Mean atmospheric O2
Geologic Time Scale
A pair of synapsids from the genus Dimetrodon fight over territory in a scene that must have been repeated many times 280 million years ago. Their spectacular sails are backlit revealing the translucent skin supported by long neural spines, each one sprouting from an individual vertebra. These Dimetrodon are each about 11 feet long. In the foreground are ferns and on the horizon on the right are seed ferns of the genus Alethopteris.
Copyright © Walter B. Myers. All rights reserved.
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