A paleontologist finds a new tyrannosaur in a site she is excavating, and wishes to date the fossil. What is the most likely method she will use? A paleontologist finds a new tyrannosaur in a site she is excavating, and wishes to date the fossil. What is the most likely method she will use? She will measure the amount of the radioisotope uranium-238 in the stratum where she found the tyrannosaur. She will determine the fossil’s age by measuring the ratio of carbon-14 to carbon-12 in the fossil. She will infer the age of the fossil by dating layers of volcanic rock above and below the stratum containing the fossil.