Fossils of the basal pelycosaur `` Archaeothyris '' and the basal diapsid `` Petrolacosaurus '' are also found in the same region of Nova Scotia , although from a higher stratum , dated approximately 6 million years later .
Fossils of the basal pelycosaur `` Archaeothyris '' and the basal diapsid `` Petrolacosaurus '' are also found in the same region of Nova Scotia , higher up , dated about 6 million years later .