I consider that an excellent question since it was the one think that kept me from becoming a creationist. After some study I found out that the evidence was being forced to fit the theory. The theory, of course, should be conformed to the evidence.
Consider that there are about 6000 known fossil hominids (and I use the term loosely). Only about 1% of them are on display. Why? Because the others don't fit the theory? They are apparently normal looking fossils and don't do anything to promote the picture of gradual evolution.