Namacalathus[a] is a problematic metazoan fossil occurring in the latest Ediacaran. The first, and only described species, N. hermanastes,[b] was first described in 2000 from the Nama Group of central and southern Namibia.[1]
A U–Pb zircon age from the fossiliferous rock in Namibia and Oman provides an age for the Namacalathus zone in the range from 549 to 542 Ma, which corresponds to the Late Ediacaran.
Alongside Namapoikia and Cloudina, these organisms are the oldest known evidence in the fossil record of the emergence of calcified skeletal formation in metazoans, a prominent feature in animals appearing later in the Early Cambrian. Shore et al. (2021) reported the first three-dimensional, pyritized preservation of soft tissue in Namacalathus hermanastes from the Nama Group (Namibia), and evaluate the implications of this finding for the knowledge of the phylogenetic relationships of this animal; they suggest it is an ancestor of Lophotrochozoan animals such as brachiopods and worms.[2]
There are only five occurrences of Namacalathus (Namibia, Canada, Oman, Siberia, Paraguay) known to date, all of which are found in association with Cloudina fossils.[1][3][4][5][6][7]
Among the late Precambrian fossil assemblage in the Nama group, Namibia, Namacalathus far outnumber Cloudina and other poorly preserved taxa and ichnofossils found in the formation. The Nama Group fossils occur within thrombolitic facies of immense Proterozoic stromatolitic reefs. Namacalathus lived a benthic existence with its stalk attached to the sea floor by means of a holdfast, or possibly to algal mats growing on the reef surface.
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^ abGrotzinger, John P.; Watters, Wesley A.; Knoll, Andrew H. (2000). "Calcified metazoans in thrombolite-stromatolite reefs of the terminal Proterozoic Nama Group, Namibia". Paleobiology. 26 (3): 334–359. doi:10.1666/0094-8373(2000)026<0334:CMITSR>2.0.CO;2. S2CID 52231115.
^Shore, A. J.; Wood, R. A.; Butler, I. B.; Zhuravlev, A. Yu.; McMahon, S.; Curtis, A.; Bowyer, F. T. (2021). "Ediacaran metazoan reveals lophotrochozoan affinity and deepens root of Cambrian Explosion". Science Advances. 7 (1): eabf2933. Bibcode:2021SciA....7.2933S. doi:10.1126/sciadv.abf2933. PMC 7775780. PMID 33523867.
^Amthor, Joachim E.; Grotzinger, John P.; Schröder, Stefan; Bowring, Samuel A.; Ramezani, Jahandar; Martin, Mark W.; Matter, Albert (2003). "Extinction of Cloudina and Namacalathus at the Precambrian-Cambrian boundary in Oman". Geology. 31 (5): 431–434. Bibcode:2003Geo....31..431A. doi:10.1130/0091-7613(2003)031<0431:EOCANA>2.0.CO;2.
^Hofmann, Hans J.; Mountjoy, Eric W. (2001). "Namacalathus-Cloudina assemblage in Neoproterozoic Miette Group (Byng Formation), British Columbia: Canada's oldest shelly fossils". Geology. 29 (12): 1091–1094. Bibcode:2001Geo....29.1091H. doi:10.1130/0091-7613(2001)029<1091:NCAINM>2.0.CO;2.
^Kontorovich, A.E.; Varlamov, A.I.; Grazhdankin, D.V.; Karlova, G.A.; Klets, A.G.; Kontorovich, V.A.; Saraev, S.V.; Terleev, A.A.; Belyaev, S.Yu.; Varaksina, I.V.; Efimov, A.S.; Kochnev, B.B.; Nagovitsin, K.E.; Postnikov, A.A.; Filippov, Yu.F. (2008). "A section of Vendian in the east of West Siberian Plate (based on data from the Borehole Vostok 3)". Russian Geology and Geophysics. 49 (12): 932–939. Bibcode:2008RuGG...49..932K. doi:10.1016/j.rgg.2008.06.012.
^Kontorovich, A. E.; Sokolov, B. S.; Kontorovich, V. A.; Varlamov, A. I.; Grazhdankin, D. V.; Efimov, A. S.; Klets, A. G.; Saraev, S. V.; Terleev, A. A.; Belyaev, S. Yu.; Varaksina, I. V.; Karlova, G. A.; Kochnev, B. B.; Nagavitsin, K. E.; Postnikov, A. A.; Filippov, Yu. F. (2009). "The first section of vendian deposits in the basement complex of the West Siberian petroleum megabasin (resulting from the drilling of the Vostok-3 parametric borehole in the Eastern Tomsk region)". Doklady Earth Sciences. 425 (1): 219–222. Bibcode:2009DokES.425..219K. doi:10.1134/S1028334X09020093. S2CID 129356532.
^Lucas Veríssimo Warren; Fernanda Quaglio; Marcello Guimarães Simões; Claudio Gaucher; Claudio Riccomini; Daniel G. Poiré; Bernardo Tavares Freitas; Paulo C. Boggiani; Alcides Nobrega Sial (2017). "Cloudina-Corumbella-Namacalathus association from the Itapucumi Group, Paraguay: Increasing ecosystem complexity and tiering at the end of the Ediacaran" (PDF). Precambrian Research. 298: 79–87. Bibcode:2017PreR..298...79W. doi:10.1016/j.precamres.2017.05.003. hdl:11449/163140.
Namacalathus is a problematic metazoan fossil occurring in the latest Ediacaran. The first, and only described species, N. hermanastes, was first described...
to the beginning of the Tommotian. The mineralized tubes of Cloudina, Namacalathus, Sinotubulites, and a dozen more of the other organisms from carbonate...
the world, and to the disappearance of distinctive Ediacaran fossils (Namacalathus, Cloudina). Nevertheless, there are arguments that the dated horizon...
from the temporal Terminal Ediacaran biozone. The benthic, calcified Namacalathus is only known from the Nama assemblage, although its affiliations remain...
fossiliferous stratigraphic units in British Columbia Hofmann, Hans J. "Namacalathus-Cloudina assemblage in Neoproterozoic Miette Group (Byng Formation),...
carbonate rich areas of stromatolite reefs. It is found in association with Namacalathus, which like Cloudina was "weakly skeletal" and solitary, and Namapoikia...
the latest Ediacaran of western Siberia, coexisting with Cloudina and Namacalathus. Filaments Filament-shaped structures in Precambrian fossils have been...
the brachiopods and phoronids, and the possible Ediacaran lophophorate Namacalathus. Tentaculitids have ribbed, cone-shaped shells which range in length...
Namibia, in association with other calcifying fossils, Cloudina and Namacalathus. Its mineralogy and accretionary style has been compared with that of...
shelly fossils of prehistoric marine animals, ordered by their type. Namacalathus Yochelsoniella Elements of a scleritome, resembling Halkieria:[clarification...
events: an example is Ausia fenestrata. Analysis performed in 2018 on Namacalathus and Cloudina skeletons from the Ediacaran Omkyk Member of the Nama Group...
spines, made of silica, and are thought to be the remains of sponges. Namacalathus, which may have been a cnidarian, closely related to jellyfish and corals...
occur in higher number – five, six, a dozen – with some resemblance to Namacalathus. The affinity of melanosclerites is uncertain; algal has been proposed...
published by Darroch et al. (2017). Fossils of members of the genus Namacalathus (co-occurring with Cloudina and Corumbella) are reported from the Ediacaran...
the first three-dimensional, pyritized preservation of soft tissue in Namacalathus hermanastes from the Nama Group (Namibia), and evaluate the implications...
africanus. A study of phylogenetic relationships of the Ediacaran animal Namacalathus, interpreting it as a member of Lophotrochozoa related to bryozoans and...
be characteristic of the Cambrian. (The shelly fossils Cloudina and Namacalathus are known from terminal-Ediacaran sediments.) This assemblage has been...
Cloudina aggregates are presented by Mehra & Maloof (2018). A study on Namacalathus and Cloudina skeletons from the Ediacaran Omkyk Member of the Nama Group...