Coal forest

[1][2] As plant matter from these wetland forests decayed, enormous deposits of peat accumulated, which later became buried and converted into coal over the subsequent geologic eras.

This process may have greatly increased the atmospheric concentration of oxygen to possibly as high as about 35%, making the air more breathable by animals with inefficient respiratory systems, as indicated by the size of Meganeura compared to modern dragonflies.

[3] Coal forests covered tropical Laurasia (Europe, eastern North America, northwesternmost Africa) and Cathaysia (mainly China).

At the very end of the Carboniferous, the coal forests underwent a resurgence, expanding mainly in eastern Asia, notably China; they never recovered fully in Laurasia.

Lycopsid genera specialized in various roles: Paralycopodites as a pioneer on newly silted lakes shallow enough for land vegetation to start; Diaphorodendron later when the ground had become peaty.