....
HARD SHELLED CREATURES APPEAR:

The PHANEROZOIC EON began 570-million years ago and runs to present time.
  Below is a chart depicting the three basic divisions of this most recent Eon -- these divisions are called ERAS. 

mya = millions of years ago

...
At the onset of the Paleozoic Era (the earliest of the three eras listed above), creatures with hard shelled bodies now appear --
yet the process of evolution has been astoundingly slow --  the creation of hard shelled animals has taken 
nearly 3.2-billion years since life first appeared on Earth! 

( It took Eons to develop the Chicken we've come to know and love.  Soon we will learn just how resilient to crisis the mighty Chicken has been. )
...
Next,  we discover the Paleozoic,  the earliest Era,  and the most astonishing Era in the history of Earth.
The next episode is called, TheWorst Mass Extinction of Life on Earth