Radioactive uranium-235 has a half-life of 704 million years. If it was incorporated into dinosaur bones, could it be used to date the dinosaur fossils?

Question

No, the dinosaurs went extinct too recently to use a radioisotope with a half-life of 704 million years.
Yes, but only for dinosaurs that lived more than 704 million years ago.
Yes, after 65.5 million years only about one tenth of the 235U would have decayed, leaving plenty to measure in the fossils.

Answer 1

The best answer is:

No, the dinosaurs went extinct too recently to use a radioisotope with a half-life of 704 million years.

Uranium-235's half-life is much longer than the age of the dinosaurs. Dinosaurs went extinct around 65.5 million years ago, which is a relatively short period compared to the half-life of uranium-235. As a result, using uranium-235 to date dinosaur fossils would not be effective or accurate, as the amount of uranium-235 remaining would be too small to measure reliably.