Archaeothyris was an amniote which lived 320 million years ago, in the Middle Carboniferous period. It is the oldest undisputed synapsid known. It was found in Nova Scotia, the same locality as Hylonomus, and Petrolacosaurus, all of which resemble Archaeothyris.


See Special:Whatlinkshere/Etymology:Archaeothyris for a list of articles using this term.

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