Two pulses of morphological diversification in Pacific pelagic fishes following the Cretaceous–Palaeogene mass extinction

Molecular phylogenies suggest some major radiations of open-ocean fish clades occurred roughly coincident with the K/Pg boundary, however the timing and nature of this diversification is poorly constrained. Here we investigate evolutionary patterns in ray-finned fishes across the Cretaceous-Palaeogene (K/Pg) Mass Extinction 66 million years ago (Ma), using microfossils (isolated teeth) preserved in a South Pacific sediment core spanning 72-43 Ma. Our record does not show significant turnover of fish tooth morphotypes at the K/Pg boundary: only two of 48 Cretaceous tooth morphotypes disappear at the event in the South Pacific, a rate no different from background extinction. Capture-mark-recapture analysis finds two pulses of origination in fish tooth morphotypes following the mass extinction. The first pulse, at ~64 Ma, included short-lived teeth, as well as forms that contribute to an expansion into novel morphospace. A second pulse, centered at ~58 Ma, produced morphotype novelty in a ...