@drakthug drew this handy simple dragon guide. Then biologist Drosophilamelanobastard decided to create a more scientifically rigorous trait based phylogeny (family tree) assigning character states as 0 if the critter has the same state as the universal common ancestor and 1 if they have a derived trait. For example the ancestor probably had no wings so anyone with wings gets a 1 for wings. They then generated a phylogeny by grouping the critters with the most shared derived traits:

Sources: @drakthug & Drosophilamelanobastard