By the way, thure, welcome to EvCforum.
For an example of ambiguity lets go to a recent article in National Geographic, titled Human Fossil Adds Fuel to Evolution Debate by Hillary Mayell, March 25, 2002, they were discussing the possible age of “Java Man”, originally thought to be million years old then his age was changed to 1.5 million years.
Let's put this in perspective.
When these sorts of findings are reported, nobody in science takes them as reporting certain truth. Such findings are always considered tentative, and subject to revision with better evidence that might be identified in the future.
There was a mathematician who used to say that he was 2 billion years old. His reasoning: "when I was young, the earth was 2 billion years old. Now it is 4 billion years old. So I must be 2 billion years old." Of course, he was making a joke. But scientific methods do change, and as our techniques improve we can refine and re-evaluate data.
The theory of evolution does not depend on the specifics of this data. The ToE is mainly based on what we see with known species, and what we know about the processes involved in biological reproduction. The fossil evidence is not an essential part of the evidence base for ToE, although it does add additional support.
Ambiguity and uncertainty is to be expected in fossil evidence. It isn't a problem for evolution.
Incidently, the theory of evolution is also revised, as new evidence becomes available. When Darwin first proposed his theory, he did not know about genetics. We know a great deal more than was known at Darwin's time, and that new knowledge has been incorporated into our current understanding of evolution. The new knowledge could have turned out to contradict the theory of evolution. However, it didn't. Instead, it provided strong confirmation.