The remnants of DNA may lurk in 125 million-year-old dinosaur fossils found in China. If the microscopic structures are indeed DNA, they would be the oldest recorded preservation of chromosome material in a vertebrate fossil.   Researchers have reported possible cell nucleus structures in fossils of plants and algae dating back millions of years. These claims are often controversial, because it can be hard to distinguish a fossilized nucleus from a random blob of mineralization created duri