''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 ...
of
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
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* 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
![Gradogram Pentagnostus](https://upload.wikimedia.org/wikipedia/commons/8/85/Gradogram_Pentagnostus.jpg)
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