Triangulata

Belongs within: Aculearia.

The Triangulata are a group of radiolarians, known from the Middle Ordovician to the Permian, in which the skeleton is built around a central triangular frame (Afanasieva et al. 2005).

Characters (from Afanasieva et al. 2005): Bilaterally symmetrical skeleton composed of three intersecting main spines forming an internal triangular frame. Main triangular frame of skeleton formed by fusion of two initial four-rayed spicules and by development of spines that form it (a, b, i) in one plane.

<==TriangulataAA05
    |--RaphidociclicidaeAA05
    |    |--Protoceratoikiscum Goto, Umeda & Ishiga 1992AA05
    |    |--Raphidociclicus Nazarov & Rudenko 1981AA05
    |    |    `--R. hiulcusAA05
    |    `--Helenifore Nazarov & Ormiston 1983AA05
    |         `--H. laticlavumAA05
    `--+--CeratoikiscidaeAA05
       |    |--Glanta Wakamatsu, Sugiyama & Furutani 1990AA05
       |    |--Nazaromistonella Furutani 1990AA05
       |    |--Circulaforma Cheng 1986AA05
       |    |    `--C. delicataAA05
       |    `--Ceratoikiscum Deflandre 1953AA05
       |         |--C. bujugumAA05
       |         |--C. ukhtensisAA05
       |         `--C. vimenumAA05
       `--LapidopiscidaeAA05
            |--Huasha Cheng 1986AA05
            |--Protoholoeciscus Aitchison 1993AA05
            |--Lapidopiscum Deflandre 1958AA05
            |    `--L. pivetauiAA05
            |--Neoholoeciscus Ormiston & Lane 1976AA05
            |    `--N. cancermimusAA05
            `--Holoeciscus Foreman 1963AA05
                 |--H. aucepsAA05
                 `--H. foremanaeAA05

*Type species of generic name indicated

References

[AA05] Afanasieva, M. S., E. O. Amon, Y. V. Agarkov & D. S. Boltovskoy. 2005. Radiolarians in the geological record. Paleontological Journal 39 (Suppl. 3): S135–S392.