Abstract
In this paper, I reconsider the theory of punctuated equilibria and argue that the essential idea of the theory originated from the biostratigraphic way of seeing the fossil record. It must be noted that biostratigraphers have recognized and exploited the longterm morphological stability following a geologically abrupt origin for a long time. I suggest that the empirical success of biostratigraphy supports the pattern hypothesis of punctuated equilibria. Reexamining the controversy over the theory of punctuated equilibria, I conclude that the theory was really important not because it changed the explanans (evolutionary mechanisms) but because it changed the explanandum (macroevolutionary patterns that need to be explained).
