With the arrival of the Carboniferous Period, forests of giant trees with heights of up to 40 meters, such as the Lepidodendron and Calamitales, spread out along wateredges. However, these trees were entirely unlike the "trees" we see today, and they became virtually extinct by the beginning of the Mesozoic Era. The plants that can be seen today, such as Lycopodium, Quillwort, and Horsetail are considered to be the closest surviving group to these giant Paleozoic trees.