Arthropleura, an enormous myriapod that lived some 326 million years ago (Carboniferous period), is estimated to have been 55 cm (1.8 feet) in width and up to 2.63 m (8.6 feet) in length, weighing 50 kg. The 326-million-year-old fossilized section of the giant millipede Arthropleura, found in a sandstone boulder in the north of England. Image credit: Neil Daves. The giant fossil of Arthropleura — just the third such fossil ever found —...