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Understanding historical patterns of diversity dynamics is of paramount importance for many evolutionary questions. The fossil record has long been the only source of information on patterns of diversification, but the molecular record, derived from timecalibrated phylogenies, is becoming an important additional resource. Both fossil and molecular approaches have shortcomings and biases. These have been well studied for fossil data but much less so for molecular data and empirical comparisons between approaches are lacking. Here, we compare the patterns of diversification derived from fossil and molecular data in scleractinian reef coral species. We also assess the robustness of molecular diversification rates to poor taxon sampling. We find that the temporal pattern of molecular diversification rates is robust to incomplete sampling when rates are calculated per interval. The major obstacle of molecular methods is that rate estimates are distorted because diversification rates can never be negative, whereas the fossil record suffers from incomplete preservation and inconsistent taxonomy. Nevertheless, the molecular pattern of diversification is comparable to the pattern we observe in the fossil record, with the timing of major diversification pulses coinciding in each dataset. For example, both agree that the end-Triassic coral extinction was a catastrophic bottleneck in scleractinian evolution. K E Y W O R D S : Diversification, extinction, fossils, molecular phylogenies, reef corals, speciation.Although historical patterns of diversity dynamics are most commonly inferred from the fossil record, it is possible to infer at least diversification rate from the molecular record using timecalibrated molecular phylogenies. If the patterns of diversification estimated with molecular methods can be trusted, then macroevolutionary questions can be asked in groups with poor fossil records and, perhaps more usefully, diversification rates can be inferred independent from potential biases in the fossil record. But how reliable are molecularly derived estimates of diversification dynamics and how do they compare to estimates derived from the fossil record? Both of these questions have received little empirical investigation.Even though the methods for estimating diversification rates from fossils or molecules are quite similar (Alroy 2009), there is a drastic difference in analytical protocols. In paleobiology, we accept that taxonomic turnover rates in fact vary substantially over time. The major goal of paleobiological research into taxonomic rates has been to develop methods for quantifying the historical pattern rates while minimizing bias (Foote

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