Scientists examining sediments from the end of the dinosaur age has discovered microscopic carbon spheres that can be produced only from burning fossil fuels suggesting that the dinosaurs might have been wiped out at least partly by an oil-fueled conflagration.
The new potential explanation for the demise of the dinosaur derives from a component of the soot in the K-T sediments: distinctive carbon globs known as cenospheres. The microscopic spheres can form only when fossil hydrocarbons such as coal and crude oil burn.
Cenospheres were found at eight of 13 sites it examined around the world, and the objects were present only at the K-T boundary, not above or below it. The researchers suspect the Chicxulub object plowed into a huge oil reservoir in the Gulf of Mexico, like the ones feeding offshore platforms there today.
The impact first vaporized the oil and then ignited it in the atmosphere, causing an enormous, spreading fireball probably hundreds of kilometers wide. Whether the conflagration was enough to do in the dinos--via fire, soot, or global warming--remains unknown, but it would have spared a variety of critters, including the ancestors of today's mammals.
The paper is an "eye opener," says paleobotanist Peter Wilf of Pennsylvania State University in State College. It makes "a strong case for the true source of the mysterious soot" in the K-T layer and casts doubt "on the venerable global wildfire hypothesis," he says.
