Studying Fossil Evidence Chapter 17 The Fossil Record

Studying Fossil Evidence Chapter 17

The Fossil Record ü The fossil record provides evidence about the history of life on Earth. It also shows how different groups of organisms, including species, have changed over time (or evolved).

Dating Fossils ü Relative Dating ü Method of determining the age of a fossil by comparing its placement with that of fossils in other layers of rock. ü Radioactive Dating ü Method of calculating the age of a fossil based on the amount of remining radioactive isotopes it contains

Biological Diversity ü Biological Diversity (Biodiversity) ü The variety of living organisms found in a particular place ü The fossil record tells us what kind of biological diversity existed in a particular place at a particular time in history.

Mass Extinction ü Event in which many types of living things become extinct at the same time. ü We know of Mass Extinctions because of the fossil record.

Mass Extinction ü Mass Extinction means that MOST, but NOT ALL species went extinct during a short time period. ü Because of GREAT BIOLOGICAL DIVERSITY before a catastrophic event, some individuals of some species survive the event.

Mass Extinction ü Adaptive Radiation: When many species disappear, habitats and ecological opportunities are left open for survivors take over ü The result seems to be a burst of evolution that produces many new species ü For example, when the dinosaurs went extinct, that cleared the way for evolution of modern mammals and birds

The fossil record shows speciation ü By studying the fossil record, we can see how species change over time.

Tempo of Speciation ü Gradual Speciation ü Slow, steady change over time ü Punctuated Equilibrium ü Long stable periods interrupted by brief periods of rapid change.

Numbers of Species Which groups demonstrated the greatest biodiversity during the Cenozoic Period?

In Review: ü The Fossil Record shows us Biodiversity, Mass Extinctions, Speciation and Evolution ü Fossil Dating ü Relative Dating ü Radioactive Dating

In Review: ü Biological Diversity (Biodiversity) ü The number of species that exist ü Mass Extinctions ü Most species die off ü Those species left living, evolve into new species by taking over the habitats and ecological opportunities left by those that went extinct = EVOLUTION ü Tempo of Speciation ü Gradual Speciation ü Punctuated Equilibrium