Fossils & it's types
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Body fossils and trace fossils are the two main types of fossils. Body fossils are the direct remains of organisms preserved in rock, such as bones, teeth, shells, and leaves. They provide direct evidence of past life. Trace fossils are evidence of organism activity, rather than the organism itself, and include tracks, trails, burrows, nests, and coprolites. Trace fossils provide indirect evidence of past life and insights into organism behavior. Both body fossils and trace fossils are important sources of information about Earth's evolutionary history and past environments.
Fossils & it's types
- 1. FOSSILS, & THEIR TYPES DR. MUHAMMAD TARIQ DEPARTMENT OF ZOOLOGY GOVT. COLLEGE OF SCIENCE, WAHDAT ROAD, LAHORE
- 2. LEARNING OUTCOMES After studying this topic, students will be able to define & explain……. •What are Fossils? •Types of Fossils •Body Fossils •Trace Fossils •Distinguish between body fossils & trace fossils. •Uses/Applications of Fossils
- 3. WHAT ARE FOSSILS? •Fossils (L. fossilis, to dig) •meaning an object that has been dug up from the ground. •are evidence of plants & animals
- 4. WHAT ARE FOSSILS? •Fossils (L. fossilis, to dig) •that existed in the past & have become incorporated into the earth’s crust (e.g., as rock or mineral) (Fig.1).
- 5. FIG.1. Paleontological Evidence of Evolutio-nary Change. • Fossils, i.e. Trilobite (Griffithides), are direct evidence of evolutionary change. • Trilobites existed ca. 500 MYA & became extinct about 250 MYA.
- 6. FIG.2. Dinosaur fossils found in Alberta, Canada.
- 8. 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
- 9. Fig.5. Fossil Specimen of Elephant skull
- 10. • Definition: The remnants, impressions, or traces of an animal or plant that has been preserved in the rocks (formed Earth’s crust) during past geologic age.
- 11. • The complex of data recorded in fossils worldwide—known as the Fossil Record— • Fossil record is the primary source of information about the history of life on Earth.
- 12. Types of Fossils •Body Fossils: •Trace Fossils:
- 13. BODY FOSSILS • Body fossils, are the fossilised remains of an animal or plant, • like bones, shells & leaves.
- 14. BODY FOSSILS…contd… • These can be mould and cast fossils, • Like most of the fossilised dinosaur skeletons
- 18. Body Fossils…contd… • & Big bones we see, replacement fossils, • like petrified wood, or whole body fossils –
- 21. Body Fossils…contd… • Mammoths caught in ice, • or Insects trapped in amber.
- 22. Fig. Frozen mammoths, in amber is a body fossil.
- 23. Fig. Frozen insects in amber are all body fossils.
- 24. Body Fossils • Body fossils, are the fossilised remains of an animal or plant, • like bones, shells & leaves. • These can be mould & cast fossils,
- 25. Body Fossils • Body fossils are the remains of living organisms & • are direct evidence of past life.
- 26. Body Fossils…contd…. • Usually only hard tissues are preserved, • E.g., shells, bones, or carapaces.
- 27. Body Fossils…contd…. • In particular environmental conditions the soft tissues may fossilize • but this is generally a rare occurrence.
- 28. Body Fossils…contd…. • Most body fossils are the remains of animals • that have died, but death is not a prerequisite,
- 29. Body Fossils…contd…. • Since some body fossils represent parts of an animal • that are shed during its lifetime.
- 30. Body Fossils…contd…. • E.g., Trilobites shed their exoskeleton • as they grow & these molts may be preserved in the fossil record.
- 32. • Explain that a mold is a fossilized hollow impression of a plant or animal. • A cast fossil forms when a mold is filled in with sediment.
- 33. • Trace fossils are fossilized nests, eggs, tracks, coprolites (dinosaur poop=rear part), etc. • Trace fossils show evidence of dinosaur activity in the environment.
- 34. MOLDS & CASTS • Body fossils include molds & casts. • A mold is the imprint left by the shell on the rock that surrounded it.
- 35. • There are two types of molds. They are: • External Mold • Internal Mold
- 36. External Mold: • It is a mold of the outside of the shell. • Each time we break a shell or bone out of the rock, an external mold is left behind.
- 37. External Mold
- 38. 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
- 39. Internal mold
- 40. Molds fossils is Formed: • A fossil mold is created when a shell or other structure is buried in sediment & • then dissolved by
- 41. MOLDS FOSSILS: • In such cases, the original bone or shell dissolves away, • Leaving behind an empty space in the shape of the shell or bone. • This depression is called a Mold.
- 43. Fig. Mold fossil of a bivalve
- 45. Molds fossils…..contd… • E.g., Many mollusks i.e. clams, snails, octopi & squid, • are commonly found as molds
- 46. Mold Fossils • Definition: A fossilized impression made in the substrate; a negative image of the organism.
- 47. Molds fossils…..contd… • The mold reflects only the shape & surface markings of the organism. • It doesn’t reveal any information about its internal structure.
- 48. Casts fossils: • Cast fossils are created if the hollow spaces of a mold • are later filled with mineral matter.
- 49. Casts fossils are created • If the hollow spaces of a mold • are later filled with sediment/mineral matter.
- 50. Casts fossils….contd… • To form a match- ing cast in the shape of the original organism.
- 51. Cast fossil of a whelk (a large marine snail-carnivorous gastropod-
- 52. Casts fossils…..contd… • E.g., Many mollusks i.e. clams, snails, octopi & squid, • are commonly found as casts.
- 55. • Casts are replicas of the shell or bone that are formed from external or internal molds.
- 56. • Casts can be produced naturally, • But paleontologists can also produce casts from molds with latex rubber or even modeling clay.
- 57. • These artificial casts can provide extra information about the fossils under study.
- 58. • Trace fossils are marks left by an animal or plant that has made an impression.
- 59. TRACE FOSSILS • These fossils include nests, burrows, footprints or any other markings of the animal’s time on the earth.
- 60. TRACE FOSSILS ….contd……. • The structure of the animal or plant remains as a mineral form.
- 61. TRACE FOSSILS ….contd……. • The colours of the minerals that replace the form can be dazzling.
- 62. TRACE FOSSILS ….contd • Sometimes they are made into art & jewellery.
- 63. Trace Fossils/ICHNOFOSSILS • Trace fossils are rocks that have preserved evidence of biological activity.
- 64. Trace Fossils…contd… • They are not fossilized remains, • Just the traces of organisms.
- 65. Trace Fossils…contd… • The imprint of an ancient leaf or footprint is a trace fossil.
- 66. Trace Fossils…contd… • Burrows can also create impressions in soft rocks or mud, • leaving a trace fossil.
- 67. TRACE FOSSILS…contd…. • Trace fossils are the preserved impressions of biological activity.
- 68. TRACE FOSSILS…contd…. • They provide indirect evidence for the existence of past life.
- 70. TRACE FOSSILS..CONTD… • They are the only direct indicators of fossil behaviour.
- 71. TRACE FOSSILS..CONTD… • As trace fossils are usually preserved in situ
- 72. TRACE FOSSILS..CONTD… • They are very good indicators of the past sedimentary environment.
- 73. TRACE FOSSILS..CONTD… • Trace fossils made by trilobites have provided an insight into trilobite life habits,
- 74. TRACE FOSSILS..CONTD… • In particular walking, feeding, burrowing, and mating behaviour.
- 76. COPROLITES • Coprolites are fossilized animal feces. • They may be considered as a form of trace fossils
- 78. • Recording the activity of an organism.
- 79. COPROLITES…contd… • In some coprolites recognizable parts of plants & animals are preserved,
- 80. Fig. coprolites (trace fossils) - They show us how an animal lived
- 81. COPROLITES…contd… • Providing information about feeding habits & • The presence of coexisting organisms.
- 83. CARBON FOSSILS • All living things contain an element i.e. carbon. • When an organism dies & is buried in sediment,
- 84. CARBON FOSSILS..contd… • The materials that make the organism break down • & Eventually only the carbon remains.
- 86. CARBON FOSSILS…contd…. • The thin layer of carbon left behind
- 87. CARBON FOSSILS…contd…. • Can show an organism’s delicate parts like leaves or plant • E.g. Fern fossil 300 MYs old.
- 89. TRACKS AND TRAILS • Tracks are footprints, paw prints or claw prints
- 90. TRACKS AND TRAILS • Which become covered with sediment before they are washed away by rain or wave.
- 91. Fig. Fossilized footprint of an unidentified dinosaur.
- 92. TRACKS AND TRAILS..contd.. • Trails are not usually made by feet, • But by tentacles, the crawling patterns of snakes & worms,
- 93. TRACKS AND TRAILS..contd.. • or the boreholes of prehistoric beetles. • E.g., Pic. features a Tyrannosaurus rex track.
- 94. Fig. Tyrannosaurus rex fossil footprint
- 95. TRACKS AND TRAILS..contd.. • These give information about how animals behaved • when they were alive, i.e. how they moved & how & where they fed.
- 96. TRACKS AND TRAILS..contd.. • Trackways, which are several footprints together,
- 97. TRACKS AND TRAILS..contd.. • Sometimes include impressions made by another part of the creature, • Such as its tail dragging behind it.
- 98. Fig. Tyrannosaurus rex fossil footprint
- 99. Gastroliths are stones swallowed by certain animals to aid digestion.
- 100. PSEUDOFOSSILS • Sometimes watery solutions of various minerals speed through the sediments
- 101. PSEUDOFOSSILS…contd… • & It takes the shape of some plant part or animal. • Their study shows that
- 102. PSEUDOFOSSILS…contd… • They are neither plants nor animals. • Such fossils are called pseudofossils.