Pentagnostus

Pentagnostus is a genus of trilobites restricted to the Middle Cambrian. Its remains have been found in Siberia, Australia, North America, Scandinavia, and Kazakhstan.

Pentagnostus Temporal range:
Pentagnostus brighamensis, 6mm, Spence Formation
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Trilobita
Order:	Agnostida
Suborder:	Agnostina
Superfamily:	Agnostoidea
Family:	Peronopsidae
Genus:	Pentagnostus Lermontova, 1940
subgenera
Pentagnostus (Pentagnostus) Pentagnostus (Meragnostus) Naimark, 2012 and see text for species

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.

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.