What type of fossil dating technique would be most accurate for a trilobite from ~400 million years ago?

• A. Carbon-14 dating of the fossils itself.
• B. Carbon-14 dating of the surrounding volcanic ash.
• C. Uranium-238 dating of the surrounding volcanic ash.
• D. Uranium-238 dating of the fossils itself.

Answer: (C)

Verified step by step guidance

1. Step 1: Understand the age range of the fossil. Trilobites lived approximately 400 million years ago, which places them in the Paleozoic Era.
2. Step 2: Recognize the limitations of Carbon-14 dating. Carbon-14 dating is effective only for dating organic materials up to about 50,000 years old, so it is not suitable for fossils that are hundreds of millions of years old.
3. Step 3: Identify suitable radiometric dating methods for very old fossils. Uranium-238 dating is commonly used for dating rocks and minerals that are millions to billions of years old, making it appropriate for the age of trilobite fossils.
4. Step 4: Understand that fossils themselves often cannot be directly dated by radiometric methods because they are mineralized remains. Instead, the surrounding volcanic ash layers or igneous rocks are dated to estimate the fossil's age.
5. Step 5: Conclude that Uranium-238 dating of the surrounding volcanic ash is the most accurate technique for dating a trilobite fossil from around 400 million years ago.