Bolide impact triggered the
Late Triassic extinction event in
equatorial Panthalassa
Extinctions within major pelagic groups (e.g., radiolarians and conodonts) occurred in a stepwise
fashion during the last 15 Myr of the Triassic. Although a marked decline in the diversity of pelagic
faunas began at the end of the middle Norian, the cause of the middle Norian extinction is uncertain.
Here we show a possible link between the end-middle Norian radiolarian extinction and a bolide impact.
Two palaeoenvironmental events occurred during the initial phase of the radiolarian extinction interval:
(1) a post-impact shutdown of primary and biogenic silica production within a time span of 104–105
yr, and (2) a sustained reduction in the sinking flux of radiolarian silica for ~0.3 Myr after the impact.
The catastrophic collapse of the pelagic ecosystem at this time was probably the dominant factor
responsible for the end-middle Norian conodont extinction.