A fossil is defined as any trace of a past life form.
Thus, although wood, bones, and shells are the most common fossils, under certain conditions soft tissues, tracks and trails, and even coprolites (fossil feces) may be preserved as fossils.
This technique does not depend on knowing the actual numerical ages of the rocks.
Formal education is not a prerequisite for becoming a paleontologist.
What's needed is a keen analytical mind, curiosity and imagination tempered by scientific rigor, and lots of patience to keep visiting sites, to keep good notes, and to familiarize yourself with what is known about the fossils and time period that you are studying.
However, archaeologists and paleontologists might work together.
For instance, a paleontologist might identify fossil animal bones or plant pollen associated with an archaeological site, to find out what the people who lived there ate; or a paleontologist might be called on to analyze the climate at the time a particular archaeological site was inhabited.
Paleontologists can provide historical data on past climates and apply it towards understanding future trends and their likely effects.
If we understand the effects of climate change, for instance, on our world in the past, we can understand its probable effects in the future.
Finally, paleontology is an increasingly important component of historical biology.
The life around us today has been shaped through its long history, and understanding its past is important to understanding its present situation.
However, many sedimentary rocks cannot be dated directly by these methods; dates usually are obtained from igneous rocks within a sedimentary sequence, such as lava flows or ash beds.