Carboniferous [kɑːbəˈnɪfərəs] (jan 1, 29800000 BC – jan 1, 2510000 BC)

Description:

First primitive reptiles. First winged insects. Spore-bearing plants dominant. First conifers. The rocks that were formed or deposited during the period constitute the Carboniferous System. The name Carboniferous refers to coal-bearing strata that characterize the upper portion of the series throughout the world.
Most notably, reef-forming organisms, such as tabulate corals and stromatoporoids (large colonial marine organisms similar to hydrozoans), were limited. Consequently, Carboniferous reefs were poorly developed because of this lack of framework builders. Benthic, or sea-bottom, marine communities were dominated by the crinoids, a group of stalked echinoderms (invertebrates characterized by a hard, spiny covering or skin) that still lives today. These animals were solitary suspension feeders that grew in such great profusion that they affected bottom currents and water circulation. The calcareous (containing calcium carbonate) remains of these organisms are significant rock-forming materials.