Insect Fossils

Of all the animals on Earth, insects are overwhelmingly the largest class alive today, representing over 90% of the animal kingdom. Insects (meaning “sectioned body”) are united by a chitinous exoskeleton, a pair of antennae, compound eyes, a body segmented into three parts (abdomen, thorax, and head), and three pairs of jointed legs. Some insects may even possess one to two pairs of wings, though some prehistoric species also possessed a smaller third pair. Insect development and growth occurs either by molting (hemimetabolism), or through larval stages (holometabolism). The oldest insect fossil known is a Devonian-age 396 million year old silverfish-like creature called Rhyniognatha hirsti, of the Rhynie Chert in Scotland. Perhaps the most notable time in the prehistory of insects (and other arthropods) was during the Carboniferous period, where the heavily forested and oxygen-rich earth allowed them to grow to enormous sizes, such as the dragonfly-like Meganeura monyi, which possessed a wingspan of over 2 ft. long! Today’s insects have evolved into an almost limitless number of different species (approximately 1.4-1.8 million), with beetles alone making up 30% of the known animal kingdom (approximately 350,000-400,000 species).