Although shells in ancient deposits were accepted as preserved remnants of ancient organisms by Greek philosophers, this fundamental idea was essentially lost until the seventeenth century, and the science of palaeontology was not truly established until the nineteenth century. The progression of life demonstrated in the fossil record led to many advances in geology, most notably in biostratigraphy and delineation of the geological column. However, the contribution that palaeontology makes to the understanding of biological evolution by natural selection continues to be refined.