Trilobozoa

Paraconularia missouriensis, from here.

Belongs within: Coelenterata.
Contains: Anabaritida, Conulata.

The Trilobozoa are a group of organisms of uncertain relationships known from the Ediacaran and lower Cambrian, characterised by the presence of three planes of symmetry or by the spiral rotation of three independent arm-like structures (Erwin et al. 2011). These include the Ediacaran Triradialomorpha, which were benthic, reclining forms of a superficially medusoid appearance.

Ivantsov & Fedonkin (2002) also suggested that the Conulariida, a group of sessile, pyramidal animals that survived to the Triassic, may be descended from the Trilobozoa. Conulariids possessed an external test supported by transverse rods of calcium phosphate. Though the majority of later conulariids have a fourfold symmetry in the manner of modern Scyphozoa, the Ediacaran Vendoconularia triradiata has a similar (albeit non-mineralised) test but with six faces.

<==Trilobozoa
    |--+--Hallidaya Wade 1969IF02, G79
    |  |    `--*H. brueri Wade 1969G79
    |  `--+--AnabaritidaIF02
    |     `--ConulataIF02
    `--Tribrachiomorpha [Triradialomorpha]G14
         |  i. s.: Triforillonia costellae Gehling et al. 2000G14
         |         Skinnera Wade 1969EL11, G79
         |           `--*S. brooksi Wade 1969G79
         |         Tribrachidium Glaessner in Glaessner & Daily 1959EL11, G79
         |           `--*T. heraldicum Glaessner in Glaessner & Daily 1959G79
         |--Pomoria [Pomoriidae]EL11
         |    `--P. corolliformis Fedonkin 1980NS93
         `--AlbumaresidaeWS93
              |--Anfesta stankovskii Fedonkin 1984WS93
              `--Albumares Fedonkin in Keller & Fedonkin 1976IF02, G79
                   `--*A. brunsae Fedonkin in Keller & Fedonkin 1976G79

*Type species of generic name indicated

References

[EL11] Erwin, D. H., M. Laflamme, S. M. Tweedt, E. A. Sperling, D. Pisani & K. J. Peterson. 2011. The Cambrian conundrum: early divergence and later ecological success in the early history of animals. Science 334: 1091–1097.

[G79] Glaessner, M. F. 1979. Precambrian. In: Robison, R. A., & C. Teichert (eds) Treatise on Invertebrate Paleontology pt A. Introduction. Fossilisation (Taphonomy), Biogeography and Biostratigraphy pp. A79–A118. The Geological Society of America, Inc.: Boulder (Colorado), and The University of Kansas: Lawrence (Kansas).

[G14] Grazhdankin, D. 2014. Patterns of evolution of the Ediacaran soft-bodied biota. Journal of Paleontology 88 (2): 269–283.

[IF02] Ivantsov, A. Yu., & M. A. Fedonkin. 2002. Conulariid-like fossil from the Vendian of Russia: a metazoan clade across the Proterozoic/Palaeozoic boundary. Palaeontology 45 (6): 1219–1229.

[WS93] Wills, M. A., & J. J. Sepkoski Jr. 1993. Problematica. In: Benton, M. J. (ed.) The Fossil Record 2 pp. 543–554. Chapman & Hall: London.

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