Data from: Boom and bust: ancient and recent diversification in bichirs (Polypteridae: Actinopterygii), a relictual lineage of ray-finned fishes

Understanding the history that underlies patterns of species richness
across the Tree of Life requires an investigation of the mechanisms that
not only generate young species-rich clades, but also those that maintain
species-poor lineages over long stretches of evolutionary time. However,
diversification dynamics that underlie ancient species-poor lineages are
often hidden due to a lack of fossil evidence. Using information from the
fossil record and time calibrated molecular phylogenies, we investigate
the history of lineage diversification in Polypteridae, which is the
sister lineage of all other ray-finned fishes (Actinopterygii). Despite
originating at least 390 million years (Myr) ago, molecular timetrees
support a Neogene origin for the living polypterid species. Our analyses
demonstrate polypterids are exceptionally species depauperate with a stem
lineage duration that exceeds 380 million years (Ma) and is significantly
longer than the stem lineage durations observed in other ray-finned fish
lineages. Analyses of the fossil record show an early Late Cretaceous
(100.5–83.6 Ma) peak in polypterid genus richness, followed by 60 Ma of
low richness. The Neogene species radiation and evidence for
high-diversity intervals in the geological past suggest a “boom and bust”
pattern of diversification that contrasts with common perceptions of
relative evolutionary stasis in so-called “living fossils.”