New leaps forward came.
They modified their scales.
Skin was invented.
They hunted their ancient rivals.
They looked back at their ancestors
Still confined to the oceans, lakes and rivers.
They found that they could never go back.
They had to push on as reptiles now
They needed to build a new empire of their own.
These new empire builders found a changed world.
There was one landmass
There was one ocean.
Reptiles now had the run of the land.
They played with their designs.
Some created great sails.
Others grew big,
Competed for dominance.
Then things changed.
A new schism happened.
Reptile split with mammal.
Then the die-off.
The sail-backed Pelycosaurs,
Along with the trilobites before
Live in mammalian museums now
Locked in stone
As mementos of the past.