PIX4632855: Arthropleura - An arthropleura crawls among ferns in a carboniferous forest 310 million years ago. The Arthropleura is considered to be the largest arthropod of all times measuring 2-3 metres in length. He is a distant relative of arthropods such as a thousand-legged. A four foot long Arthropleura crawls amidst seed ferns from the genus Neuropteris in a Carboniferous forest 310 million years ago in what is today Scotland. Growing up to 8 feet long and 18 inches wide, Arthropleura was the largest known terrestrial arthropod of all time. A combination of a higher percentage of atmospheric oxygen and relatively few terrestrial predators may have enabled Arthropleura to evolve to such an enormous size. Despite its fierce appearance, Arthropleura is currently believed to have been a vegetarian. In the shadows on the upper right are “” roachoids,””” primitive ancestors of modern cockroaches / Bridgeman Images