Schematic drawings of Loculitheca kunka, from Kruse (2002).

Belongs within: Hyolitha.

The Circothecida are a group of hyoliths in which the dorsum and venter are undifferentiated or weakly differentiated (Kruse 2002).

    |  i. s.: Conotheca Missarzhevksy in Rozanov et al. 1969D94, KB09
    |           |--C. australiensis Bengtson in Bengtson et al. 1990K02
    |           |--C. circumflexa Missarzhevksy in Rozanov et al. 1969KB09
    |           `--C. laurentiensis Landing & Bartowski 1996CA06
    |--Spinulitheca Syssoiev 1968D78 [Extentithecidae, SpinulithecidaeK02]
    |    |--S. billingsi (Sysoiev 1962)D94
    |    `--S. kuteinikovi (Missarzhevsky 1969)W93
    |    |--Loculitheca Sysoyev 1968K02
    |    |    |--*L. anulata (Sysoyev 1959) [=Circotheca anulata]K02
    |    |    `--L. kunka Kruse 2002K02
    |    `--Turcutheca Missarzhevsky 1969D78
    |         |--T. bitubaK02
    |         |--T. cotuiensis (Sysoiev 1959)W93
    |         |--T. crasseocochlia Syssoiev 1962D94
    |         `--T. cylindricaK02
         |--Crossbitheca Missarzhevsky 1974W93, D78
         |    `--C. arcuaria Missarzhevsky 1974W93
         |--Laratheca Missarzhevsky 1969W93, D78
         |    `--L. nana Missarzhevsky 1969W93
         |--Guduguwan Kruse 1990K02
         |    `--*G. hardmani (Etheridge in Foord 1890) [=Salterella hardmani, Biconulites hardmani]K02
         |--Larawa [Larawidae]K02
         |    `--L. djanin Kruse 1990K02
         `--Circotheca Syssoiev 1958F62
              |--*C. stylus (Holm 1893) [=Hyolithus stylus, Orthotheca stylus]MB-M99
              |--C. kuteinikovi Missarzhevsky 1969W93
              `--C. longiconica Qian 1978W93

*Type species of generic name indicated


[CA06] Clausen, S., & J. J. Álvaro. 2006. Skeletonized microfossils from the Lower–Middle Cambrian transition of the Cantabrian Mountains, northern Spain. Acta Palaeontologica Polonica 51 (2): 223–238.

[D78] Durham, J. W. 1978. The probable metazoan biota of the Precambrian as indicated by the subsequent record. Ann. Rev. Earth Planet Sci. 6: 21–42.

[D94] Dzik, J. 1994. Evolution of ‘small shelly fossils’ assemblages of the early Paleozoic. Acta Palaeontologica Polonica 39 (3): 247–313.

[F62] Fisher, D. W. 1962. Small conoidal shells of uncertain affinities. In: Moore, R. C. (ed.) Treatise on Invertebrate Paleontology pt W. Miscellanea: Conodonts, Conoidal Shells of Uncertain Affinities, Worms, Trace Fossils and Problematica pp. W98–W143. Geological Society of America, and University of Kansas Press.

[KB09] Kouchinsky, A., S. Bengtson, W. Feng, R. Kutygin & A. Val’kov. 2009. The Lower Cambrian fossil anabaritids: affinities, occurrences and systematics. Journal of Systematic Palaeontology 7 (3): 241–298.

[K02] Kruse, P. D. 2002. Biostratigraphic potential of Middle Cambrian hyoliths from the eastern Georgina Basin. Alcheringa 26: 353–398.

[MB-M99] Malinky, J. M., & V. Berg-Madsen. 1999. A revision of Holm’s Early and early Mid Cambrian hyoliths of Sweden. Palaeontology 42: 25–65.

[W93] Wills, M. A. 1993. ?Mollusca incertae sedis. In: Benton, M. J. (ed.) The Fossil Record 2 pp. 265–270. Chapman & Hall: London.

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