Dikelocephaloidea

Cephalon and pygidium of Lorrettina depressa, from Shergold (1980).

Belongs within: Asaphida.

The Dikelocephalacea are a group of medium-sized to large trilobites from the Cambrian period (Harrington et al. 1959).

Characters (from Harrington et al. 1959): Exoskeleton opisthoparian, medium-sized to large, ellipsoidal in outline, heteropygous to subisopygous. Cephalon mostly semicircular, with more or less broadly tapering glabella bearing two or three pairs of lateral glabellar furrows, posterior areas commonly complete; frontal area transversely and sagittally broad, anterior border furrow shallow to obsolete; palpebral lobes prominent, eyes usually medium-sized; librigenae bearing medium to long genal spine. Thorax with thirteen or fewer segments. Pygidium broadly ovate to transverse, with interpleural and pleural furrows tending to curve conspicuously backward across broad border, some forms with pair of short posterolateral spines. Surface smooth to finely granulose.

Dikelocephaloidea [Dikelocephalacea]
|--DikelocephalusF71 [DikelocephalidaeRC93]
| `--D. florentinensis Etheridge 1904F71
|--EurekiaLM05 [EurekiidaeRC93]
| |--E. apopsisLM05
| `--E. eosLM05
|--PtychaspisCT83 [PtychaspididaeRC93]
| |--P. cetoCT83
| |--P. sphairaCT83
| `--P. subglobosaCT83
`--SaukiidaeJB12
|--SaukiaF90
| |--S. acamusCT83
| `--S. aojiiCT83
`--Prosaukia Ulrich & Resser 1933S80
|--*P. misa (Hall 1863) [=Dikelocephalus misa]S80
|--P. brizoCT83
|--P. orientalisCT83
`--P. ulrichiCT83

Dikelocephaloidea incertae sedis:
AtratebiinaeS80
|--Atratebia Shergold 1975S80
| `--A. nexosa Shergold 1975S80
|--Mendosina Shergold 1975S80
| `--M. laciniosa Shergold 1972S80
`--Taishania Sun 1935S80
|--*T. taianensis Sun 1935 [=Mansuyia endoi Resser 1942]S80
|--‘Mansuyia’ maladiformis Kobayashi 1935S80
|--‘Anomocare’ persicum King 1930S80
|--T. platyfrons Shergold 1980S80
`--‘Elrathia’ yentaiensis Endo 1944S80
BriscoiaS80
|--B. harttiS80
`--B. septentrionalisS80
Tellerina paichiaensisS80, CT83

*Type species of generic name indicated

References

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

[F71] Fletcher, H. O. 1971. Catalogue of type specimens of fossils in the Australian Museum, Sydney. Australian Museum Memoir 13: 1–167.

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

Harrington, H. J., G. Henningsmoen et al. 1959. Systematic descriptions. In Treatise on Invertebrate Paleontology pt O. Arthropoda 1 pp. O170–O540. Geological Society of America and University of Kansas Press.

[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.

[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.

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