New Siliceous Microfossils from the Terreneuvian Yanjiahe Formation, South China: The Possible Earliest Radiolarian Fossil Record

Chang, Shan Chwen; Feng, Qinglai; Zhang, Lei

doi:10.1007/s12583-017-0960-0

Cited by 21 publications

(6 citation statements)

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“…Any biogenic silica sink that existed in the earliest Cambrian was evidently inadequate to effectively draw down seawater silica concentration. This is consistent with the reportedly sparse occurrence and low abundance of silica-secreting organisms at that time (Antcliffe et al, 2014;Braun et al, 2007;Chang et al, 2018). In contrast, however, silicarich seawater would have favoured silica biomineralization and fossil preservation (e.g.…”

Section: Discussionsupporting

confidence: 86%

“…Conley et al, 2017). During the Ediacaran-Cambrian (E-C) transition, silica-secreting organisms such as sponges (Antcliffe et al, 2014;Mazumdar & Banerjee, 1998) and possible radiolarians (Braun et al, 2007;Chang et al, 2018), gradually appeared and diversified. At the same time, bedded cherts were extensively deposited in shallow subtidal to basinal environments on multiple continents (Brasier et al, 2011;Table DR1).…”

Section: Introductionmentioning

confidence: 99%

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Silica‐rich seawater in the early Cambrian: Sedimentological evidence from bedded cherts

et al. 2021

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The effects and timing of the evolution of siliceous sponge and radiolarians on the mode of silica burial and oceanic silica cycling in the early Cambrian are still controversial. Bedded cherts of the lower Cambrian Yurtus Formation deposited in a subtidal shelf environment. They display diagnostic sedimentary features, including intraclastic chert grains, edgewise chert breccias, weakly compacted grains and ripup clasts, and rapid silica cementation, collectively indicating primary and very early silicification at and near the sediment-water interface. This depositional mode contrasts with Phanerozoic biogenic cherts but is comparable with that of Precambrian cherts precipitated from silica-rich seawater. The Yurtus cherts therefore provide direct and compelling sedimentological evidence of the continuation of silica-rich seawater into the early Cambrian, consistent with the extensive coeval chert depositions elsewhere. These results contrast with the long-held view of rapid decline in seawater silica concentrations in the earliest Phanerozoic, and elucidate coeval Si-coupled geochemical cycling, silica-biomineralization and fossil preservation.

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Section: Discussionsupporting

confidence: 86%

Section: Introductionmentioning

confidence: 99%

Silica‐rich seawater in the early Cambrian: Sedimentological evidence from bedded cherts

et al. 2021

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“…The Ediacaran Dengying Formation carbonates are disconformably overlain by Terreneuvian (Fortunian-Stage 2) lower Cambrian deposits. The lowermost Cambrian unit is the Yanjiahe Formation, containing abundant small shelly fossils (SSF) that are assigned to three SSF assemblage zones (in ascending order): the Anabarites trisulcatus-Protohertzina anabarica assemblage zone, the Purella antiqua assemblage zone, and the Aldanella yanjiaheensis assemblage zone (Guo et al, 2008(Guo et al, , 2014Chang et al, 2017Chang et al, , 2018Steiner et al, 2020). The Shuijingtuo Formation (black shale and limestone) disconformably overlies the Yanjiahe Formation, and has yielded abundant and diverse shelly fossils, including brachiopods, in addition to the oldest eodiscoid trilobites in South China (Wang et al, 1987;Lin et al, 2004;Steiner et al, 2007;Dai and Zhang, 2011;Yang et al, 2015;Z.L.…”

Section: Geological Settingmentioning

confidence: 99%

Early Cambrian (Stage 4) brachiopods from the Shipai Formation in the Three Gorges area of South China

et al. 2021

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Diverse and abundant fossil taxa have been described in the lower Cambrian Shipai Formation in the Three Gorges area of Hubei Province, South China, but the taxonomy and diversity of the co-occurring brachiopod fauna are still far from clear. Here we describe the brachiopod fauna recovered from the Shipai Formation in the Three Gorges area of South China, including representatives of the subphylum Linguliformea: linguloids (Lingulellotreta ergalievi, Eoobolus malongensis, and Neobolidae gen. indet. sp. indet.), and an acrotretoid (Linnarssonia sapushanensis); and representatives from the subphylum Rhynchonelliformea: the calcareous-shelled Kutorginates (Kutorgina sinensis, Kutorgina sp., and Nisusia liantuoensis). This brachiopod assemblage and the first occurrence of Linnarssonia sapushanensis shell beds permit correlation of the Shipai Formation in the Three Gorges area of Hubei Province with the Stage 4 Wulongqing Formation in the Wuding area of eastern Yunnan. This correlation is further strengthened by the first appearance datum (FAD) of the rhynchonelliform brachiopod Nisusia in the upper silty mudstone of both the Shipai and Wulongqing formations. The new well-preserved material, derived from siliciclastic rocks, also gives critical new insights into the fine shell structure of L. sapushanensis. Microstructural studies on micromorphic acrotretoids (like Linnarssonia) have previously been restricted to fossils that were acid-etched from limestones. This is the first study to carry out detailed comparative ultrastructural studies on acrotretoid shells preserved in siliciclastic rocks. This work reveals a hollow tube and solid column microstructure in the acrotretoid shells from the Shipai Formation, which is likely to be equivalent of traditional column and central canal observed in shells dissolved from limestones.

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“…The silty shale contains macrofossils such as algae and enigmatic metazoans (Yanjiahella and Protoconites minor studied herein) (Guo et al, 2008(Guo et al, , 2009(Guo et al, , 2010a(Guo et al, , 2012Topper et al, 2019). Abundant shelly fossils (Purella antiqua Zone) (Guo et al, 2014) and the possible earliest radiolarian (Chang et al, 2018b) occur in siliceousphosphatic nodules in Bed 3. Bed 4 is 4.7 m thick and consists of non-fossiliferous carbonaceous limestone.…”

Section: Locality and Stratigraphymentioning

confidence: 99%

Geometric morphometric analysis of Protoconites minor from the Cambrian (Terreneuvian) Yanjiahe Formation in Three Gorges, South China

Guo

Chen²,

Song

et al. 2020

Palaeontol Electron

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The Ediacaran to Cambrian transition is a critical interval of time during which major evolutionary changes occurred. Recently, abundant Protoconites minor have been recovered from the silty shales of the lower Cambrian Yanjiahe Formation (Terreneuvian, Fortunian-Stage 2) in the Three Gorges area of South China. These fossils represent an important ecological diversification of macroscopic organisms at the onset of the Cambrian. Protoconites minor is a probable cnidarian-grade organism preserved by carbon compression. Herein, geometric morphometric analyses are applied to crack out specimens of P. minor to reveal any cryptic morphological details that may have implications for their morphological diversity, ontogenetic processes, and taxonomic identification. These statistical analyses reveal a strong relationship between size and shape, which indicates that the overall shape of P. minor was mainly controlled by allometric growth. The smaller specimens are generally wider at the anterior and more commonly have straight-sides. Larger individuals tend to be narrower at the anterior, with bending more common. Our analyses demonstrate that there are transitional forms between larger, strongly bent specimens and smaller, straight specimens, suggesting that the assemblage likely consists of a single species.

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New Siliceous Microfossils from the Terreneuvian Yanjiahe Formation, South China: The Possible Earliest Radiolarian Fossil Record

Cited by 21 publications

References 31 publications

Silica‐rich seawater in the early Cambrian: Sedimentological evidence from bedded cherts

Silica‐rich seawater in the early Cambrian: Sedimentological evidence from bedded cherts

Early Cambrian (Stage 4) brachiopods from the Shipai Formation in the Three Gorges area of South China

Geometric morphometric analysis of Protoconites minor from the Cambrian (Terreneuvian) Yanjiahe Formation in Three Gorges, South China

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