An extra 125 million years would be more than enough time, they thought. These are dated at some 470 million years. But even though the first fish now appeared some 50 million years earlier, still there was plenty of time for evolution to have worked, they thought. By the late 1990s, fish had been found even 'earlier', from the Early Ordovician system, supposedly around 490 million years ago. Vertebrates had now been found at the base of the Cambrian along with all the other multi-celled animals.
Fossils are found where they are found - there is really no 'right' or 'wrong' place.
A scientist may have difficulty explaining some fossils by his notion of evolution and so he may be reluctant to accept the fossil as authentic. Indeed this may have been why for many years the fragments of early fish fossils were disputed. And the second lesson to learn is that belief in evolution is not upset by new fossil finds. Evolutionists do not question evolution because they already believe it as a fact. New fossil discoveries just make them change their stories.