Debunking evolution

In a number of threads I've been involved with, the validity of the theory of evolution has been questioned extensively. Some people have claimed that it can't work and there is no evidence to support it. Now, it's my understanding that scientific hypotheses and theories (for ease of typing and reading, I will refer to both under the heading of theory) aren't proved, but disproved. In other words, if evidence is found that disproves a theory, it is dropped or modified according to the new evidence.

My intention with this thread is to look at the evidence which would be able to disprove the theory of evolution. For example, the confirmed existence of a modern mammal among dinosaur fossils. Or an organism with DNA that does not match any other organism or, indeed, something other than DNA.

It has also been claimed that the discovery of a living dinosaur would debunk evolution. I'm not sure why this is thought to be so, because there are organisms that have remained essentially unchanged for millions of years. Consider the humble Lamprey; originated prior to dinosaurs and has remained essentially unchanged since. Rather than disproving evolution, this, in my opinion, goes to confirming it. If an organism is well adapted for its environment and that environment remains reasonably constant over time, the theory would predict little change in it.

Anyway, I'd be interested to see other's opinion and other evidence that, if it was found, would disprove evolution.