(*)
meter thick deposits of crinoidal limestone can be found in one of this period's subsystems, which also saw a huge population of lycopods. Its Tournaisian stage is separated from its preceding period by the appearance of the conodont Siphonodella sulcata. Romer's Gap appears at the beginning of it, dividing a fossil record with many armored and lobe-finned fishes from one with ray-finned fishes roughly twenty million years later. The Uralian Orogeny began in this period that also saw the Alleghenian Orogeny form the Appalachian Mountains.(*) This period's best known feature was caused by the evolution of plants using lignin, which could not be digested by existing decomposers, and facilitated by this period's Rainforest Collapse, which included the death of its giant dragonflies. Gondwanaland and Laurasia formed in this period divided into the Mississippian and the Pennsylvanian periods. For 10 points, name this period known for the formation of coal beds.
meter thick deposits of crinoidal limestone can be found in one of this period's subsystems, which also saw a huge population of lycopods.
Carboniferous Period