Not necessarily. For example, the KBS tuff was "securely dated" by Potassium-Argon (K-Ar), Fission Tracks, and Paleomagnetism at 2.6 million years, matching the expected age for the Australopithecines and other vertebrate fossils in the East African deposit; but with the discovery of Skull 1470, which most anthropologists considered much too modern to be almost 3 million years old, there was some controversy, and the K-Ar methods were re-explored until a date of 1.8 million years was obtained by some researchers. The Paleomagnetic and Fission Track dates were soon adjusted accordingly, until the new date was considered "remarkably concordant". In this and many other examples, the criterion for acceptance of the radiometric dates depended upon the fossils, or rather the evolutionary timeframe established for the fossils, which does not necessarily measure actual time.
2010 Arthur V. Chadwick, Ph.D.