Fossils of "Hylonomus" have been found in the remains of fossilized club moss stumps in Joggins Fossil Cliffs, Nova Scotia, Canada. The theory is that, after harsh weather, the club mosses would crash down. The stumps eventually hollow out. Small animals such as "Hylonomus", seeking shelter, might enter and become trapped, starving to death. 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.