Fossils Fossils Remains Imprints Traces or Evidence of

Fossils

Fossils: Remains, Imprints, Traces, or Evidence of Once Living Organisms. l l l 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. l l l 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 l l Like a picture of the organism. Thin layer of carbon often left behind forming image.

Mold and Cast l l 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 Fossil l Evidence of animal activity. – Examples: l l l Footprints Worm holes Burrows

Petrified Remains l l 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 l Actual parts of organism found – Examples: Insect in amber l Animal frozen l Animal trapped in tar l

Index Fossils l From species that – – – l 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.