The earliest land plants are represented by leafless, vascular plants called psilophytes. Europe and North America merge, forming the northern part of the ancestral Appalachian mountain range. Europe and North America straddle the equator. Africa and South America are positioned over the South Pole. The climate is generally warm and moist.
Ammonites evolve from nautiloids and become one of the dominant invertebrate forms.
Plant life, including lowland forests of giant psilophyta plants, develop and spread over the planet. Collisions between Laurasia and Gondwana form major mountain ranges. Coal-forming sediments are laid down in vast swamps. Global climatic changes occur, changing from warm and wet to cooler and drier. The result is a long interval of glaciation.