Bumastus ioxus, copyright American Museum of Natural History.

Belongs within: Trilobita.
Contains: Onchonotellus, Ptychoparioidea, Ellipsocephaloidea, Asaphida, Phacopida, Olenacea, Harpina, Proetida.

The Ptychopariida have been recognised as a group of trilobites known from the Middle Cambrian to the Late Ordovician. However, this group is probably paraphyletic, with a number of later trilobite groups, some surviving into the Devonian, derived from within the ptychopariidans (Prothero 1998).

<==Libristoma [Ptychopariida]F90
    |    |--PtychoparioideaP98
    |    `--EllipsocephaloideaRC93
    |  `--PhacopidaF90
Libristoma incertae sedis:
    |--Onchonotina Lu 1961S80
    |    `--O. vigilansCT83
    `--Onchonotus Raymond 1924S80
    |--T. megalops Kobayashi 1938S80
    `--T. polyaricus Rosova 1963S80
  Guizhoucephalina Chien 1961S80
    `--*G. longispina Chien 1961S80
  Catillicephalidae [Catillicephalacea]SS84
    |--Pseudopetigurus Prantl & Přibyl 1950SS84
    `--Parahystricurus Ross 1951SS84
         `--P. oculirotundus Ross 1951F90
    |--Elrathia kingiP98
         |--*D. nitida (Hall & Whitfield 1877)S80
         |--D. bigranulosa Palmer 1960S80
         |--D. brevispina Palmer 1965S80
         `--D. simplex Rasetti 1961S80
  Koldinia Walcott & Resser 1924SS84
  Wanwanaspis Kobayashi 1966SS84
  Wanwanoglobus Kobayashi 1966SS84
  Koldiniella Lermontova 1940SS84
    `--K. mitellaSS84
    |--Plethopeltis arbucklensisLM05
    |--Stenopilus latusSS84, LM05
    |--Leiocoryphe transversa Rasetti 1945SS84
    `--Plethometopus [Plethometopidae]SS84
         `--P. obtususLM05
  Genevieviella neunia Lochman 1936SS84
  Raashellina paula Rozova 1963SS84
    |--B. coraxS80
    `--B. tetragonalisF90
         |--B. t. tetragonalisF90
         `--B. t. broeggeriF90
  Ehmaniella waptaensisF90
  Kirengina Ogienko 1974F90

*Type species of generic name indicated


[CT83] Chen J.-Y. & C. Teichert. 1983. Cambrian Cephalopoda of China. Palaeontographica Abteilung A: Paläozoologie—Stratigraphie 181 (1–3): 1–102.

[F90] Fortey, R. A. 1990. Ontogeny, hypostome attachment and trilobite classification. Palaeontology 33 (3): 529–576.

[JB12] Johnson, M. E., & B. G. Baarli. 2012. Development of intertidal biotas through Phanerozoic time. In: Talent, J. A. (ed.) Earth and Life: Global biodiversity, extinction intervals and biogeographic perturbations through time pp. 63–128. Springer.

[LM05] Lehnert, O., J. F. Miller, S. A. Leslie, J. E. Repetski & R. L. Ethington. 2005. Cambro-Ordovician sea-level fluctuations and sequence boundaries: the missing record and the evolution of new taxa. Special Papers in Palaeontology 73: 117–134.

[P98] Prothero, D. R. 1998. Bringing Fossils to Life: An introduction to paleobiology. WCB McGraw-Hill: Boston.

[RC93] Romano, M., W. T. Chang, W. T. Dean, G. D. Edgecombe, R. A. Fortey, D. J. Holloway, P. D. Lane, A. W. Owen, R. M. Owens, A. R. Palmer, A. W. A. Rushton, J. H. Shergold, D. J. Siveter & M. A. Whyte. 1993. Arthropoda (Trilobita). In: Benton, M. J. (ed.) The Fossil Record 2 pp. 279–296. Chapman & Hall: London.

[S80] Shergold, J. H. 1980. Late Cambrian trilobites from the Chatsworth Limestone, western Queensland. Bureau of Mineral Resources, Geology and Geophysics—Bulletin 186: 1–111.

[SS84] Shergold, J. H., & K. Sdzuy. 1984. Cambrian and early Tremadocian trilobites from Sultan Dağ, central Turkey. Senckenbergiana Lethaea 65 (1–3): 51–135.

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