Like DNA, RNA polymers are make up of chains of nucleotides *. These nucleotides have three parts: 1) a five carbon ribose sugar, 2) a phosphate molecule and 3) one of four nitrogenous bases: adenine, guanine, cytosine or uracil.
Index fossils are used by scientists to help them figure out the dating of discovered fossils or the correlation. They are also very known to appear in a (very) certain/specific age range.
