Diamonds not a dinosaur's best friend - evidence for a dusting of microscopic diamonds at the time of the dinosaurs' extinction

Science News, Sept 7, 1991

As the last remaining dinosaurs neared their end, a dusting of microscopic diamonds apparently fell from the sky, according to a scenario proposed by two Canadian researchers who found extremely tiny diamonds in 65-million-year-old rocks from Alberta. That time corresponds to the mass extinctions that wiped out the last dinosaurs as well as many other animal and plant species at the end of the Cretaceous period.

David B. Carlisle of Environment Canada in Ottawa and Dennis R. Braman of the Royal Tyrrell Museum of Palaeontology in Drummheller, Alberta, isolated micrograins of carbon having diamond-like properties from the Alberta rocks. Each diamond measures 3 to 5 nanometers across, they report in the Aug. 22 NATURE. The diamonds are so small that "1,000 of them strung end to end would make a necklace for a bacterium, if bacteria had necks," says Carlisle.

He and Braman believe the microdiamonds may have some connection with the mass death at the end of the Cretaceous. Over the last decade, scientists have accumulated evidence that a meteorite or comet struck Earth at that time and caused the extinctions. The Canadian researchers suggest the diamond dust was either brought to Earth by the impacting meteorite or created during the high-pressure collission. The impact would have lofted the diamond dust and other rocky debris high into the atmosphere, blocking out sunlight and causing a wide range of environmental problems. With time, the diamonds then fell to Earth, the researchers suggest.