Conodonts in biostratigraphy. A 300-million-years long journey through geological time.

Conodonts are tooth-like elements of a primitive chordate and are generally abundant in many marine sedimentary rocks deposited from the late Cambrian to the latest Triassic. For all this time interval, more than 300 million years, conodonts represent the best tool for biostratigraphic studies. Conodonts are also widely used in paleoecologic, paleogeographic, and geochemical studies, making them the most useful fossil to investigate the Earth’s history during the “Conodontozoic”. A summary of the present knowledge on conodonts is presented, mainly focused on their stratigraphic applications. Biozonation schemes in use are discussed and the importance of these fossils in chronostratigraphic correlation is stressed.