Mean atmospheric O2
Geologic Time Scale
A pair of carnivorous synapsids from the genus Dimetrodon explore an Early Permian landscape 280 million years ago. The tree on the left is a gymnosperm of the genus Cordaites, an ancient ancestor of today's conifers, and on the far right is a seed fern of the genus Glossopteris, a plant that came to dominate this period with over 70 species.
Copyright © Walter B. Myers. All rights reserved.
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