Arthropleura was up to 2.6 meters ( 8.5 feet ) long relative of centipedes and millipedes from the Upper Carboniferous ( 340 to 280 million years ago ) of what is now North America and Scotland. It is the largest known land invertebrate of all time. recently discovered fossils have been found with pteridophyte spores in the gut and in associated coprolites suggesting that the creature ate plants.