Temporal range: Ediacaran, around 558–550 Ma Ediacaran
|Phylum:||Trilobozoa Fedonkin, 1985
[nom. transl. Runnegar, 1992 ex
Class Trilobozoa Fedonkin, 1985]
|Family and Genera|
Trilobozoa ("three-lobed animals") is a taxon of extinct organisms which displayed tri-radial symmetry. Fossils of trilobozoans are restricted to marine strata of the Late Ediacaran period — prior to the Cambrian explosion of more modern life forms.
The taxonomic affinities of this groups are open to debate. Ivantsov and Fedonkin (2002) place them among the cnidarians. They reasoned that since the conulate Vendoconularia exhibited six-fold symmetry, the conularids — then regarded as a sister group to the scyphozoan cnidarians — must be nested within the trilobozoa, making the trilobozoan group part of the cnidarian phylum.
Most trilobozoans were disk-shaped, typified by Tribrachidium. Through comparisons with the other discoidal trilobozoans, it appears the different "arm" patterns on each genus/species occurred due to growth arresting or progressing at different stages of developmental growth.
The various members of Trilobozoa are organized into (monotypic) genera, and some are grouped into families.
Family Albumaresidae Fedonkin, 1985
- Albumares Fedonkin, 1976, Suz'ma, White Sea locality; Reaphook Hill of Flinders Range
- Anfesta Fedonkin, 1984, Zimnii Bereg and Kharakta River, White Sea locality; Flinders Range
Family Tribrachididae Runnegar, 1992
- Tribrachidium Glaessner, 1959 Flinders Range; Dniester River Basin, Podolia, Ukraine; Suz'ma and Solza rivers, White Sea locality
Trilobozoa incertae sedis
The following genera are triradially symmetric edicarans that have not yet been classified into either Albumaresidae or Tribrachididae, nor a new family.
- Skinnera Wade, 1969, Mount Skinner; Flinders Range
- Hallidaya Wade, 1969, Mount Skinner
- ?Triforillonia Gehling et al., 2000, Mistaken Point
- ?Rugoconites Glaessner et Wade, 1966, Flinders Range
- Ivantsov, Andrei Yu.; Fedonkin, Mikhail A. (2002). "Conulariid-like fossil from the Vendian of Russia: A metazoan clade across the Proterozoic/Palaeozoic boundary". Palaeontology. 45 (6): 1219–1229. doi:10.1111/1475-4983.00283.
- Fedonkin, Mikhail A. (2007). The Rise of Animals: Evolution and Diversification of the Kingdom Animalia. JHU Press. ISBN 9780801886799.
- McMenamin, M.A.S (1998). The Garden of Ediacara. New York: Columbia University Press. ISBN 0-231-10559-2.
- Dzik, Jerzy (2003). "Anatomical Information Content in the Ediacaran Fossils and Their Possible Zoological Affinities". Integrative and Comparative Biology. 43 (1): 114–126. PMID 21680416. doi:10.1093/icb/43.1.114.
- Ediacara Assemblage University of Bristol