there is no spoon said:
Scientific theory or is defined as "A hypothesis that has been substantiated either by observation, or a repeatable test." The wording my change from one text book/website to another but is says roughly the same thing. Now having said that, we can't test evolution in complicated organisms such as modern mammals, reptiles, birds..etc
You forgot one major point. The peer review process. The evolutionary theory has been through this process. It is accepted, it is considered scientific "law". Until something can come up and disprove it (which at this point, with the evidence evolution has, is improbable)
And you are wrong on one other point, and this shows where your research is not up to snuff. We HAVE witnessed evolution in complex organisms. http://www.sciencedaily.com/releases/2008/04/080417112433.htm
You consider reptiles to be "complicated" enough, that seeing this evolution should be enough to counter your argument that we havent "seen" evolution in a complicated organism. It can take decades to centuries for evolution to be witnessed, and quite frankly, we have only been trying to "witness" evolution for 40-50 years. And we have seen it already, in an organism that just produces more generations than others.
It could take thousands of more years for us to witness evolution in most mammals, besides domesticated animals which is just forced evolution. But that doesn't mean evolution is not real, or not happening.
Note: When I say fact in a scientific sense, I mean scientific law. Evolution is a scientific fact, it is a theory that has undergone the peer review process, has a mountain of evidence for and none against (except religious). It is the best possible explanation of the evidence that has been brought forth.