Geological Timeline
The timeline was developed as part of the American Museum of Natural History's "Reading the Rocks" web site. Consulting with museum scientists, I researched and painted the timeline images.

Proterozoic Period
Microscopic organisms begin in the seas. Primitive algae develops photosynthesis and gradually changes the chemistry of the Earths' atmosphere increasing its oxygen content.

Ordovician Period
New forms of life in the sea learned how to build a protective shell and and flourished. They formed abundant fossils such as trilobites. First fish and land plants appear.

Devonian Period
A small group of fish in the Devonian Period may have learned to live out of water by adapting to a life in dry mud as the early oceans recede.

Carboniferous Period
Amphibians adapted to live and feed on land but had to return to the water to breed. Coal swamps form and plants increase in size and complexity.

Permian Period
The evolution of the egg with its own food supply allows the reptiles to rule the land and the sea. Pangea forms and some life forms become extinct.

Jurassic Period
The super continent Pangea begins to break up and the Mediterranean Sea begins to form. Tropical plants are diverse and plentiful providing enough food for the very large and very hungry dinosaurs.

Credits:
Illustration: Kathy Konkle
Geologist: Ro Kinzler
Producer: Steve Gano
Client: The American Museum of Natural History