10.7 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.