359-299 million years ago

amphibian in forest

In the Carboniferous, mountain ranges such as the Applachians, Atlas, Alpines, and early Himalayas were forming. The climate was warm and by the end of the Carboniferous, most regions lacked seasons. The very dense forests and swamps in this time would form most of the coal deposits of the world as dead plant material accumulated in anoxic waters. The concentration of oxygen in the atmosphere rose to 30% because of the abundance of plant life. Insect herbivory became more widespread. The first gymnosperms evolved and lycopods dominated swamps.