Trilobozoa
Trilobozoa | |
---|---|
The many members of the Trilobozoa. (clockwise from top): Tribrachidium, Rugoconites enigmaticus, R. tenuirugosus Albumares brunsae, Hallidaya brueri, Anfesta stankovskii, Lorenzinites rarus, Wigwamiella enigmatica and Skinerra brooksi. | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Subkingdom: | Eumetazoa |
Phylum: | †Trilobozoa Fedonkin, 1985 [nom. transl. Runnegar, 1992 ex Class Trilobozoa Fedonkin, 1985] |
Genera | |
For minor descriptions, see text | |
Synonyms | |
|
Trilobozoa (meaning "three-lobed animals") is a phylum of extinct, sessile animals that were originally classified into the Cnidaria. The basic body plan of trilobozoans is often a tri-radial or radial sphere-shaped form with lobes radiating from its centre. [1] Fossils of trilobozoans are restricted to marine strata of the Late Ediacaran period.
History and interpretations
Originally, both
Most of the members of what is now the modern day classification for Trilobozoa were thought to have originally been free swimming
The members of the Trilobozoa are now thought to be sessile,
Description
Trilobozoans had a tri-radial shield-like body that had three antimeres which consisted of a cluster of grooves on their outer surface and within their inner cavity.[1] Most of the members of the Trilobozoa possessed bifurcating concave areas internally that were all separated by sharp ridges.[6] These structures were more likely stiff and culticular rather than elastic internal bodies or membranes[6] even though those structures may have been resistant, they also could've corresponded to collapsed chambers that can be observed within the related genera Albumares and Anfesta. In Tribrachidium, the sediment preserving the animal penetrated from above only within areas between those organs. The spiral-like orientation of the internal bodies of trilobozoans suggests that they were modified from an originally longitudinal to the axis which resulted in the deposition of the organs.[6]
Albumares
Albumares brunsae represents a form first described from the White Sea of Russia by Mikhail A. Fedonkin in 1976.[2] In life, Albumares most likely had an umbrella-like shape with tri-radial symmetry along with three ridges radiating from its centre. Fossils of Albumares are known from Russia and South Australia and preserve 100 small (0.15 millimeters (0.0059 in) each) marginal tentacles. From the centre of the lobes arise three canals that split at least 4 times across the body.[2] The then split canals then split until they reach the outer margin of the body. The diameter of the body is 13 millimeters (0.51 in), the length of the lobes are 5 millimeters (0.20 in) maximum.[2] Albumares is similar and may be a close relative of the Anfesta
Anfesta
Anfesta stankovskii represents a small (18 millimeters (0.71 in) hemispherical-shaped form with flattened, three-fold symmetry.[2] Similarly to Albumares, three long sausage-shaped lobes radiate from its centre that are all separated by an angle of 120 degrees. The lobes taper at both their proximal and distal ends, which divide the organism into a number of narrow bodies that are divisible by three. Some specimens from both Australia and Russia preserve tentacles (canals) similar to that of Albumares.[2] Unlike Albumares and Skinnera, Anfesta is more oval-shaped and discoidal rather than being dominantly tri-lobate. The length of the lobes is 5 millimeters (0.20 in) with the width being up to 1.3 millimeters (0.051 in).[2]
Hallidaya
Hallidaya brueri constitutes as a discoidal form that is restricted to
Rugoconites
Rugoconites is a genus of oval- circular-shaped preserved in high relief about six or more centimetres in diameter. The shape of Rugoconites is different in both of its species; R. enigmaticus Glaessner & Wade 1966 is more dome shaped and R. tenuirugosus Wade 1972 is flatter although bigger.
Skinerra
Skinnera brooksi defines small discoidal fossils preserved as composite moulds on sandstone.[7] Fossils are characterized by three radially arranged pouch-shaped depressions that are interpreted as a stomach similar to that seen in Hallidaya. These depressions are then connected to an outer rim by approximately 15 smaller pouches along the disk by canals.[7] S. brooksi fossils range from 3.9 millimeters (0.15 in) to 32 millimeters (1.3 in) and are slightly domed by being 2 millimeters (0.079 in) tall. Skinnera and Hallidaya are considered to be close relatives.[7]
Tribrachidium
Tribrachidium heraldicum is a small (3 to 40 millimetres)[11] tri-radially symmetrical form often preserved on the base of sandstones and often show a three-lobed, circular animal preserved in it.[12] The central part of T. heraldicum has three hooked ridges (or arms) that make up the lobes; the arms are covered by numerous branched furrows that were interpreted as tentacles.[12][13]
See also
References
- ^ S2CID 245330736.
- ^ ISBN 9780801886799. Retrieved 1 July 2022 – via Google Books.
- ^ S2CID 128620276.
- ISBN 978-0-19-856620-5.
- ISBN 9780521366151.
- ^ PMID 21680416.
- ^ a b c d e f Wade, M (1969). "Medusae from uppermost Precambrian or Cambrian sandstones, central Australia". Palaeontology. 12: 351–365.
- ^ "Rugoconites". Ediacaran.org.
- S2CID 84598490.
- S2CID 130802211.
- ^ "Tribrachidium".
- ^ a b Ivantsov, Andrey (January 2008). "The imprints of Vendian animals - unique paleontological objects of the Arkhangelsk region".
- ^ Glaessner, M.F.; Wade, M. (1966). "The late Precambrian fossils from Ediacara, South Australia" (PDF). Palaeontology. 9 (4): 599. Archived from the original (PDF) on 2013-09-22. Retrieved 2023-01-13.
External links
- Ediacara Assemblage University of Bristol