ABSTRACT
Ever since the days of Charles Darwin, palaeontologists have been concerned about the quality of the fossil record. New concerns have arisen from two themes: (1) the finding that molecular dates of origin of certain major clades are often twice as old as the oldest fossils, and (2) the discovery that much of the variation in diversity, origination, and extinction signals from the fossil record can be explained by sampling. The molecular age-doubling phenomenon may be real, or it could be explained by either major gaps in the fossil record or by the inability of molecular techniques to discount unequivocally the possibility of rapid clock rates during times of divergence. The rock record certainly controls much of the fine detail of diversity and extinction plots, but mass extinctions, and the overall rise in diversity through time, may be real. Comparison of molecular and morphological phylogenies with the order and spacing of events in the rock record shows congruence, and hence suggests that much of the biotic signal in the fossil record is not misleading.
