Rise of modern marine fishes captured in an early Paleocene Lagerstätte

The Cretaceous-Paleogene (K-Pg) extinction reshaped Earth's biodiversity, yet its impact on marine fishes remains debated due to gaps in the Paleocene record. Here, we report a paleotropical assemblage from the early Paleocene (Danian) of Egypt that provides a window into this transition. The Qreiya 3 Lagerstätte [62.2 million years ago (Ma)] reveals an offshore marine ecosystem with at least 21 actinopterygian taxa across nine orders, exceeding the diversity of all other Danian skeletal assemblages combined. Most fishes are percomorphs and include the oldest skeleton-based records for at least six ecologically divergent extant groups. These findings reinforce inferences of fish extinction linked to the K-Pg and the rapid establishment of compositionally modern communities, marked by the first occurrences of new lineages no later than ~4 million years (Myr) after the event. Comparisons across sites indicate that percomorphs appear more common at lower paleolatitudes in the Paleocene, expanding into higher paleolatitudes by the Eocene.