7.2
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7.2. Evidence for Evolution. Fossil Evidence Texas fossils proved it was once covered by sea Kinds of Fossils Fossil – any evidence of life from an earlier geological time. Imprint of a leaf, feather, or organism in rock - PowerPoint PPT PresentationTRANSCRIPT
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7.2Evidence for Evolution
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I. Fossil EvidenceA. Texas fossils proved it was once
covered by seaB. Kinds of Fossils
a. Fossil – any evidence of life from an earlier geological time
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b. Imprint of a leaf, feather, or organism in rock
c. Cast made of minerals that fills in the follows of an animal track, mollusk shell, or other parts of an organism
d. A piece of wood or bond replaced by minerals
e. An organism frozen in icef. An insect or other organism trapped
in amberg. Sedimentary Rock – a rock type
formed from particles of preexisting rocks
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II. The Fossil RecordA. Scientists developed a geologic Time
ScaleB. Relative Dating
a. Estimate of how old a fossil isb. Based on the idea that the lower it is,
the older it will be.C. Radiometric Dating
a. Radioactive elements – give off radiation due to an unstable nucleus
b. Compares radioactive to non radioactive material to determine dating
c. Several samples to obtain consistent results
d. Uranium
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D. Fossils Show Evolution Occurreda. Simple life forms from past times
I. Other Evidence for EvolutionA. Homologous – body parts that are
similar in origin and structureB. Homologous structures indicate that
two or more species might share a common ancestor
a. Dolphin flipper and bird wing
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C. Vestigial Structuresa. Vestigial structure – a body part that
doesn’t seem to have a functionb. Whales and snakes with hip bones
D. Embryologya. Embryology – study of the
development in organismsb. Gills in all mammals
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A. DNAa. Closely related organisms have
similar DNAb. Bears and Dogsc. All primates have a common ancestor
i. Share hemoglobin, a protein in red blood cells that carries oxygen