oh boy, i did a lot of wikipedia bingeing to learn about geological timescales for this comic (and the next few), but here are the cliff’s notes:

the history of the earth is divided into 4 ‘eons’, the current one is called the ‘phanerozoic’, and it’s been going for the last 300 million years. basically everything interesting to do with evolution happens here.

the phanerozoic is divided into 3 ‘eras’:
the ‘paleozoic’ (boring single-celled organisms -> cambrian explosion -> much more fun organisms, yay!)
the ‘mesozoic’ (dinosaurs, yay!)
the ‘cenozoic’ (no more dinosaurs, boo!)

each era can be divided into ‘periods’ (we’re currently in the quaternary), and each period can be divided into ‘epochs’ (we’re in the holocene) if you wanna get real fancy. so it goes eon->era->period->epoch. remember that kids, you’ll be tested on it later (maybe).