Late Night Science (documentary). Tonight: “The Iridium Conundrum.” The discovery of high concentrations of iridium in the so-called K-T boundary, which marks the extinction of the dinosaurs, has often been cited as evidence that the mass extinction was caused by a large asteroid impact, iridium being rare on earth but common in asteroids. One scientist, however, has proposed an alternative theory. Dr. Barnaby Droop of the Duck Hollow University Department of Geology and Calligraphy points out that iridium is also commonly found in fountain-pen nibs. He suggests that the high concentration in the K-T boundary marks an explosion in the population of lawyers, indicating that the extinction of the dinosaurs was brought about by overwhelmingly massive lawsuits. Check local listings.