In other words, they may no longer be in their primary context.When the bones of our early ancestors are found in the same geological strata as those of other animals that are known to have lived only during a specific time period in the past, we assume that these ancestors must also have come from that time.These processes result in All of these processes confuse the stratigraphic record.In many cases, however, it is possible to reconstruct the original sequence of strata so that they can be used for relative dating.However, relative methods are , which is that if there are layers of deposits, those laid down first will be on the bottom and those laid down last will be on the top. However, geological strata are not always found to be in a neat chronological order.Wind and water erode strata and some areas are uplifted or even tilted.can be used to tell us whether or not the animals they were from actually lived at about the same time.For instance, if we find a fossil bone below the strata 3 rock level shown above, we assume that the animal most likely lived at a time before that layer was formed.
However, the assumption of contemporaneity may not always be correct.This is due to the fact that one or both of the objects may have been moved or redeposited into a different location.In the past, relative dating methods often were the only ones available to paleoanthropologists.As a result, it was difficult to chronologically compare fossils from different parts of the world.
This is referred to as dating by association with they underwent relatively rapid evolutionary changes that are identifiable in their teeth and other skeletal parts.
Their bones also were frequently found in association with our human and primate ancestors.