Creepy-crawly ancestors

We all squirm, scream and swat at the sight of insects, but have you ever asked yourself where they actually come from?

Insects were walking the Earth long before dinosaurs came into existence and the earliest insect fossil, Rhyniognatha, dates as far back as 400-million years ago, to the Devonian Period. It has been quite a challenge for palaeontologists to discover information about how insects evolved.

Although many insect specimens have been found trapped in amber, coal, volcanic ash and other substances, there is a lack of evidence on the evolution of insect flight, compound eyes and metamorphosis, for example.

Insects lack bones and with no fossilised insect skeletons left behind, palaeontologists have had to rely on amber, trace fossils and mineral replications.

Insects that roamed the earth millions of years ago were giants in comparison to modern-day creepy-crawlies.

Research has shown that as the oxygen concentration in the atmosphere decreased over geological time, insects also became smaller because of the limitations of their respiratory systems.

Check out these modern creepy-crawlies and their ancestors.

Protodonata, ancestors of the modern-day dragonfly, were among the first winged insects to exist. The Protodonata were the largest insects to ever fly on earth, with wingspans reaching up to 75cm in length! Today’s largest dragonflies only have a wingspan of about 16cm, which is tiny in comparison to their ancestors.

Many can’t help but stare (and squeal in fright!) at the sight of these multi-legged arthropods. Ancestors of the millipede and centipedes, Arthropleura, are said to have been around 2m in length. Centipedes and millipedes are considered some of the fastest arthropod runners, reaching speeds of about 40cm per second.

As creepy as they are, it’s worth remembering that insects are part of the earth’s evolutionary history – and they inhabited the Earth long before humans or dinosaurs.