The ancestors of modern dragonflies flew above the Earth long before dinosaurs walked upon it. The Protodonata were among the 1st winged insects on Earth. Fossils of these early dragonflies are over 300 million years old. In the Carboniferous Period, the time in Earth’s history from 360 – 290 million years ago, ancient dragonflies shared the land with early amphibians and the first reptiles. The forests were dominated by plants related to modern day horsetails and club mosses. Today’s trees and flowering plants had yet to evolve and the first dinosaurs would not appear for another 100 million years.

Carboniferous Period forest (from a display at the Chicago Field Museum).

By the Permian Period (290 – 248 million years ago), modern looking dragonflies had evolved. The earliest fossils thought to be true dragonflies date to 250 million years ago.

Dragonfly ancestors, the Protodonata, were the largest insects ever to fly on Earth. Some had wingspans of 75 cm! Large insects and other large invertebrates (including 1 m long scorpions!) may have evolved during the Carboniferous because oxygen levels in the atmosphere were much higher, 35% of the atmosphere instead of today’s 21%. Insects use thin tubes called trachea to get oxygen directly to their body cells. It’s thought that higher oxygen levels allowed oxygen to diffuse further in trachea and allowed larger insects to evolve.

Giant dragonfly ancestors flew in the Carboniferous Period, the time when our modern, carbon-based fossil-fuels (coal, oil and natural gas) were formed. Large, swamp-like forests covered much of the land. The poorly decayed remains of these forests became coal deposits. Marine planktons that sank to the sea floors and built up over eons became natural gas and oil deposits.

The hard exoskeleton of dragonflies and other insects can fossilize just like the bones of larger animals. In order to become a fossil an insect must die and come to rest where it is protected from scavengers and decay for a long time. This usually means sinking to the bottom of a pond or lake and being buried quickly under sediments. The insect’s actual remains must be preserved for many thousands of years before it can become a fossil. As more sediments pile up the remains are compressed and minerals replace the chitin and proteins of the insect body. Sometimes it is just an impression or mould of the insect in mud that becomes a fossil. Like many other insects, dragonflies have been fossilized in amber, too.

1) Basic Biology

2) Life Cycle

3) Palaeobiology

4) Biodiversity

5) Biogeography

6) Overwintering / Migration

7) Food

8) Sight and Flight

9) Cultural Significance

10) Conservation

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