Fossil Record

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Fossil Record
6.1 Fossils and Evolution

• Definition The fossil record is all the known
  fossils and their placements in the formation of
  rocks and positions in time.

• Information The fossil record is evidence of
  the evolution of plants and animals, and their
  extinction.

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Fossil record
6.1 Fossils and Evolution
(cont.)

• Why are there gaps in the fossil record?
• Decay before fossilization
• Geological process destroy fossils
• They are undiscovered

How can fossil and rock data determine when an
organism lived?
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Homologous Structures
6.2 Biological Evidence

• DEFINITION Parts of organisms that are similar
  in origin and structure are called homologous
  structures.

• INFORMATION
• Are the result of evolution
• Can indicate how closely two or more species
  share common ancestors

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Homologous Structures

• EXAMPLES At some point in our pasts, humans,
  frogs, bats, birds, and cats all shared a common
  ancestor, because the bones in the upper limbs
  are homologous.

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Homologous Structures (cont.)
6.2 Biological Evidence
The bones in the upper limbs of these animals are
homologous structures.
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Analogous Structures
6.2 Biological Evidence

• DEFINTION Analogous structures appear similar,
  but have different ancestral origins.

• INFORMATION Result from similar environmental
  conditions that produced similar natural
  selection outcomes
• EXAMPLE The wings of birds and insects.

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Vestigial Structures
6.2 Biological Evidence

• DEFINTION structures that have no function in
  their present-day form.

• INFORMATION Scientists hypothesize that the
  structures once functioned in an ancestor.

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Vestigial Structures

• EXAMPLES
• Pelvic bones in whales
• Wings in ostriches
• Pelvic spurs in boas and phythons
• Eyes in cavefish
• Tail bones in humans

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Embryology
6.2 Biological Evidence

• DEFINTION The science of the development of
  embryos from fertilization to birth is embryology.

• INFORMATION The more closely related species
  are, the more features they share during
  development.
• EXAMPLES Fish, reptiles, birds, and human
  embryos

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Geographic Isolation
6.3 Evolution and Plate Tectonics

• Definition Geographic isolation occurs when
  populations of species are separated by a
  physical barrier.

• Information Leads to closely related species
  that appear different.
• Examples
• Salamanders in California and Oregon
• Squirrels in the Grand Canyon

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Convergent Evolution
6.3 Evolution and Plate Tectonics

• Definition Convergent evolution results in
  structural and functional similarities.
• Information Sometimes distant locations with
  similar environmental conditions have species
  with similar traits that evolved independently.
• Examples Catci and Euphorbia