Usually to begin they use the process of relative dating,
then chemical dating. Then look at where the environment that we found the
fossil to determine if it has always been that environment. When fossil is found in marine life in a
country town suggesting that the environment was previously a marine
environment. Study the rocks that they
found the fossils to help determine a relative age. This came before that, but
after them to give us an approximate age. Then study the fossil itself to
classify it into groups to determine which branch of evolution it has come
from. Fossils can be found in rocks, bedding planes, (rock layers), trees (tree
ring dating). Mostly there are found in rocks or weathered rocks (sands, mud).
What does Earth have that other planets don't, the basis of life? Water, of course. Humans and other mammals drink specifically <em>freshwater</em> though, which is far more precious and less abundant than saltwater.
