Evolution: A Remodeling process Section 15.2. Refinement of Existing Adaptations Any living organism may have many adaptations. A complex structure may.
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Evolution: A Remodeling
processSection 15.2
Refinement of Existing Adaptations
Any living organism may have many adaptations.
A complex structure may have evolved from simpler structures.
Ex: Camera –like eye of mammals has evolved from simpler eye types
Adaptation of Existing Structures to New Functions
Flippers of Penguins modified wings
Development Feet in various salamanders Salamanders vertebrates closely related
to frogs, live in land or water, but some live in trees
Tree dwelling ones have feet adapted to climbing
Ground Dwelling Tree Dwelling w/ more webbing
Fossil records
Section 15.3
Formation of FossilsFossil Records and the Geologic Time Scale
Dating FossilsContinental DriftMass Extinction
Fossil Records and the Geologic Time Scale
Most Recent Layers: Top Oldest Layers: Bottom
Geologic Time Scale
Distinct Ages in Earth’s HistoryPrecambrianPaleozoicMesozoicCenozoic
See fig 15-18 p337
Dating Fossils
Relative DatingAbsolute DatingRadioactive Dating
Relative Dating
Determines the Order in which events occurred
Not Actual Age
Absolute Dating
Determines how long ago an event occurred: Actual Age
Radioactive Dating
Based on measurement of certain radioactive isotopes.
Used to determine the absolute ages of rocks and fossils
Measured in Half-Life
Half-LifeTime required for a
radioisotope to lose ½ of its radioactivity.
Ex: Carbon-14: ½ life ~ 5730 yrs. decays into Nitrogen-14
Carbon-14 is produced in the atmosphere fairly constant rate
14C is constant in all living things. When an organism dies, it no longer picks up 14C.
By comparing the activity of a sample with the activity of living tissue time an organism has been dead
Continental Drift
Land masses on different plates change positions as a result of movement
Mass Extinction
Long periods of relative stability broken by comparatively brief episodes of species loss
5 or 6 over the last million years
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