Euthyphro dilemma asked for evolution.

[Angrboda]

Well, first off, evolution doesn't create anything, as it is not an agent. Evolution is a process, a process which, in our carbon based life forms we associate with certain more specific processes.

Evolution, in animals, can result in the probability of certain behaviors being more common than chance. This is just a stochastic process that, by nature of the behavior, modifies processes such that the creation of more animals displaying that behavior is more probable than not. A very basic behavior is sex. Any sexually dimorphic animal that doesn't engage in sexual behaviors will not create more of its kind, and that form will disappear. A form that is especially good at securing and mating with others will create more like itself that are good at reproduction, edging out less successful reproducers. Some behaviors are hard to analyze, like the wearing of funny hats. To quote Dan Barker, "morality is a function that a healthy brain performs." For reasons analogous to sex, animals that engage in moral behaviors which lead to their success in the species will result in more specimens displaying that behavior. Apparently, for our species, the behaviors we associate as moral behaviors, from thinking about moral cases to believing in the illusion that morality is objective, lead to more humans displaying same or similar moral behaviors. Note that this is likely species centric, and a dolphin, even if not cognizing its behaviors as moral, has behaviors, likely emotion based, which serve the same instrumental purpose in Dolphins.

Your notion that there is such a thing as morality independent of the open-ended self-modifying process that is evolution is an interesting notion, but before you introduce it as a key premise in your argument, you might actually demonstrate that it in fact exists.