EARTH HAS A LONG
HISTORY- MORE THAN
4 THOUSAND MILLION
YEARS.
Has this ever
happened before?
YES, IT HAS
HAPPENED BEFORE;
MORE THAN ONCE.
BUT THINGS
GOT INTERESTING WHEN
THE FIRST ANIMAL APPEARED
ABOUT 600 MILLION
YEARS AGO.
THEN, THERE WAS A
DRAMATIC CHANGE IN EARTH’S
CLIMATE, AND ALMOST ALL THE
PLANT AND ANIMAL SPECIES IN THE
WORLD DISAPPEARED. SCIENTISTS
CALL THIS A MASS EXTINCTION.
REALLY! AND HOW D0
WE KNOW IT HAPPENED?
Sep 2018
39