Chapter 2

Recall that \({ }^{14} \mathrm{C}\) has a half-life of 5,730 years. To calibrate the \(x\)-axis for \({ }^{14} \mathrm{C}\) decay, write the time before present in years below each half-life.

Carbon-14 dating works for fossils up to about 75,000 years old; fossils older than that contain too little \({ }^{14} \mathrm{C}\) to be detected. Most dinosaurs went extinct \(65.5\) million years ago. (a) Can \({ }^{14} \mathrm{C}\) be used to date dinosaur bones? Explain. (b) 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? Explain.