The coelacanth is an example of what are known as Lazarus taxa: living things that are presumed long extinct until contrary evidence is discovered. Of course, predicting whether a single extinct species will one day be rediscovered living in some corner of the planet is nearly impossible. But if we look at large groups of species we sometimes can determine, in aggregate, how many species might actually not be extinct after all, and how often facts are incorrect and need to be overturned.Samuel Arbesman, The Half-Life of Facts: Why Everything We Know Has an Expiration Date (New York: Current, Penguin USA, 2012), ch. 3 (citing Diana O. Fisher & Simon P. Blomberg, "Correlates of Rediscovery and the Detectability of Extinction in Mammals," Proceedings of the Royal Society B: Biological Sciences (Sept. 29, 2010))
In 2010, two biologists at the University of Queensland . . . tabulated all the mammals that have very likely gone extinct in the past five hundred years. This yielded a list of 187 species. Then they checked to see how many were eventually recategorized as nonextinct. The answer: More than a third of all mammals that allegedly were lost to time in the past five hundred years have since been rediscovered.