Earth Formed Scientists expect that the Earth was first created by rock,dust and ice .Then gravity pulled everything together .At first the Earth was too hot for water to stay on it .Then the Earth began to cool and it began rain to create the first oceans.Afterwards rocks began to form ,the oldest rock was found in Canada it was from 4,055 million years ago it is very rare that anyone find rocks from this long ago.Other ancient rocks have been found all over the world.
Cells And Organisms Began To Form A long time ago prokaryotic cells were the only thing that was alive on Earth prokaryotic cells were extremely simple cells .When they were first on earth they had no nucleas (brain).Next euryotic cells appeared the prokaryotic eventually turned into the euryotic cell .This helped the prokaryotic cell's chance at survival this has a nucleas (brain).Then jellyfish like animals formed or multicellular organisms .Jellyfish have been around for a long time .Jellyfish can survive in warm and cold water .There are lots of different kinds of jellyfish.Another multicellular organism is the ancient worm at first worms lived in the ocean .They're bodies are only some ancient worms have stomachs. Another life form from the precambrian time is the arthropod some examples are spiders,insects,crabs and lobsters.Except before they were worms beforehand.When arthropods were worms they had antennas on their heads, lots of legs and a tail.
First Mass Extinction The mass extinction ended the precambrian time James F. Miller thinks the mass extinction happened because the climate got colder because it was so different from the usual warm weather of the precambrian time.The ice covered the water causing low oxygen for the life underwater.
The Precambrian Era The time was called ''time of ancient life''.When life started to first form on Earth it was called the ''Cambrian Explosion'' . This was the era that life on earth first started .In fact some of the animals we see today were ancestors of the animals from this era.