The giant dragonfly Meganeura monyi sits blissfully unaware on a branch, as the giant scorpion Pulmonoscorpius kirktonensis creeps ever so slowly towards it's victim. Fossils show the scorpion to be 70cm (2.3ft) long, and the dragonfly's wingspan surpassed 75cm (2.5ft)! The Carboniferous provided these prehistoric insects and arachnids with an atmosphere of increased oxygen levels, which many scientists believe led to the increased size of these critters.
Big fleas have little fleas,
Upon their backs to bite 'em,
And little fleas have lesser fleas,
and so, ad infinitum.
And the great fleas, themselves, in turn
Have greater fleas to go on;
While these again have greater still,
And greater still, and so on.