Summary | History Of Life On Earth | Siyavula

Summary

10.7 Summary (ESGCZ)

  • Scientists use deductive reasoning to understand fossils and the history of life on Earth.
  • Geological events often caused changes in climate, which in turn influence the emergence and disappearance of species.
  • It takes special circumstances for fossils to form, and fossils can be dated by radiometric or relative dating.
  • Climate and geography helped shape the evolution of life on Earth.
  • Geological timescales are divided into eons, eras and periods.
  • The Cambrian explosion was a rapid explosion in the diversity of life-forms. All animal groups have their origin in the Cambrian explosion.
  • During the Paleozoic the first fish, animals with shells and insects evolved and plants first colonised land.
  • The Mesozoic was the `age of dinosaurs', later in the era birds evolved, and gymnosperms evolved.
  • The Cenozoic is the most recent era and was the `age of mammals'.
  • Mass extinctions are massive losses in life, and there have been five mass extinction events in history.
  • In the last 4 million years significant changes have occurred in species occurring in Africa, including the evolution of humans.
  • Humans have a massive effect on biodiversity and the natural environment and are partially responsible for the '6th mass extinction'.
  • South Africa is rich in many fossils from diverse time periods.
  • Fossil tourism is a source of income and employment in fossil localities.