Arthropleura, the "Jointed Ribs," is an iconic Carboniferous arthropod that was popularized by the TV series 'Prehistoric Park.' This giant millipede could grow to over two meters long, taking it out of the "creepy crawly" range and upgrading it to "arthropod overlord." Although intimidating in size, this gentle giant was either an herbivore (an animal that eats plants) or a detritivore (an animal that eats dead organisms). Scientists know this because if Arthropleura was a carnivore, it would have hard mouth parts that would fossilize, but no mouth fossils have been found. Even though it didn't prey on other animals, Arthropleura wasn't defenseless; in addition to its tough exoskeleton, it may have secreted toxins just like its modern day relatives! Arthropleura thrived during the Carboniferous Period of North America and Scotland, scuttling along the floor of the lush rainforests that the period is known for. Arthropods were the dominant life forms in these forests, allowing animals like Arthropleura and Meganeura to grow to colossal sizes. Plants also reached new heights; the horsetail Calamites and the scale tree Lepidodendron each grew 30 meters tall! However, at the end of the Carboniferous all of these huge organisms perished as the life sustaining rainforests collapsed.