Abstract This work presents a detailed taxonomic study on organic-walled microfossils from the Ediacaran Sete Lagoas Formation (Bambuí Group) at the Barreiro section in the Januária area of the São Francisco basin, Brazil. Seven species are described, includingSiphonophycus robustum(Schopf, 1968),Ghoshia januarensisnew species,Leiosphaeridia crassa(Naumova, 1949),Leiosphaeridia jacutica(Timofeev, 1966),Leiosphaeridia minutissima(Naumova, 1949),Leiosphaeridia tenuissimaEisenack, 1958, and Germinosphaera bispinosaMikhailova, 1986. These taxa are recovered for the first time in the Sete Lagoas Formation. They occur abundantly in the lower portion of the studied section, but onlyGhoshia januarensisis present in the upper part of the studied section, probably due to environmental or taphonomic changes.Leiosphaeridiaspecies, particularlyLeiosphaeridia minutissima, dominate the organic-walled microfossil assemblage. Although most taxa described here have long stratigraphic ranges, they are consistent with a terminal Ediacaran age as inferred from detrital zircon data and tubular fossils (e.g.,CloudinaandCorumbella) from the Sete Lagoas Formation. UUID:http://zoobank.org/7f92b900-0176-4da6-93a3-fd51edb22cbf
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The rangeomorph fossil Charnia from the Ediacaran Shibantan biota in the Yangtze Gorges area, South China
Abstract The terminal Ediacaran Shibantan biota (~550–543 Ma) from the Dengying Formation in the Yangtze Gorges area of South China represents one of the rare examples of carbonate-hosted Ediacara-type macrofossil assemblages. In addition to the numerically dominant taxa—the non-biomineralizing tubular fossilWutubusand discoidal fossilsAspidellaandHiemalora, the Shibantan biota also bears a moderate diversity of frondose fossils, includingPteridinium,Rangea,Arborea, andCharnia. In this paper, we report two species of the rangeomorph genusCharnia, including the type speciesCharnia masoniFord, 1958 emend. andCharnia gracilisnew species, from the Shibantan biota. Most of the ShibantanCharniaspecimens preserve only the petalodium, with a few bearing the holdfast and stem. Despite overall architectural similarities to otherCharniaspecies, the Shibantan specimens ofCharnia gracilisn. sp. are distinct in their relatively straight, slender, and more acutely angled first-order branches. They also show evidence that may support a two-stage growth model and a epibenthic sessile lifestyle.Charniafossils described herein represent one of the youngest occurrences of this genus and extend its paleogeographic and stratigraphic distributions. Our discovery also highlights the notable diversity of the Shibantan biota, which contains examples of a wide range of Ediacaran morphogroups. UUID:http://zoobank.org/837216cd-4a4a-4e13-89e2-ee354ba48a4c
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- Award ID(s):
- 2021207
- PAR ID:
- 10540442
- Publisher / Repository:
- Cambridge University Press
- Date Published:
- Journal Name:
- Journal of Paleontology
- ISSN:
- 0022-3360
- Page Range / eLocation ID:
- 1 to 17
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract Bituminous limestone of the Ediacaran Shibantan Member of the Dengying Formation (551–539 Ma) in the Yangtze Gorges area contains a rare carbonate-hosted Ediacara-type macrofossil assemblage. This assemblage is dominated by the tubular fossil Wutubus Chen et al., 2014 and discoidal fossils, e.g., Hiemalora Fedonkin, 1982 and Aspidella Billings, 1872, but frondose organisms such as Charnia Ford, 1958, Rangea Gürich, 1929, and Arborea Glaessner and Wade, 1966 are also present. Herein, we report four species of Arborea from the Shibantan assemblage, including the type species Arborea arborea (Glaessner in Glaessner and Daily, 1959) Glaessner and Wade, 1966, Arborea denticulata new species, and two unnamed species, Arborea sp. A and Arborea sp. B. Arborea arborea is the most abundant frond in the Shibantan assemblage. Arborea denticulata n. sp. resembles Arborea arborea in general morphology but differs in its fewer primary branches and lower length/width ratio of primary branches. Arborea sp. A and Arborea sp. B are fronds with a Hiemalora -type basal attachment. Sealing by microbial mats and authigenic cementation may have played an important role in the preservation of Arborea in the Shibantan assemblage. The Shibantan material of Arborea extends the stratigraphic, ecological, and taphonomic ranges of this genus. UUID: http://zoobank.org/554f21da-5f09-4891-9deb-cbc00c41e5f1more » « less
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