The Wheeler Formation has been previously dated to approximately 507 million year old, so we know the trilobite is also about 507 million years old.But, how can we determine how old a rock formation is, if it hasn’t previously been dated?
The reason was that the fossils of clams, snails, and other marine animals were found in tall mountains, miles from any ocean. Some religious writers believed that the shells were washed up during the Biblical flood.But this explanation could not account for the fact that fossils were not only found on mountains, but also within mountains, in rocks that had been quarried from deep below Earth's surface.Seeking an alternate explanation, other writers proposed that the fossils had formed within the rocks as a result of mysterious forces.In other words, fossil shells, bones, and teeth were never a part of a living creature! For Steno, the close resemblance between fossils and modern organisms was impossible to ignore.
Instead of invoking supernatural forces to explain fossils, Steno concluded that fossils were once parts of living creatures. There are two main methods determining a fossils age, relative dating and absolute dating.