Everything was good on earth... It was going perfectly fine! People went to their jobs, kids went to school, adults payed their taxes, ect.. That was until- the breakout... Total extinction... But the animals weren't the ones going extinct.

As a matter of fact, there was a lab studying extinct animals, which ranged from dinosaurs, to early ages of mammals... THAT'S what broke out... Dangerous animals like T-rexes, Spinosaurouses, Titanoboas, smiledons, ect. Were EVERYWHERE... Causing the human population to decrease rapidly.

Now every part of the world was invaded by these extinct animals... Very few survivors...