1. **Stating the problem:** The problem is to explain why carbon-14 dating cannot accurately date a dinosaur fossil to be 73 million years old. 2. **Understanding carbon-14 dating:** Carbon-14 dating is a method used to determine the age of organic materials by measuring the amount of radioactive carbon-14 isotope remaining. 3. **Important rule:** Carbon-14 has a half-life of about 5730 years, meaning after this time, half of the original carbon-14 decays. 4. **Reason 1 - Time limitation:** Because of the half-life, carbon-14 dating is only effective for samples up to about 50,000 to 60,000 years old. Beyond this, the remaining carbon-14 is so minimal it cannot be accurately measured. 5. **Reason 2 - Fossilization process:** Dinosaur fossils are mineralized, meaning the original organic carbon is replaced by minerals over millions of years, so no original carbon-14 remains to measure. 6. **Conclusion:** Therefore, carbon-14 dating cannot be used to date dinosaur fossils that are millions of years old, such as 73 million years, because the carbon-14 would have completely decayed and the fossil no longer contains organic carbon.