Presentation on theme: "Fossils The remains or evidence of a living thing."— Presentation transcript:
Fossils The remains or evidence of a living thing
Fossils: Remains, Imprints, Traces, or Evidence of Once Living Organisms. Tells us what, where, when, how organisms lived. Tells us the history of life on earth. Tells us about climates and environments of the past.
Conditions Necessary to Create Fossils. Organism quickly buried to avoid decay. Hard parts which are less likely to decay. Usually occur in Sedimentary rock.
Types of Fossils Carbonaceous Films Mold & Cast Trace Fossils Petrified Remains Original Remains
Carbonaceous Films Like a picture of the organism. Thin layer of carbon often left behind forming image.
Mold and Cast Buried hard parts in rock dissolve or decay leaving a MOLD (empty space in rock). Mold later fills with sediments that harden forming a CAST (filled in mold).
Trace Fossils Marks or evidence of animals but show no part of the animal Ex: footprints, droppings, burrows
Petrified Remains Hard and rock like Original material replaced by minerals Water flows through removing material and carrying minerals that crystallize in their place Most bones found are petrified.
Original Remains Actual parts of organism found – Examples: Insect in amber Animal frozen Animal trapped in tar
Preservation Freezing Amber: when sap fossilizes with trapped organisms Tar Pits: trap animals and preserve them
Fossil Interpretation Fossils are arranged according to age, so they show a progression of development Fossils indicate past surface conditions Fossils give evidence of past climates Fossils tell appearance and activity of plants and animals
Index Fossils From species that – Existed for a short period of time – Were abundant – Were wide spread Used to determine the age of rock layers that contain them. – Rock layers that contain the same index fossil are thought to be about the same age.