Dragonflies were some of the first winged insects to evolve around 300 million years ago.
There are fossilized impressions of early dragonflies with a wingspan of up to two feet.
There large size was hypothesized to be due to high oxygen levels during the Paleozoic era.
Dragonflies are the best hunters with a 97% success rate. For comparison, lions are successful hunters about 20% of the time.