The Great Dinosaur Extinction Controversy



In 1980 a scientific upheaval was triggered by the advent of the Alvarez-Berkeley group hypothesis. It explained the death of the dinosaurs and most of the life on Earth 65 million years ago by effects of the impact of a meteorite 10 km wide. Although numerous previous impact hypotheses had been largely ignored, that of the Alvarez group arrested the attention of scientists because it was based on an unprecedented form of evidence: highly anomalous concentrations of platinum group elements in seemingly meteoritic ratios within the pinkie-thick Cretaceous/Tertiary boundary clay.