The plant life of the Carboniferous period was extensive and luxuriant, especially during the Pennsylvanian. It included ferns and fernlike trees; giant horsetails, called calamites; club mosses, or lycopods, such as Lepidodendron and Sigillaria; seed ferns; and cordaites, or primitive conifers. Land animals included primitive amphibians, reptiles (which first appeared in the Upper Carboniferous), spiders, millipedes, land snails, scorpions, enormous dragonflies, and more than 800 kinds of cockroaches. The inland waters were inhabited by fishes, clams, and various crustaceans; the oceans, by mollusks, crinoids, sea urchins, and one-celled foraminifera.
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