Ptychagnostus

Ptychagnostus is an extinct genus of blind trilobite that lived during the Cambrian period, part of the order Agnostida. Ptychagnostidae generally do not exceed ten millimetres in length.[1] Their remains are sometimes found in the otherwise empty tubes of the polychaete worm Selkirkia.[2] It probably lived in the water column. Its major characteristics are lack of eyes, two lobes on the glabella, and three lobes on the pygidium.[3]

Ptychagnostus
Temporal range: Middle Cambrian
Ptychagnostus germanus
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: †Trilobita
Order: †Agnostida
Family: †Ptychagnostidae
Genus: †Ptychagnostus
Jaekel, 1909
Synonyms[1]
  • 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

Species
  • Ptychagnostus aculeatus
  • Ptychagnostus akanthodes
  • Ptychagnostus atavus
  • Ptychagnostus cassis
  • Ptychagnostus ciceroides
  • Ptychagnostus cuyanus
  • Ptychagnostus fissus
  • Ptychagnostus germanus
  • Ptychagnostus gibbus
  • Ptychagnostus hybridus
  • Ptychagnostus intermedius
  • Ptychagnostus michaeli
  • Ptychagnostus praecurrens
  • Ptychagnostus punctuosus
  • Ptychagnostus seminula
gollark: It's a type of monoid.
gollark: The bees do not say anything about this "homestuck adaptation".
gollark: You should all do this, it's great.
gollark: https://media.discordapp.net/attachments/426116061415342080/899376149518508113/image0.png?width=448&height=623
gollark: As far as I know, as well as developmental differences, you would have different DNA due to different random selection from the pairs of genes you have now.

References
  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. 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.


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