Ptychagnostus

Ptychagnostus; Temporal range: Middle Cambrian PreꞒ Ꞓ O S D C P T J K Pg N
	Ptychagnostus germanus
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	†Trilobita (?)
Order:	†Agnostida
Family:	†Ptychagnostidae
Genus:	†Ptychagnostus; Jaekel, 1909
Synonyms
	Triplagnostus Linnarsson, 1869; Huarpagnostus Rusconi, 1950; Solenagnostus Whitehouse, 1936; Pentagnostus Lermontova, 1940; Aristarius Opik, 1979; Aotagnostus Opik, 1979; Acidusus Opik, 1979; Canotagnostus Rusconi, 1951; Zeteagnostus Opik, 1979;

Ptychagnostus is a member of the agnostida that lived during the Cambrian period. Ptychagnostidae generally do not exceed one centimetre in length.^[1] Their remains are rarely found in empty tubes of the polychaete worm Selkirkia.^[2] The genus probably ranged throughout the water column. It has two glabellar lobes, and three pygidial lobes.^[3]

Type species

Agnostus punctuosus Angelin, 1851 from the Pt. punctuosus Zone of the Alum Shale (Drumian), Sweden (by original designation). Official ruling on the conservation of accepted usage of A. punctuosus as the type species was given by the International Commission on Zoological Nomenclature, 1993.

Remarks

Ptychagnostus affinis (Brøgger 1878) ^[4] was once considered a subspecies of Pt. punctuosus. Laurie (2008) ^[5] grouped punctuosus and affinis within Ptychagnostus, but preferred to place the closely related atavus within Acidusus.

Ptychagnostidae Genera

Høyberget & Bruton (2008) ^[6] concluded that the following genera belong in the Ptychagnostidae: Ptychagnostus, Goniagnostus, Tomagnostus, Lejopyge, Aotagnostus and Onymagnostus.

Species

Ptychagnostus punctuosus (Type species).
Ptychagnostus affinis (formerly Pt. punctuosus affinis)
Ptychagnostus aculeatus
Ptychagnostus akanthodes
Ptychagnostus atavus
Ptychagnostus cassis
Ptychagnostus ciceroides
Ptychagnostus cuyanus
Ptychagnostus germanus
Ptychagnostus gibbus
Ptychagnostus hybridus
Ptychagnostus intermedius
Ptychagnostus michaeli
Ptychagnostus praecurrens
Ptychagnostus seminula

References

^ ^a ^b Samuel M. Gon III. "Agnostida Fact Sheet". A Guide to the Orders of Trilobites. Retrieved 18 November 2012.
^ Brian D. E. Chatterton, Desmond H. Collins & Rolf Ludvigsen (2003). "Cryptic behaviour in trilobites: Cambrian and Silurian examples from Canada, and other related occurrences". In Philip D. Lane, Derek J. Siveter & Richard A. Fortey (ed.). Trilobites and their Relatives: contributions from the third international conference, Oxford 2001. Special Papers in Palaeontology. Vol. 70. pp. 157–173. ISBN 978-0-901702-81-4.
^ Coppold, Murray and Wayne Powell (2006). A Geoscience Guide to the Burgess Shale, p.56. The Burgess Shale Geoscience Foundation, Field, British Columbia. ISBN 0-9780132-0-4.
^ BRØGGER W. C. 1878. Om paradoxides-skifrene ved Krekling. Nyt Magazin for Naturvidens-kaberne 24, 18–88.
^ LAURIE J. R. 2008. Species relationships in the Ptychagnostidae (Cambrian, Agnostina). In: Ra´bano I., Gozalo R. & GarciaBellido D. eds. Advances in trilobite research, pp. 211–218. Cuadernos del Museo Geominero 9.
^ HØYBERGET M. & BRUTON D. L. 2008. Middle Cambrian trilobites of the suborders Agnostina and Eodiscina from the Oslo Region, Norway. Palaeontographica A286, 1–87.

External links

"Ptychagnostus praecurrens". Burgess Shale Fossil Gallery. Virtual Museum of Canada. 2011. Archived from the original on 2020-11-12. Retrieved 2023-01-21.
Media related to Ptychagnostus at Wikimedia Commons

This Agnostida-related article is a stub. You can help Wikipedia by expanding it.

[gon-1] Samuel M. Gon III. "Agnostida Fact Sheet". A Guide to the Orders of Trilobites. Retrieved 18 November 2012.

[2] Brian D. E. Chatterton, Desmond H. Collins & Rolf Ludvigsen (2003). "Cryptic behaviour in trilobites: Cambrian and Silurian examples from Canada, and other related occurrences". In Philip D. Lane, Derek J. Siveter & Richard A. Fortey (ed.). Trilobites and their Relatives: contributions from the third international conference, Oxford 2001. Special Papers in Palaeontology. Vol. 70. pp. 157–173. ISBN 978-0-901702-81-4.

[3] Coppold, Murray and Wayne Powell (2006). A Geoscience Guide to the Burgess Shale, p.56. The Burgess Shale Geoscience Foundation, Field, British Columbia. ISBN 0-9780132-0-4.

[4] BRØGGER W. C. 1878. Om paradoxides-skifrene ved Krekling. Nyt Magazin for Naturvidens-kaberne 24, 18–88.

[5] LAURIE J. R. 2008. Species relationships in the Ptychagnostidae (Cambrian, Agnostina). In: Ra´bano I., Gozalo R. & GarciaBellido D. eds. Advances in trilobite research, pp. 211–218. Cuadernos del Museo Geominero 9.

[6] HØYBERGET M. & BRUTON D. L. 2008. Middle Cambrian trilobites of the suborders Agnostina and Eodiscina from the Oslo Region, Norway. Palaeontographica A286, 1–87.

[1]

[2]

[3]

[4]

[5]

[6]