''Pentagnostus'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

trilobite Trilobites (; meaning "three lobes") are extinct marine arthropods that form the class Trilobita. Trilobites form one of the earliest-known groups of arthropods. The first appearance of trilobites in the fossil record defines the base of the ...

s restricted to the

Middle Cambrian Middle or The Middle may refer to: * Centre (geometry), the point equally distant from the outer limits. Places * Middle (sheading), a subdivision of the Isle of Man * Middle Bay (disambiguation) * Middle Brook (disambiguation) * Middle Creek ...

. Its remains have been found in Siberia, Australia, North America,

Scandinavia Scandinavia; Sámi languages: /. ( ) is a subregion in Northern Europe, with strong historical, cultural, and linguistic ties between its constituent peoples. In English usage, ''Scandinavia'' most commonly refers to Denmark, Norway, and Swe ...

, and

Kazakhstan Kazakhstan, officially the Republic of Kazakhstan, is a transcontinental country located mainly in Central Asia and partly in Eastern Europe. It borders Russia to the north and west, China to the east, Kyrgyzstan to the southeast, Uzbeki ...

Taxonomy

The probable ancestor of ''Pentagnostus'' is

Archaeagnostus ''Archaeagnostus'' is an extinct genus from a well-known class of fossil marine arthropods, the trilobite Trilobites (; meaning "three lobes") are extinct marine arthropods that form the class Trilobita. Trilobites form one of the earliest ...

. Two subgenera can be distinguished. The nominate subgenus occurred first and developed into the later subgenus ''Pentagnostus (Meragnostus)'' and the family

Ptychagnostidae Ptychagnostidae is a family of agnostid trilobites from the 5th Stage to the Paibian Age of the Cambrian ( to million years ago). The family includes several important index fossils. Description Like all agnostids, ptychagnostids have cep ...

Species and distribution

Subgenus ''Pentagnostus (Pentagnostus)''

* ''P. anabarensis'' Lermontova, 1940 ( type) * ''P. ademptus'' (Prokovskaya and Jegorova, 1972) * ''P. brighamensis'' (Resser, 1938) * ''P. shergouldi'' Laurie, 2004 * ''P. veles'' Öpik, 1979 synonym ''P. endemicus''.

Subgenus ''Pentagnostus (Meragnostus)''

* ''P. bonnerensis'' (Resser, 1939) ( type) synonyms ''P. admirabilis'' and ''Agnostus lautus''. * ''P. bulkurensis'' (Prokovskaya and Pregel, 1982) * ''P. remotus'' (Prokovskaya and Jegorova, 1969) * ''P. segmentus'' (Robison, 1964) * ''P. shabactensis'' Ergaliev, 2008 synonym ''Peronopsis ultima'' Ergaliev, 1980 non Poulsen 1960.

References

{{Taxonbar, from=Q7164963 Peronopsidae Agnostida genera Cambrian trilobites Cambrian trilobites of Australia Fossils of Kazakhstan Fossils of Russia Paleozoic life of British Columbia Cambrian genus extinctions