Bio Wk 3 Extinction, past ecosystems

• • There have been many “ice ages” throughout the 4.5 billion-year history of Earth.
• The last ice age is the only one in which humans were present
• The average size of Australian animals has decreased significantly in the last 100 000 years
• There are two leading theories as to why this extinction occurred, changes in climate and the arrival of humans
• aboriginal art serves as a guide for scientists to see if what animals existed in the past