The history of paleontology has been an ongoing effort to understand the history of life on Earth by understanding the fossil record left behind by living organisms. Inevitably it has been closely tied to geology and the effort to understand the history of the Earth itself. In the 17th and 18th centuries there was progress made in understanding the nature of fossils and the at the end of the 18th century the work of Georges Cuvier lead to the emergence of paleontology, in association with comparative anatomy, as a scientific discipline. The expanding knowledge of the fossil record also played an increasing role in the development of geology, particularly stratigraphy. The first half of the 19th century saw a rapid increase in knowledge about the past history of life on Earth and the progress towards definition of the geologic time scale. After Charles Darwin published the Origin of Species in 1859, much of the focus of paleontology shifted to understanding evolutionary paths, including human evolution, and evolutionary theory. The last half of the 20th century saw a renewal of interest in mass extinctions and their role in history of life on Earth.
As early as the 6th century BC Xenophanes of Colophon recognized that some fossil shells were remains of shellfish and indicated that what was now dry land was once under the sea. It is also well known that in one of his unpublished notebooks Leonardo da Vinci (1452-1519) concluded that some fossil sea shells were the remains of shellfish. However in both cases it is clear that the fossils were relatively complete remains of mollusk species that very closely resembled living species and thus were relatively easy to classify.