ERAS

Pre-Cambrian, Pre-Cambrian
The longest era of four
Four billion years from the birth of Earth
When life wasn't very much more than
Blue-green algae, slimy and wet
And bacteria milling around, I bet
There weren't many laughs, in fact I'd say
I wouldn't want to live in Pre-Cambrian days
 
Palaeozoic, Palaeozoic
Second longest era of four
Over three hundred million years of life
Our Earth for the first time saw
Invertebrates living in sea then on land
Fish, ferns, insects, amphibians and
Conifers spreading their seeds around
Reptiles creeping along the ground
 
Mesozoic, Mesozoic
Third longest era of four
One hundred million years it lasted
This era opened the door
To tiny little mammals no bigger than a shrew
Great big dinosaurs, some of which flew
The very first flowers and right at the end
An asteroid fell to Earth and then…
 
Cenozoic, Cenozoic
Shortest era of all
Sixty five million years ago
We mammals survived that fall
When those poor old dinosaurs died
Nobody cared and nobody cried
Mammals moved in where those beasts had been
That brings us up to the present day scene
 
When those poor old dinosaurs died
Nobody cared and nobody cried
Mammals moved in where those beasts had been
That brings us up to the present day scene