If new species arise very rapidly in small, peripherally isolated local populations, then the great expectation of insensibly graded fossil sequences is a chimera. A new species does not evolve in the area of its ancestors; it does not arise from the slow transformation of all its forbears.

'Punctuated Equilibria: An Alternative to Phyletic Gradualism', in Thomas J. M. Schopf (ed.), Models in Paleobiology (1972)