Olenacea

Olenus gibbosus, from here.

Belongs within: Ptychopariida.

The Olenacea are a group of trilobites known from the Middle Cambrian to the Upper Ordovician (Harrington et al. 1959).

Characters (from Harrington et al. 1959): Exoskeleton subovate to elongate, opisthoparian (exceptionally proparian), micropygous to (rarely)subisopygous, with rounded or spinose genal angles. Cephalon with narrow border, small to medium-sized eyes and in most forms distinct eye ridges; glabella tapering forward, with simple, sigmoidal, or bifurcate lateral furrows (if present); preglabellar field present or absent; librigenae separated by median suture or fused together. Hypostoma probably free. Thorax with 9 to 24 segments. Pygidium with or without marginal spines.

<==Olenacea
    |--Elviniinae [Elviniidae] S80
    |    |--Wentsuia Sun 1935 S80
    |    |    |--*W. granulosa Sun 1935 S80
    |    |    |--W. iota Shergold 1980 S80
    |    |    `--‘Elrathia’ munda Resser & Endo in Endo & Resser 1937 S80
    |    `--Dunderbergia S80
    |         |--*D. nitida (Hall & Whitfield 1877) S80
    |         |--D. bigranulosa Palmer 1960 S80
    |         |--D. brevispina Palmer 1965 S80
    |         `--D. simplex Rasetti 1961 S80
    |--Pterocephaliidae S80
    |    |--Pterocephaliinae S80
    |    |    |--Sigmocheilus S80
    |    |    `--Pterocephalia S80
    |    |--Changshaniinae S80
    |    |    |--Changshania conica S80
    |    |    `--Parachangshania Chien 1958 S80
    |    |         `--‘Maladioidella’ elongata Endo 1944 S80
    |    `--Eugonocare Whitehouse 1939 [Aphelaspidinae] S80
    |         |--*E. tessellatum Whitehouse 1939 S80
    |         |--E. quadratum Henderson 1976 S80
    |         `--E. whitehousei Henderson 1976 S80
    `--Olenidae S80
         |  i. s.: Hedinia regalis Troedsson 1937 S80
         |         Porterfieldia punctata FO99
         |         Peltura scarabaeoides FO99
         |--Leptoplastus Angelin 1854 [Leptoplastinae] S80
         |    |--*L. stenotus Angelin 1854 S80
         |    `--L. rhaphidophorus Angelin 1854 S80
         `--Oleninae S80
              |--Plicatolina Shaw 1951 S80
              |    |--*P. kindlei Shaw 1951 S80
              |    |--P. lucida Lazarenko 1966 S80
              |    |--P. perlata lazarenko 1966 S80
              |    |--P. quadrata Pokrovskaya 1966 S80
              |    |--P. scalpta Harrington & Leanza 1957 S80
              |    `--P. yakutica Pokrovskaya 1966 S80
              `--Olenus LN05
                   |--O. attenuatus (Boeck 1838) LN05
                   |--O. dentatus (Westergård 1922) LN05
                   |--O. gibbosus (Wahlenberg 1821) LN05
                   `--+--O. transversus LN05
                      `--+--O. truncatus (Brünnich 1781) LN05
                         `--O. wahlenbergi (Wahlenberg 1821) LN05

*Type species of generic name indicated

REFERENCES

[FO99] Fortey, R. A. & R. M. Owens. 1999. Feeding habits in trilobites. Palaeontology 42 (3): 429–465.

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.

[LN05] Lauridsen, B. W., & A. T. Nielsen. 2005. The Upper Cambrian trilobite Olenus at Andrarum, Sweden: a case of iterative evolution? Palaeontology 48 (5): 1041–1056.

[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.