Age, deposition and biotic effects of the Cretaceous/Tertiary boundary event at Mimbral, NE Mexico

The Mimbral outcrop in northeastern Mexico represents nearly continuous sedimentation across the Cretaceous/Tertiary (K/T) transition. The biotic effects of the K/T boundary event were not catastrophic for planktic foraminiferal faunas at Mimbral. Although 2/3 of the species disappeared at or below the K/T boundary, the effect on the overall foraminiferal population was small (<17%) because only rare, already endangered taxa disappeared. The limited biotic effects observed across the K/T boundary at Mimbral are consistent with other low latitude sections, and indicate that if a bolide impact occurred in the Caribbean, the biologic consequences were not as catastrophic as generally assumed even within a radius of 2000 miles. -from Authors