''Streptognathodus'' is an extinct genus of

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 from the

Late Carboniferous Late may refer to: * LATE, an acronym which could stand for: ** Limbic-predominant age-related TDP-43 encephalopathy, a proposed form of dementia ** Local-authority trading enterprise, a New Zealand business law ** Local average treatment effect, ...

Early Permian 01 or '01 may refer to: * The year 2001, or any year ending with 01 * The month of January * 1 (number) Music * '01 (Richard Müller album), 01'' (Richard Müller album), 2001 * 01 (Son of Dave album), ''01'' (Son of Dave album), 2000 * 01 (Urban ...

Use in stratigraphy

Late Carboniferous

The top of the

Kasimovian The Kasimovian is a geochronology, geochronologic age (geology), age or chronostratigraphy, chronostratigraphic stage (stratigraphy), stage in the International Commission on Stratigraphy, ICS geologic timescale. It is the third stage in the Penn ...

stage is close to the first appearance of ''Streptognathodus zethus''. The

golden spike The golden spike (also known as The Last Spike) is the ceremonial 17.6-karat gold final spike driven by Leland Stanford to join the rails of the first transcontinental railroad across the United States connecting the Central Pacific Railroad ...

for the Kasimovian stage has not yet been assigned (in 2008). The Kasimovian is subdivided into three conodont

biozone In biostratigraphy, biostratigraphic units or biozones are intervals of geological strata that are defined on the basis of their characteristic fossil taxa, as opposed to a lithostratigraphic unit which is defined by the lithological properties of ...

s: *''

Idiognathodus ''Idiognathodus'' is an extinct conodont genus in the family Idiognathodontidae. Use in stratigraphy The species ''Idiognathodus simulator'' made its first appearance during the Gzhelian, the youngest age of the Pennsylvanian (late Carbonife ...

toretzianus'' Zone *''Idiognathodus sagittatus'' Zone *''Streptognathodus excelsus'' and ''Streptognathodus makhlinae'' Zone The base of the

Gzhelian The Gzhelian ( ) is an age in the ICS geologic timescale or a stage in the stratigraphic column. It is the youngest stage of the Pennsylvanian, the youngest subsystem of the Carboniferous. The Gzhelian lasted from to Ma. It follows the Kasim ...

is at the first appearance of ''Streptognathodus zethus''. The top of the stage (also the top base of the Silesian and the base of the Permian system) is at the first appearance of ''Streptognathodus isolatus'' within the ''Streptognathus "wabaunsensis"'' chronocline. The Gzhelian stage is subdivided into five

s, based on the conodont genus ''Streptognathodus'': * ''Streptognathodus wabaunsensis'' and ''Streptognathodus bellus'' Zone * ''Streptognathodus simplex'' Zone * ''Streptognathodus virgilicus'' Zone * ''Streptognathodus vitali'' Zone * ''Streptognathodus simulator'' Zone

Early Permian

The base of the

Asselian In the geologic timescale, the Asselian is the earliest geochronologic age or lowermost chronostratigraphic stage of the Permian. It is a subdivision of the Cisuralian Epoch or Series. The Asselian lasted between and million years ago (Ma). It ...

stage is at the same time the base of the

Cisuralian The Cisuralian is the first Series (stratigraphy), series/Epoch (geology), epoch of the Permian. The Cisuralian was preceded by the Pennsylvanian (geology), Pennsylvanian and followed by the Guadalupian. The Cisuralian Epoch is named after the w ...

series and the Permian system. It is defined as the place in the stratigraphic record where

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

s of the species ''Streptognathodus isolatus'' first appear. The global reference profile for the base (the GSSP or golden spike) is located in the valley of the Aidaralash River, near

Aqtöbe Aktobe ( kz, Ақтөбе, Aqtöbe; russian: Актобе, Aktobe) is a city on the Ilek River in Kazakhstan. It is the administrative center of Aktobe Region. In 2020, it had a population of 500,757 people. Aktobe is located in the west of Ka ...

in the Ural Mountains of Kazakhstan.The GSSP was first proposed by Davydov ''et al.'' (1998) The top of the Asselian stage (the base of the

Sakmarian In the geologic timescale, the Sakmarian is an age or stage of the Permian. It is a subdivision of the Cisuralian Epoch or Series. The Sakmarian lasted between 293.52 and million years ago (Ma). It was preceded by the Asselian and followed by t ...

stage) is at the first appearance of the species ''Streptognathodus postfusus''. The Asselian contains five conodont

s: *zone of ''Streptognathodus barskovi'' *zone of ''Streptognathodus postfusus'' *zone of ''Streptognathodus fusus'' *zone of ''Streptognathodus constrictus'' *zone of ''Streptognathodus isolatus'' The base of the

stage is laid with the first appearance of ''Streptognathodus postfusus'' in the fossil record. A global reference profile for the base had in 2009 not yet been appointed. The top of the Sakmarian (the base of the Artinskian) is defined as the place in the stratigraphic record where fossils of conodont species ''

Sweetognathus whitei ''Sweetognathus'' is an extinct genus of conodonts in the family Sweetognathidae that evolved at the beginning of the Permian period (298.9 Ma), in near-equatorial, shallow-water seas. The genus is characterized by pustulose ornamentation on a ...

'' and ''

Mesogondolella bisselli ''Mesogondolella'' is an extinct genus of conodonts. The species ''M. daheshenensis'' and ''M. subgracilis'' are from the Permian (probably Wordian) of the Daheshen Formation in China.The age of the Daheshen Formation in Jilin Province based o ...

'' first appear.

References

External links

* * Ozarkodinida genera Carboniferous conodonts Permian conodonts Asselian life Gzhelian life Kasimovian life Pennsylvanian first appearances Cisuralian genus extinctions {{conodont-stub