Sphagnum ones ("Rigida" and "Squarrosa") has been clarified using molecular phylogenetics. All but two species normally identified as "Sphagnum" reside in one clade; two other species have recently been separated into new families within the Sphagnales reflecting an ancestral relationship with the Tasmanian endemic "Ambuchanania" and long phylogenetic distance to the rest of "Sphagnum". Within main clade of "Sphagnum", phylogenetic distance is relatively short, and molecular dating methods suggest nearly all current "Sphagnum" species are descended from a radiation that occurred just 14 million years ago. "Sphagnum" mosses occur mainly in the Northern Hemisphere in peat bogs, conifer forests, and moist
Moss Antarctica and Russia, and a case is put forwards for Carboniferous mosses. It has further been claimed that tube-like fossils from the Silurian are the macerated remains of moss calyptræ. Mosses also appear to evolve 2–3 times slower than ferns, gymnosperms and angiosperms. Recent research show that ancient moss could explain why the Ordovician ice ages occurred. When the ancestors of today's moss started to spread on land 470 million years ago, they absorbed CO from the atmosphere and extracted minerals by secreting organic acids that dissolved the rocks they were growing on. These chemically altered rocks in turn reacted