils from Lagerstätten :  Archaeopteryx  

63. Fig. 11: Fossils from Lagerstätten : Anomalocaris . Anomalocaris was an enormous predator (one meter long) that lived 500 MYA.

64. CONCLUSIONS Fossils are the remains & traces of ancient plants & animals. For fossilization to take place, The original organism or plant must posses hard parts ,

65. CONCLUSIONS The organic remains must escape destruction immediately after death,

66. CONCLUSIONS & rapid burials must take place in a material capable of retarding decomposition.

67. CONDITIONS REQUIRED FOR FOSSILIZATION In order for fossilization to take place, the following conditions must be fulfilled: i ). Possesion of hard parts ii ). Escape immediate destruction after death i ii). Rapid burial

68. CONDITIONS REQUIRED FOR FOSSILIZATION I) . POSSESION OF HARD PARTS The organism should posses hard parts e.g. bones, teeth, shells or woody tissue of plant. However , even though the hard parts are normally required,

69. CONDITIONS REQUIRED FOR FOSSILIZATION i ). POSSESION OF HARD PARTS under unusually favorable conditions of preservation, such fragile objects such as e.g. jellyfish & insects have become fossilized.

70. CONDITIONS REQUIRED FOR FOSSILIZATION ii). ESCAPE IMMEDIATE DESTRUCTION AFTER DEATH The organic remains must escape immediate destruction after death. If the hard parts of an organism should be crushed, eroded or otherwise greatly changed ,

71. CONDITIONS REQUIRED FOR FOSSILIZATION ii). ESCAPE IMMEDIATE DESTRUCTION AFTER DEATH This could result in the alteration or complete destruction of the fossil record of that plant or animal.

72. CONDITIONS REQUIRED FOR FOSSILIZATION iii). RAPID BURIAL Rapid burial must take place in a material capable of retarding decomposition. In general the type of material in which the remains are buried

73. CONDITIONS REQUIRED FOR FOSSILIZATION iii). RAPID BURIAL usually depends on where the organisms lived e.g . the bones and shells of marine animals are common as fossils Because they fell on the ocean floor after death.

74. CONDITIONS REQUIRED FOR FOSSILIZATION iii). RAPID BURIAL Under such conditions they were covered by soft mud which later hardened to shales & limestone of later geologic time.

75. CONDITIONS REQUIRED FOR FOSSILIZATION iii). RAPID BURIAL The soft muds are less likely to damage the organism (organic remains). Certain fine-grained rocks e.g . limestone have faithfully preserved delicate specimens as birds, insects & jelly fishes.