Here is the full list of all 20 Prehistoric Tales achievements.
For winning 40 battles.
For using 70 spells in battles.
For eliminating 250 dinosaurs.
For using 30 spells in battles.
For winning 20 battles.
For rescuing the valley from the invasion of greenskins.
For winning 7 battles.
For building 40 constructions in your settlement.
For finding 25 artifacts and rare items.
For 200 exchanges with traders.
For reaching level 25.
For 70 exchanges with traders.
For finding 15 artifacts and rare items.
For making friends with a little greenskin.
For starting trade relationships with neighboring tribes.
For reaching level 15.
For building 15 constructions in your settlement.
For finding the arena of ancient battles.
For reaching level 10.
For collecting 120 plants.