Dragonflies, from the order Odonata, have been around for over 250 million years. The most conspicuous difference in their evolution over time is the steady shrinking of their wingspan from well over two and a half feet down to a few inches. Voracious predators, today they dine on bees, wasps, butterflies and avoid the attentions of birds and wee lizards --  but back in the day, they had a much larger selection of meals within their grasp. Small lizards and birds who today choose dragonflies as a tasty snack used to be their preferred prey.