Insect Evolution: A Short Natural History

Insects show up in the fossil record in the Devonian, on the order of 400 million years ago. Rhyniognatha, from the Rhynie chert in Scotland, is one of the names people meet first. Treat it as an early landmark, and remember that specialists still argue about how to place the oldest fragments. I am not going to flatten that argument into a single “first insect” headline.

Wings and the giant years

Wings are the change that let insects occupy the air. By the late Carboniferous, some relatives were enormous by modern standards. Meganeura, a griffinfly, is the usual example: a wingspan on the order of 65 centimetres in the popular accounts. Arthropleura was a giant millipede-like arthropod from the same broad era, not an insect, and it shows up again as a prehistoric pack creature in the Roblox game. The animal and the game insect share a name and not much else.

Higher late-Paleozoic oxygen is one explanation for the size of giant flying insects. Clapham and Karr (2012) analyzed more than 10,500 fossil wing lengths and found that oxygen tracked maximum size early in their history, while later changes coincided with the spread of birds. Oxygen alone does not explain the full record: predation and competition also matter.

Social life comes later

Ants, bees, and termites are a much later chapter. Social colonies are not the start of the insect story. If you arrived here from a chart, a tree, or a timeline query, you want a museum or Wikipedia page next, not a tier list. The name guide is the fork in the road.