The rising levels of oxygen during the late Paleozoic icehouse had major effects upon evolution of plants and animals. Higher oxygen concentration (and accompanying higher atmospheric pressure) enabled energetic metabolic processes which encouraged evolution of large land-dwelling arthropods and flight, with the dragonfly-like Meganeura, an aerial predator, with a wingspan of 60 to 75 cm. The herbivorous stocky-bodied and armoured millipede-like Arthropleura was long, and the semiterrestrial Hibbertopterid eurypterids were perhaps as large, and some scorpions reached .
