The Cambrian explosion - the geologically abrupt appearance, roughly 540 million years ago, of most major animal body plans in the fossil record - has long been treated as biology's most conspicuous discontinuity. For much of the twentieth century, paleontologists read the pattern literally: a genuine burst of morphological innovation compressed into a few million years, unmatched before or since. Yet the inference from fossil pattern to evolutionary process is less secure than that reading assumes, and two distinct challenges have complicated it. The first challenge is taphonomic. Fossilization is a rare and biased event; soft-bodied organisms and microscopic larvae leave little trace, and the mineralized skeletons that dominate Cambrian deposits are precisely the structures most likely to be preserved. On this view, the 'explosion' records not the origin of animal lineages but the origin of hard parts - a threshold in preservability rather than in diversity. The lineages themselves, the argument runs, may have diverged tens of millions of years earlier, evolving quietly as small, unskeletonized forms invisible to conventional collecting. Molecular phylogenetics supplied the second challenge, and initially seemed to confirm the first. By calibrating the rate at which genetic sequences accumulate substitutions, early molecular clock studies pushed the divergence of major animal groups deep into the Precambrian, sometimes to a billion years ago - long before any Cambrian rock. Here, however, the author counsels caution. Molecular clocks are only as reliable as their calibration, and substitution rates are neither constant across lineages nor easily estimated when the fossil calibration points are themselves disputed. When later analyses relaxed the assumption of a uniform rate and incorporated more conservative calibrations, the molecular estimates contracted toward the paleontological ones, though a gap remains. What emerges is not a refutation of the explosion but a refinement of what it explains. Even granting an earlier, cryptic divergence of lineages, the Cambrian still marks a real and rapid elaboration of body plans - the assembly of complex morphologies, not merely the branching of genealogies. Divergence and morphological innovation are separable events, and conflating them has produced much of the controversy. A lineage may split long before it acquires the developmental architecture that makes it recognizable as an arthropod or a chordate. The most productive recent work therefore treats the explosion as a problem in developmental and ecological dynamics rather than a mere counting of first appearances. The elaboration of gene regulatory networks, the advent of predation, and rising oxygen levels have each been proposed as enabling conditions. None alone suffices, and the author declines to elevate any single factor to the status of cause. The lesson is methodological: the fossil record measures one thing, the molecular record another, and the developmental record a third. Progress has come not from choosing among them but from recognizing that each answers a different question. The apparent suddenness of the Cambrian, once an embarrassment to gradualist orthodoxy, now looks less like an anomaly to be explained away than a genuine phenomenon whose components must be disentangled before any of them can be explained.