(Just some notes for me to take here on the evolution of species from Ashlar.)
Dwarves evolved from earlier, hairier humans. They adapted at mountain ranges and became short but bulky, a perfect body for climbing mountains and exploring caves. They also ended up having larger pupils, allowing them to see more in the dark caverns.
Elves evolved from later, less hairy humans. Eating and growing vegetables, along side small amounts of meat, they became very thin. Their ear shapes were also pointier so they would be able to hear animals better while hunting.
Trolls evolved from early elves. They adapted in mountain ranges, much like dwarves, making them more muscular.
Dragons were made from artificial selection by Silurians that managed to survive the meteorite and poisonous gasses released from it.. They were bred from pterodactyl-like species and tyrannosaurus rex-like species.