Mean atmospheric O2
Geologic Time Scale
Dimetrodon grandis portrait
An eleven-foot-long synapsid from the species Dimetrodon grandis traverses an Earth that became cooler and drier during the Early Permian period 280 million years ago.
Long before the reign of dinosaurs Dimetrodon emerged as the dominant land predator, a position they held for the next 20 million years. Contrary to their reptilian stance and dinosaur-like appearance, Dimetrodon are in fact more closely related to mammals, and hence to humans, than to dinosaurs or reptiles.
Copyright © Walter B. Myers. All rights reserved.
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