During this period, the Rheic Oceans disappeared, while the Hercynian and Appalachian Mountains formed as Laurussia and Godwanaland collided together. It saw the diversification of skates, rays, and other members of Elasmobranchii. Arthropleura and Meganeura, the largest documented invertebrate and flying insect, respectively, overcame traditional limitations on gigantism 
During this period, the Rheic Oceans disappeared, while the Hercynian and Appalachian Mountains formed as Laurussia and Godwanaland collided together. It saw the diversification of skates, rays, and other members of Elasmobranchii. Arthropleura and Meganeura, the largest documented invertebrate and flying insect, respectively, overcame traditional limitations on gigantism as atmospheric oxygen levels reached 35%. The Gzhelian Age at the end of this period featured a diversification of reptiles as sea levels receded, and tetrapods gained greater access to inland areas due to the development of the amniote egg. The development of lignin and the evolution, from cordaites, of conifers during this period contributed to its namesake fossils. For 10 points, name this geological period that follows the Devonian, whose name derives from the many coal beds that were laid down during it.
During this period, the Rheic Oceans disappeared, while the Hercynian and Appalachian Mountains formed as Laurussia and Godwanaland collided together.
Carboniferous period