Pentagnostus

Pentagnostus; Temporal range:
	Pentagnostus brighamensis, 6mm, Spence Formation
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Clade:	†Artiopoda
Class:	†Trilobita (?)
Order:	†Agnostida
Family:	†Peronopsidae
Genus:	†Pentagnostus; Lermontova, 1940
Subgenera
	Pentagnostus (Pentagnostus); Pentagnostus (Meragnostus) Naimark, 2012; and see text for species

Pentagnostus is a genus of small, blind, agnostid trilobites restricted to the Middle Cambrian. Its remains have been found in Siberia, Australia, North America, Scandinavia, and Kazakhstan.^[1]

Taxonomy

Schematic showing the relationship between both subgenera of *Pentagnostus* (light green), the ancestral *Archaeagnostus* (darker green) and the descending Ptychagnostidae (red). Based on E. B. Naimark (2012). Hundred species of the genus *Peronopsis* Hawle et Corda, 1847. Paleontological Journal 46(9):945-1057

The probable ancestor of Pentagnostus is Archaeagnostus. Two subgenera can be distinguished. The nominate subgenus occurred first and developed into the later subgenus Pentagnostus (Meragnostus) and the family Ptychagnostidae.^[1]

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.^[1]
P. praecurrens (Westergård, 1936)^[2]

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.^[1]

References

1 2 3 4 5 Naimark, E.B. (2012). "Hundred species of the Genus Peronopsis Hawle et Corda, 1847". Paleontological Journal. 46 (9): 945–1057. Bibcode:2012PalJ...46..945N. doi:10.1134/S0031030112090018. S2CID 85130465.
↑ Laurie, John. "The Westergård specimens of the early Middle Cambrian agnostid Pentagnostus praecurrens (Westergård, 1936)". {{cite journal}}: Cite journal requires |journal= (help)

[Naimark-1] 1 2 3 4 5 Naimark, E.B. (2012). "Hundred species of the Genus Peronopsis Hawle et Corda, 1847". Paleontological Journal. 46 (9): 945–1057. Bibcode:2012PalJ...46..945N. doi:10.1134/S0031030112090018. S2CID 85130465.

[2] Laurie, John. "The Westergård specimens of the early Middle Cambrian agnostid Pentagnostus praecurrens (Westergård, 1936)". {{cite journal}}: Cite journal requires |journal= (help)

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