In 1982, at a dinosaur site in the blazing heat of the central Indian city of Jabalpur, Sahni remembers covering every inch of ground in search of fossils. When he bent over to tie his shoelaces, right there in front of him were four or five spherical structures, measuring 16-20cm in length. "These were very weathered, round, roughly of equal shape. I was stunned. Could they be dinosaur eggs?"