The extinction of the dinosaurs at the Cretaceous-Tertiary (K-T) boundary about 65 million years ago has been traced to the impact of a large object. The fossil record of insect extinction at the K-T boundary is not as clear, and it has been assumed that insects were better able to survive the impact because of their small size, flexible lifestyles, and overall abundance.
Labandeira et al. analyzed 13,000 fossil plant specimens collected from above and below the K-T boundary at Williston Basin, North Dakota. For each plant, they cataloged any signs of the presence of herbivorous insects, such as holes created by feeding. Across the 51 types of plant-insect associations, most of the insects that were specialized for feeding on one kind of plant became extinct at the K-T boundary. These results also suggest that the plant-insect diversity bottleneck, which spans the first 10 million years of the Tertiary in the fossil record of Wyoming, may have been precipitated by the impact event. -- LR
Proc. Natl. Acad. Sci. U.S.A. 99, 2061 (2002).
