''Iapetognathus'' is a genus of cordylodan

conodont Conodonts (Greek ''kōnos'', "cone", + ''odont'', "tooth") are an extinct group of agnathan (jawless) vertebrates resembling eels, classified in the class Conodonta. For many years, they were known only from their tooth-like oral elements, which ...

s. It is one of the oldest denticulate euconodont genera known.The conodont Iapetognathus and its value for defining the base of the Ordovician System. Frederick Miller, John E. Repetski, Robert S. Nicoll, Godfrey Nowlan and Raymond L. Ethington, GFF, Volume 136, Issue 1, 2014, pages 185-188, Like other members of the genus, ''

Iapetognathus fluctivagus ''Iapetognathus fluctivagus'' is a species of denticulate cordylodan conodonts belonging to the genus '' Iapetognathus''. It existed during the Tremadocian Age ( million years ago) of the Ordovician. It is an important index fossil in biostratig ...

'' had ramiform (branching) array of elements (apparatus). It is believed that the ramiform apparatus in ''Iapetognathus fluctivagus'' evolved from the coniform (cone-like) apparatus of '' Iapetonudus ibexensis''. It can be readily distinguished from other conodonts existing during the same age by the sideward orientation of the major teeth-like projections (denticulate processes). The genus ''Iapetognathus'' and related denticulate groups still require extensive taxonomic clarification. In 2011, a study discovered that the

First appearance datum First appearance datum (FAD) is a term used by geologists and paleontologists to designate the first appearance of a species in the geologic record. FADs are determined by identifying the geologically oldest fossil discovered, to date, of a particu ...

(FAD) of ''Iapetognathus fluctivagus'' in the

Global Boundary Stratotype Section and Point A Global Boundary Stratotype Section and Point (GSSP) is an internationally agreed upon reference point on a stratigraphic section which defines the lower boundary of a stage on the geologic time scale. The effort to define GSSPs is conducted b ...

(GSSP) section in Green Point may not actually be the earliest species of ''Iapetognathus'' to appear as was earlier believed. Its true FAD lies above another species, '' Iapetognathus preaengensis'', and is not present at the

Cambrian The Cambrian Period ( ; sometimes symbolized C with bar, Ꞓ) was the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million ...

–

Ordovician The Ordovician ( ) is a geologic period and System (geology), system, the second of six periods of the Paleozoic Era (geology), Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start ...

boundary (COBWG). The authors of the study recommended a reevaluation of the Green Point GSSP section, as well as possible redefinitions of the associated horizons using other

index fossil Biostratigraphy is the branch of stratigraphy which focuses on correlating and assigning relative ages of rock Stratum, strata by using the fossil assemblages contained within them.Hine, Robert. “Biostratigraphy.” ''Oxford Reference: Dictiona ...

References

External links

''Iapetognathus''
at

fossilworks Fossilworks is a portal which provides query, download, and analysis tools to facilitate access to the Paleobiology Database The Paleobiology Database is an online resource for information on the distribution and classification of fossil animals ...

.org (retrieved 24 April 2016) {{Taxonbar, from=Q20679041 Proconodontida genera Early Ordovician animals Ordovician conodonts

See also

References

External links