Generally Scientists are informed by Darwinian Evolution in interpreting the fossil record.
Darwin's theory of descent with modification creates a general rule that the simpler fossils are the oldest fossils. The fossil record then is arranged in accordance with Darwin's theory of evolution.
When bird seed is poured into a container the smallest pieces settle to the bottom and the largest pieces are found on the top. A similar process is found in sedimentary layers, The smallest simplest fossils are generally found in the bottom layers while larger more complex fossils are generally found in the top layers.
The law of superimposition says that the oldest layers are on the bottom while the younger layers are on the top. The rule makes sense. However in many locations more complex fossils are found in layers beneath layer with simpler fossils. The complex fossils are still considered to be younger in violation of the law of superimposition.
The theory of Darwinian evolution requires that there has been a general movement from the simple to the complex, That there has been an increase in complexity of information found in living things.
This principle is what has been used to develop the fossils record.