Gradual mass extinction, species survivorship, and long-term environmental changes across the Cretaceous-Tertiary boundary in high latitudes

Stable-isotope and planktic foraminiferal analyses across the Cretaceous/Tertiary (K/T) boundary transition at Nye Klov indicate long-term oceanic instability associated with global sea-level fluctuations, a gradual mass extinction, and decreased magnitude of the δ ¹³ C shift in high latitudes. Oceanic instability, which began at least 100 kyr before the K/T boundary and continued for about 300 kyr into the Tertiary, was accompanied by a gradual faunal turnover. No sudden mass extinction occurred in this cosmopolitan, high-latitude fauna, and nearly all Cretaceous taxa thrived well into the Tertiary, when they gradually disppeared. Long-term oceanic instability, gradual faunal turnover, absence of a sudden mass extinction, and greatly diminished δ ¹³ C shift in high latitudes suggest that a K/T boundary bolide impact was not the primary cause for the K/T boundary faunal transition. Moreover, these data strongly imply that the destructive effects of the bolide impact would have been greatest in low latitudes and negligible in high latitudes. -from Authors