Return of the Asteroid

No, not some 1950s B-movie, but the once-accepted, sometimes doubted, and, now, revived idea that the great extinction at the end of the Cretaceous some 65.5 mya was caused by an asteroid impacting the earth in the area Chicxulub, Mexico on the the Yucatan Peninsula. This extinction event, represented in sedimentary layers at was once known as the K-T (Cretaceous-Tertiary) and now more properly called the K-Pg (Cretaceous-Paleogene) boundary, claimed almost all species of large land vertebrates, along with a significant percentage of marine invertebrates, land plants, and other taxa. It's most commonly associated, of course, with the disappearance of the dinosaurs - for that reason, it's undoubtedly the mass extinction that resonates most clearly with the general public (with the possible exception of the one that we're currently creating). The asteroid theory has been around since the 1970s, when Walter and Luis Alvarez noted the presence of a iridium-rich deposits at the K-Pg boundary. The later discovery of the Chicxulub crater was seen to be the smoking gun. However, a number of other possible contributing factors have been identifed, notably Indian flood basalt volcanism that occurred at roughly the same time. In the current study, the authors correlate data from global stratigraphy across the boundary with the onset of the extinction event. They feel the evidence conclusively supports the killer asteroid as the instigator. Next?