Trilobozoa
| Trilobozoa | ||||||||
|---|---|---|---|---|---|---|---|---|
Tribrachidium (above) and other, different Trilobozoa |
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| Temporal occurrence | ||||||||
| Ediacarium | ||||||||
| 558 to 550 million years | ||||||||
| Locations | ||||||||
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| Systematics | ||||||||
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| Scientific name | ||||||||
| Trilobozoa | ||||||||
| Fedonkin , 1985 | ||||||||
| Genera | ||||||||
The Trilobozoa are an extinct tribe of the animal kingdom , which is characterized by tri-radial symmetry and which was widespread even before the Cambrian Explosion in the late Ediacarian .
etymology
The name Trilobozoa (three-prized animals) is a word created from the three ancient Greek words τρι tri 'three', λοβός lobós 'lobes / bulge' and ζῷον zóon 'animal'.
Taxonomy
The family relationships of the Trilobozoa are still not clear. Ivantsov and Fedonkin (2002) classify the strain under the cnidarians (Cnidaria). They base this conclusion on the order of Conulariida belonging Vendoconularia that suggest a hexagonal symmetry of the day and were asked taxonomically to the trilobozoa. Since the Conulariida are a sister group of the umbrella jellyfish (Scyphozoa), according to Ivantsov and Fedonkin, the Trilobozoa must also belong to the tribe of Cnidaria.
Trilobozoa, however, only resemble cnidarians superficially. They were initially still regarded as a class of the Coelenterata tribe, but after the Coelenterata was split into the two separate tribes Cnidaria and Ctenophora, the Trilobozoa were finally also raised to the rank of a tribe.
description
The most primitive Trilobozoa, represented by Tribrachidium , were disk-like organisms. Comparisons with other discus-like Trilobozoa showed that the different arm patterns of the individual taxa were caused by growth (through growth stop or renewed growth) and corresponded to different stages of development.
More advanced and long-standing Trilobozoa, such as the long-lived taxon Conularia , had the shape of an elongated cone. Their shell structures resemble square ice cream cones. The lack of septa or other diagnostic structures for flower animals (anthozoa), however, caused many investigators to move away from an origin of the conularids from anthozoa (Conularidae are usually not counted among the Ediacara biota , since they only started shortly before the beginning of the Cambrian in the fossil record and survived into the Lower Triassic ).
Ivantsov and Fedonkin are of the opinion that the Conularida originally had triradial symmetry. They advocate the following evolutionary scheme:
Albumares and Tribrachidium → Anfesta and Rugoconites → Hallydaya → Anabaritidae → Carinachitiida and Hexanguloconularida
In the meantime, the conviction seems to be gaining ground that the four-sided symmetry of conulate Trilobozoa emerged from a six-sided symmetry that existed in Vendoconularia. The latter, in turn, had developed from the triple symmetry of their disc-shaped trilobozoa ancestors.
Taxonomy
The Trilobozoa are divided into monotypical taxa, which form two families:
Family Albumaresidae Fedonkin, 1985
- Albumares Fedonkin, 1976
Occurrence on the Sjusma on the White Sea and on Reaphook Hill in the Flinders Range
- Anfesta Fedonkin, 1984
Simni Bereg and on the character (White Sea coast), as well as in the Flinders range
Family Tribrachididae Runnegar, 1992
- Tribrachidium Glaessner, 1959
Occurrence in the Flinders range, in the Dniester basin in Podolia ( Ukraine ) and on the Sjusma and Solsa on the White Sea coast
Trilobozoa incertae sedis
The following taxa have an unsafe position and are not assigned to any family:
- Skinnera Wade, 1969 - Mount Skinner , Flinders Range
- Hallidaya Wade, 1969 - Mount Skinner, Flinders Range
- ? Triforillonia Gehling et al., 2000 - Mistaken Point , Newfoundland
- ? Rugoconites Glaessner and Wade, 1966 - Flinderskette
Family Anabaritidae
Ivantsov and Fedonkin (2002) also include the Early Cambrian Angustiochreida (or Anabaritidae) and related taxa among the Trilobozoa.
Individual evidence
- ↑ Fedonkin, MA: Precambrian Metazoans . Eds .: Briggs, D. and Crowther, P. Palaeobiology: A Synthesis. Blackwell, 1990, pp. 17-24 .
- ↑ Runnegar, BN and Fedonkin, M.A.: Proterozoic Metazoan Body Fossils . Ed .: Schopf, JW and Klein, C. The Proterozoic Biosphere: A Multidisciplinary Study. Cambridge University Press, 1992, pp. 373 .
- ^ A b Ivantsov, AJ and Fedonkin, MA: Conulariid-like fossil from the Vendian of Russia: A Metazoan clade across the Proterozoic / Palaeozoic boundary . In: Palaeontology . tape 45 , 2002, p. 1219-1229 .