Large areas of the continents covered by shallow seas. Climate generally warm and stable with little seasonal or latitudinal variation. Shallow seas expanding. Extensive deserts exist in continental interiors. Shallow seas limited in distribution.
Reptiles become more diverse.
Climate cold at beginning of the Permian then warms. Average elevation of landmasses at their highest shallow seas less extensive. First reptiles appear. Winged insects evolve. Occasional glaciation in Southern Hemisphere.