page_title: History of paleontology
section_title: 17th century
hierarchical_section_title: History of paleontology / 17th century
caption_attribution_description: English: White shark and shark teeth from Steno's Elementorum myologiæ specimen, seu musculi descriptio geometrica&#160;: cui accedunt Canis Carchariæ dissectum caput, et dissectus piscis ex Canum genere Čeština: Kresba žraloka od Nicolase Stena
context_page_description: The history of paleontology traces the history of the effort to understand the history of life on Earth by studying the fossil record left behind by living organisms. Since it is concerned with understanding living organisms of the past, paleontology can be considered to be a field of biology, but its historical development has been closely tied to geology and the effort to understand the history of Earth itself.
  In ancient times, Xenophanes, Herodotus, Eratosthenes, and Strabo wrote about fossils of marine organisms, indicating that land was once under water. The ancient Chinese considered them to be dragon bones and documented them as such. During the Middle Ages, fossils were discussed by Persian naturalist Ibn Sina in The Book of Healing, which proposed a theory of petrifying fluids that Albert of Saxony would elaborate on in the 14th century. The Chinese naturalist Shen Kuo would propose a theory of climate change based on evidence from petrified bamboo.
  In early modern Europe, the systematic study of fossils emerged as an integral part of the changes in natural philosophy that occurred during the Age of Reason.
context_section_description: During the Age of Reason, fundamental changes in natural philosophy were reflected in the analysis of fossils. In 1665 Athanasius Kircher attributed giant bones to extinct races of giant humans in his Mundus subterraneus. In the same year Robert Hooke published Micrographia, an illustrated collection of his observations with a microscope. One of these observations was entitled "Of Petrify'd wood, and other Petrify'd bodies", which included a comparison between petrified and ordinary wood. He concluded that petrified wood was ordinary wood that had been soaked with "water impregnated with stony and earthy particles". He then suggested that several kinds of fossil sea shells were formed from ordinary shells by a similar process. He argued against the prevalent view that such objects were "Stones form'd by some extraordinary Plastick virtue latent in the Earth itself". Hooke believed that fossils provided evidence about the history of life on Earth writing in 1668:
  ...if the finding of Coines, Medals, Urnes, and other Monuments of famous persons, or Towns, or Utensils, be admitted for unquestionable Proofs, that such Persons or things have, in former times had a being, certainly those Petrifactions may be allowed to be of equal Validity and Evidence, that there have formerly been such Vegetables or Animals... and are true universal Characters legible to all rational Men. 
  Hooke was prepared to accept the possibility that some such fossils represented species that had become extinct, possibly in past geological catastrophes.
  In 1667 Nicholas Steno wrote a paper about a shark head he had dissected. He compared the teeth of the shark with the common fossil objects known as "tongue stones" or glossopetrae.  He concluded that the fossils must have been shark teeth. Steno then took an interest in the question of fossils, and to address some of the objections to their organic origin he began studying rock strata. The result of this work was published in 1669 as Forerunner to a Dissertation on a solid naturally enclosed in a solid. In this book, Steno drew a clear distinction between objects such as rock crystals that really were formed within rocks and those such as fossil shells and shark teeth that were formed outside of those rocks. Steno realized that certain kinds of rock had been formed by the successive deposition of horizontal layers of sediment and that fossils were the remains of living organisms that had become buried in that sediment. Steno who, like almost all 17th century natural philosophers, believed that the earth was only a few thousand years old, resorted to the Biblical flood as a possible explanation for fossils of marine organisms that were far from the sea.
  Despite the considerable influence of Forerunner, naturalists such as Martin Lister (1638–1712) and John Ray (1627–1705) continued to question the organic origin of some fossils. They were particularly concerned about objects such as fossil Ammonites, which Hooke claimed were organic in origin, that did not resemble any known living species. This raised the possibility of extinction, which they found difficult to accept for philosophical and theological reasons. In 1695 Ray wrote to the Welsh naturalist Edward Lluyd complaining of such views: "... there follows such a train of consequences, as seem to shock the Scripture-History of the novity of the World; at least they overthrow the opinion received, & not without good reason, among Divines and Philosophers, that since the first Creation there have been no species of Animals or Vegetables lost, no new ones produced."
caption: Illustration from Steno's 1667 paper shows a shark head and its teeth along with a fossil tooth for comparison.
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