Arthrosapiens

The Arthrosapiens are the collective name for intelligent, sapient insectoids and arachnids that have replaced humans as the dominant lifeform in their timeline. They are the product of speculative and ultimately convergent evolution.

History
In the timeline of the Arthrosapiens, the Carboniferous period – a period in Earth's history defined by expansive forests and an atmosphere much richer in oxygen compared to the present day – lasted much, much longer. The greater concentration of oxygen in the atmosphere enabled insects to grow to comparatively massive sizes, with dragonflies the size of eagles and millipedes the size of alligators. Naturally, this prolonged Carboniferous period resulted in said insects possessing larger bodies, and by extension, larger brains. Very, very gradually, developments in the brains of these super-sized insects enabled them to gain sentience, and even further down the line, sapience.

Their bodies began to change to accommodate their newfound intelligence: in a striking example of convergent evolution, insects began to stand upright on their hind legs, using abdomens to keep balance and enabling the legs to gradually be shaped into arms through continuous evolution.

Species
The Arthrosapiens are an extremely diverse collection of species, each one bearing resemblance to common insects and/or arachnids.