Would you expect to find dinosaur bones in a rock that was 250 million years old?

It is unlikely to find dinosaur bones in a rock that is 250 million years old. While some dinosaurs lived during that period, the vast majority of dinosaur fossils have been found in rocks that are less than 150 million years old. This is because dinosaurs, as we know them, evolved during a period called the Mesozoic Era, which lasted from about 250 million years ago to about 65 million years ago. The older rocks, from the Paleozoic Era, are generally less likely to contain dinosaur remains.