This is an example of how the study of prehistory is constantly changing. Sometimes, it is difficult to know whether something we believe to be right is actually the case. While we have theories, new information can always come to life, making us question our past assumptions.
In this case, there are several discoveries that could lead to the questioning of this conclusion. For example, the scientist could make a discovery of a turtle fossil much older than the late Triassic. The scientist could also make a discovery of a primitive turtle that had no teeth.