<P> And we find oysters together in very large families, among which some may be seen with their shells still joined together, indicating that they were left there by the sea and that they were still living when the strait of Gibraltar was cut through . In the mountains of Parma and Piacenza multitudes of shells and corals with holes may be seen still sticking to the rocks ..." </P> <P> Robert Hooke (1635 - 1703) included micrographs of fossils in his Micrographia and was among the first to observe fossil forams . His observations on fossils, which he stated to be the petrified remains of creatures some of which no longer existed, were published posthumously in 1705 . </P> <P> William Smith (1769--1839), an English canal engineer, observed that rocks of different ages (based on the law of superposition) preserved different assemblages of fossils, and that these assemblages succeeded one another in a regular and determinable order . He observed that rocks from distant locations could be correlated based on the fossils they contained . He termed this the principle of faunal succession . This principle became one of Darwin's chief pieces of evidence that biological evolution was real . </P> <P> Georges Cuvier came to believe that most if not all the animal fossils he examined were remains of extinct species . This led Cuvier to become an active proponent of the geological school of thought called catastrophism . Near the end of his 1796 paper on living and fossil elephants he said: </P>

Which group of organisms some of which were preserved as fossils