Ichthyolith accumulation and age models from DSDP 527, DSDP 596, ODP 886, ODP 1209, and Gubbio

Extinction scenarios have suggested that a collapse of phytoplankton production rippled up the food chain causing wholesale loss of consumers and top predators. Pelagic fishes represent a key trophic link between primary producers and top predators and provide a means to examine the influence of trophic relationships during extinctions.

Here we show that there is geographic heterogeneity in the abundance of fishes through the mass extinction using the accumulation rate of ichthyoliths (i.e., microscopic fish teeth and shark dermal scales). In the Tethys Sea, fish abundance falls abruptly at the boundary and remains depressed for at least 3 million years. In contrast, fish abundance in the Pacific Ocean remained at or above pre-boundary levels for at least four million years following the mass extinction, despite drastic extinctions in co-occurring primary producers and zooplankton consumers.