You should see a white crescent called the lunula. The cuticle is the piece of skin that overlaps the hard nail and touches the lunula. You may be wondering what they do, or why you need them. If you get frequent manicures, they may be smooth and even, pushed back as far as they'll go.If not, they may be ragged and torn, or creeping up on the nail.he cuticle is the piece of skin that overlaps the hard nail and touches the lunula. You may be wondering what they do, or why you need them. If you get frequent manicures, they may be smooth and even, pushed back as far as they'll go.
Index fossils. Radiometric dating. The Age of Dinosaurs was so many millions of years ago that it is very difficult to date exactly. Scientists use two kinds of dating techniques to work out the age of rocks and fossils. The first method is called relative dating.
Some minerals in rocks and organic matter (e.g., wood, bones, and shells) can contain radioactive isotopes. The abundances of parent and daughter isotopes in a sample can be measured and used to determine their age. This method is known as radiometric dating. Some commonly used dating methods are summarized in Table 1.