fossil evidence of evolution
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Fossil Evidence of Evolution. The Fossil Record. The Fossil Record – made up of all the fossils ever discovered on Earth provides evidence that species have changed over time Fossil – the remains or evidence of once-living organisms. Fossil Formation. Mineralization - PowerPoint PPT PresentationTRANSCRIPT
FOSSIL EVIDENCE OF EVOLUTION
The Fossil Record The Fossil Record – made up of all
the fossils ever discovered on Earth provides evidence that species have
changed over time
Fossil – the remains or evidence of once-living organisms
Fossil Formation Mineralization
minerals in water replace the organism’s original material and harden into rock
Carbonization extreme pressure
drives off the organism’s liquids and gases leaving only the carbon outline
Fossil Formation Molds and Casts
Mold – impression of an organism in hardened mud or sand
Cast – a fossil copy of an organism in a rock created by sediment filling in the mold
Fossil Formation Trace Fossils
preserved evidence of the organism’s activity, like footprints
Original Material original tissues
of an organism, like insects in amber (tree sap)
Relative-Age vs. Absolute-Age
Relative-Age – scientists determine the relative order in which rock layers were deposited( Most Accurate when the rock layers are undisturbed.)
Absolute-Age (Radioactive Dating)– scientists use the ratio of unstable isotopes to stable isotopes to find the age of rocks; more precise ex. carbon-14 dating
The Geologic Time Scale a chart that divides Earth’s history
into different time units
Extinctions Extinction – occurs when last
individual organism of a species dies Mass Extinction
when many species become extinct within a few million years or less
there have been 5 mass extinctions in the Phanerozoic eon
Causes of Extinction Sudden change – like meteor impact or
volcanic eruption Gradual change – like tectonic plates or sea
level changes
Biological Evolution the change over time in populations
of related organisms