Fossil gaps, ghost lineages, and 'major extinction events'

The diversity of life we observe today is the product of deep-time diversification and extinction dynamics unfolding over hundreds of millions of years. Modeling these dynamics requires both phylogenies and fossil data, yet fossils are notoriously uneven in their temporal and taxonomic distribution. In their recent analysis of Hymenoptera, one of the great insect radiations, Jouault et al.¹ employed Bayesian Brownian Bridge (BBB) and PyRate² to estimate origination and extinction patterns. PyRate models diversification rates directly from fossil occurrence data, and the PyRate results appear to be dominated by gaps in the fossil record (Figure 1), suggesting that the inferred extinction events likely reflect overfitting to a sparse fossil record rather than robust signal of extinction.