The transitional or intermediate forms of life needed to accomplish the process of natural selection required, in Darwin's own words, the "accumulation of infinitesimally small inherited modifications, each profitable to the preserved being" (The Origin of the Species, 74). The fossil record did not, however, provide the empirical support that Darwin wished for. He attributed the paucity of evidence to the incompleteness of the fossil record, but hoped that later discoveries would vindicate his theory.

Unfortunately for Darwin, the fossil record did not provide the evidence to support his theory, which led Stephen Jay Gould to admit that "All paleontologists know that the fossil record contains precious little in the way of intermediate forms; transitions between major groups are characteristically abrupt. Gradualists usually extract themselves from this dilemma by invoking the extreme imperfection of the fossil record" (The Panda's Thumb, 189). Gradualism, while not supported by the fossil record, nevertheless remains the best explanation for the majority of evolutionists because they cannot think of a more plausible alternative. However, not entirely satisfied with the fossil record, Stephen Jay Gould and Niles Eldredge proposed a new theory for explaining both the fossil record and the present diversity of life called "punctuated equilibria/equilibrium." This theory provided these paleontologists with an explanation for the patterns found in the fossil record.

No wonder paleontologists shied away from evolution for so long. It never seemed to happen. Assiduous collecting up cliff faces yields zigzags, minor oscillations, and the very occasional slight accumulation of change -- over millions of years, at a rate too slow to account for all the prodigious change that has occurred in evolutionary history. When we do see the introduction of evolutionary novelty, it usually shows up with a bang.