Actually, soil tests have shown that nuclear explosion has occurred on earth many civilizations ago. Perhaps the lizards became exposed to the radiation and "Honey, I blew up the Geckos!" happened. It caused the small creatures to become enlarged and malformed.
Eventually they were eaten by the giants that were in the earth "in those days." The flood really didn't happen. Noah did build a boat, but he sailed away to get away from the giants.
Scientists today have proven that feathers evolved from the scales of these prehistoric reptiles. So go figure.
This god just keeps playing games with genetics and destruction.
Oh and by the way, the giants are returning, They have been living underground all this time. The blood banks keep them feed and every now and then they grab a lost pet.