The cover story in the June 2002 Discover magazine (Vol. 23 No. 6) “What Wiped Out the Dinosaurs?” features research and quotes by Nan Crystal Arens, assistant professor of geoscience. The article is about research being done at a micro-site of fossils. Theories based on the research hypothesize that the common explanation for the extinction of the dinosaurs–a massive asteroid impact–doesn't fully account for their disappearance. Fossil leaves and pollen excavated show that the diversity of flowering plants substantially decreased in patches throughout the region before the asteroid impact. Arens speculates that as the vegetation became patchier, herbivore dinosaurs and the carnivores that ate them began to disappear.
The following link http://www.discover.com/june_02/featdino.html goes to the Discover Web site, which has the first paragraph from the article posted.