PRIMARY ERA

PRIMARY ERA
from 500 million to 250 million years ago
(or Paleozoic Era)

WITH THE END OF THE RAINS
A single large landmass emerged: PANGAEA,
surrounded by a single large ocean: PANTHALASSA.

Life forms adapted to the new changes.

500 million years ago
Animals with a skeleton appeared: vertebrates.

400 million years ago
Algae adapted to live on land.

350 million years ago
Some fish learned to breathe on land; fins transformed into legs: amphibians.

325 million years ago
Some amphibians stayed on land, developed scales, and evolved into reptiles.

300 million years ago
Plants developed leaves and stems: ferns.

ARCHAIC
PRIMARY
SECONDARY