According to the fossil record, one minute they were there - and the next they were gone. What happened 65 million years ago? John Maddox discusses with Drs Luis and Walter Alvarez , of the University of California at Berkeley, why they believe that it was an Apollo asteroid, ploughing into the surface of the earth, which led to the disappearance not only of the dinosaurs, but of three-quarters of the plant and animal species then alive.
Producer ALISON RICHARDS (First broadcast on R3) long wave only