LIFE SCIENCE

Detailed explanation-1: -In the first method, age of a fossil is determined by depth at which it was found. A fossil from deeper layers is older than one from a shallower layer. Another method involves the use of carbon dating, which works on finding the level of C-14 (an isotope of carbon) in the fossil.

Detailed explanation-2: -As sediments carried by wind and water accumulate, they bury older layers-so the bottom layers in a geological sequence are usually the oldest and the top layers the youngest. Paleontologists can thus put fossils in chronological order without knowing the actual age of each specimen.

Detailed explanation-3: -To establish the age of a rock or a fossil, researchers use some type of clock to determine the date it was formed. Geologists commonly use radiometric dating methods, based on the natural radioactive decay of certain elements such as potassium and carbon, as reliable clocks to date ancient events.

Detailed explanation-4: -Because fossils are usually found in sedimentary rock layers, paleontologists can date them by examining the minerals above or below the sedimentary rock. Zircon, a mineral commonly found in igneous rocks, proves particularly useful.