1638-1686

Danish anatomist and geologist, also known as Niels Steensen (or Stensen), whose landmark treatise The Prodromus of Nicolaus Steno's Dissertation Concerning a Solid Body Enclosed by Process of Nature Within a Solid (1669) advanced the study of geology and helped establish the science of crystallography. Steno described the structure of quartz crystals, suggested that fossils were the remains of ancient organisms, and that the study of the earth's strata could provide a history of the planet. His most famous anatomical contribution was the discovery of the parotid salivary duct, which is also known as Stensen's duct.