Fossils & Fossilization.ppt
- 1. FOSSILS • Dug up; Direct way of past study. • Excavated from sedimentary rocks; Remains preserved in rocks. • The remains of creatures that lived and died and were buried in sediments and later solidified into rocks. • The remains of animals that lived prior to recent times at least 10-15 thousand years. • Remains of organisms which have acquired a physicochemical stability with regards to their environments.
- 2. FOSSILS Fossils are the organic remains which are naturally preserved, have physicochemical stability with their environments and show the exact morphology of that organic remains.
- 3. Fossils are the organic remains of organisms which are naturally preserved, have physicochemical stability with their environment and show the exact morphology of those organic remains.
- 4. FOSSILIZATION Fossilization includes all the process occurred during the transformation of organic remains into fossils in sediments, or any other comparable medium.
- 5. FOSSILIZATION • Animal dies and normally eaten by scavengers or decomposed by bacteria. • Mud, slide, sandstorm, flood cause to bury the animal quickly. • Animal may be entombed by ice, tar, resin. • Animal protects to decay and buries for myr. • Mineral seepage, pressure and others, organisms change (distortion, incomplete filling, complete rock conversion). Fossilization depends on different factors:
- 6. FACTORS FOR FOSSILIZATION NATURE OF ANIMALS ENVIRONMENTS MARINE ENVIRONMENTS LAND ENVIRONMENTS SOFT PARTS HARD PARTS Floods Bogs Natural Petroleum Seeps Amber Caves and Under Ground Caverns Falls of Volcanic Ash Ice or Frozen Soil Deserts
- 7. Fossil Types Body fossils Trace fossils
- 8. Body Fossils Unaltered body fossils Altered body fossils
- 9. Trace Fossils Tracks, Trails, Burrows, Borings, Impressions, Molds, Casts
- 10. Body Fossils Any part of the actual animal or plant (bones, teeth, shells, and leaves). Only the hard skeleton is preserved (shell or bone), and the soft tissue (skin, muscle, organs, etc.) rots away after death. Unaltered Body Fossils No change in composition Altered Body Fossils Complete change in composition Trace Fossils Geological records of biological activity of organisms preserved on a substrate (e.g. burrows, borings footprints, muscle scars, feeding marks, and root cavities).
- 11. BODY FOSSILS Body fossil of a flat fish TRACE FOSSILS Chirotherium footprints in a Triassic sandstone
- 12. TYPES OF FOSSILIZATION (Mode of preservation) Body Fossils 1. Unaltered 2. Altered Trace Fossils
- 13. Fossilization in unaltered body fossils 1. Original skeletal material 2. Encrustations 3. Tar impregnation (Rancho La Brea tar pit in California) 4. Amber entombment 5. Refrigeration 6. Mummification
- 14. Fossilization in altered body fossils Petrification Permineralization Recrystallization Carbonization Replacement
- 15. Fossilization in trace fossils: • Mold i. External mold (impressions, tracks). – ii. Internal mold or steinkerns (invertebrate shells). • Cast • Compression • Borings / burrows • Coprolite • Gastrolith • Gnawing
- 16. Other types • Pseudo fossils • Index fossils • Living fossils • Sub fossils
- 17. Index fossils Define and identify geologic periods. Pseudofossils Inorganic objects, markings, or impressions that might be mistaken for fossils. Manganese dendrites on a limestone bedding plane.
- 18. Living fossil Any living species which resembles species that is only known from fossils and which has no close living relatives. Subfossil Remains, whose fossilization process is not complete, A subfossil skeleton
- 19. Uses of fossils • Prehistoric man utilized fossils in an attempt to ward off evil spirits. • Men of certain primitive culture use fossil bones as medicine, believing that they have mysterious power of healing wounds. • The scientists, however, use fossils to recreate the geological history of earth. • The tracing of the development of plants and animals.
- 20. • Climatic indicators. • Evidence of changing geographic patterns. • Economic tools. • Record of prehistoric life. • Evidence of organic evolution. • Stratigraphic indicator. • Cultural values.
- 21. Harsh weather. Impossible access to some dangerous areas. Nature of the metabolism of Achaean organisms. The early evolution of insects and microorganisms.