scholarly journals Brachiopod-dominated communities and depositional environment of the Guanshan Konservat-Lagerstätte, eastern Yunnan, China

2020 ◽  
Vol 178 (1) ◽  
pp. jgs2020-043 ◽  
Author(s):  
Feiyang Chen ◽  
Glenn A. Brock ◽  
Zhiliang Zhang ◽  
Brittany Laing ◽  
Xinyi Ren ◽  
...  
Keyword(s):  
Depositional Environment ◽  
Sedimentary Environment ◽  
Low Energy ◽  
Cambrian Explosion ◽  
Early Cambrian ◽  
Tissue Preservation ◽  
Content Type ◽  
Guanshan Biota ◽  
Supplementary Material ◽  
Later Phase

The Guanshan Biota is an unusual early Cambrian Konservat-Lagerstätte from China and is distinguished from all other exceptionally preserved Cambrian biotas by the dominance of brachiopods and a relatively shallow depositional environment. However, the faunal composition, overturn and sedimentology associated with the Guanshan Biota are poorly understood. This study, based on collections through the best-exposed succession of the basal Wulongqing Formation at the Shijiangjun section, Wuding County, eastern Yunnan, China recovered six major animal groups with soft tissue preservation; brachiopods vastly outnumbered all other groups. Brachiopods quickly replace arthropods as the dominant fauna following a transgression at the base of the Wulongqing Formation. A transition from a botsfordiid-, eoobolid- and acrotretid- to an acrotheloid-dominated brachiopod assemblage occurs up-section. Four episodically repeated lithofacies reveal a relatively low-energy, offshore to lower shoreface sedimentary environment at the Shijiangjun section, which is very different from the Wulongqing Formation in the Malong and Kunming areas. Multiple event flows and rapid obrution are responsible for faunal overturn and fluctuation through the section. A detailed lithofacies and palaeontological investigation of this section provides a better understanding of the processes and drivers of faunal overturn during the later phase of the Cambrian Explosion.Supplementary material: Composition and comparison of the Malong Fauna and the Guanshan Biota is are available at: https://doi.org/10.6084/m9.figshare.c.5080799

scholarly journals Tabelliscolex (Cricocosmiidae: Palaeoscolecidomorpha) from the early Cambrian Chengjiang Biota, and the evolution of seriation in Ecdysozoa

2021 ◽  
pp. jgs2021-060
Author(s):  
Xiaomei Shi ◽  
Richard J. Howard ◽  
Gregory D. Edgecombe ◽  
Xianguang Hou ◽  
Xiaoya Ma
Keyword(s):  
Phylogenetic Analyses ◽  
Sensu Stricto ◽  
Cambrian Explosion ◽  
Early Cambrian ◽  
Content Type ◽  
Link Type ◽  
Stem Group ◽  
New Material ◽  
Supplementary Material ◽  
Chengjiang Biota

Cricocosmiidae is a clade of palaeoscolecid-like worms from the Chengjiang Biota, China (Cambrian Stage 3). In contrast to palaeoscolecids sensu stricto, which exhibit tessellating micro-plate trunk ornamentation, cricocosmiids possess larger, serially repeated sets of trunk sclerites bearing resemblance to lobopodian trunk sclerites (e.g., Microdictyon spp.). Cricocosmiidae were therefore proposed as stem-group Panarthropoda in some studies but are recovered as stem-group Priapulida in most phylogenetic analyses. The affinity of cricoscosmiids within Ecdysozoa is therefore of much interest, as is testing the homology of these seriated structures. We report four new specimens of the rare cricocosmiid Tabelliscolex hexagonus, yielding new details of the ventral trunk projections, sclerites and proboscis. New data confirm T. hexagonus possessed paired ventral trunk projections in a consistent seriated pattern, which is also reported from new material of Cricocosmia jinningensis (Cricocosmiidae) and Mafangscolex yunnanensis (Palaeoscolecida sensu stricto). Even when the seriated sclerites and ventral projections of cricocosmiids are coded as homologous with the seriated trunk sclerites and paired appendages, respectively, of lobopodian panarthropods, our tree searches indicate they are convergent. Cricocosmiidae is nested within a monophyletic “Palaeoscolecida sensu lato” clade (Palaeoscolecidomorpha nov.) in stem-group Priapulida. Our study indicates that morphological seriation has independent origins in Scalidophora and Panarthropoda.Thematic collection: This article is part of the Advances in the Cambrian Explosion collection available at: https://www.lyellcollection.org/cc/advances-cambrian-explosionSupplementary material:https://doi.org/10.6084/m9.figshare.c.5551565

Palaeolatitudinal distribution of the Ediacaran macrobiota

2021 ◽  
pp. jgs2021-030
Author(s):  
Catherine E. Boddy ◽  
Emily G. Mitchell ◽  
Andrew Merdith ◽  
Alexander G. Liu
Keyword(s):  
Taxonomic Composition ◽  
Supplementary Information ◽  
Cambrian Explosion ◽  
Content Type ◽  
Link Type ◽  
Environmental Perturbations ◽  
Significant Difference ◽  
Evolutionary Trajectories ◽  
Cambrian Radiation ◽  
Supplementary Material

Macrofossils of the late Ediacaran Period (c. 579–539 Ma) document diverse, complex multicellular eukaryotes, including early animals, prior to the Cambrian radiation of metazoan phyla. To investigate the relationships between environmental perturbations, biotic responses and early metazoan evolutionary trajectories, it is vital to distinguish between evolutionary and ecological controls on the global distribution of Ediacaran macrofossils. The contributions of temporal, palaeoenvironmental and lithological factors in shaping the observed variations in assemblage taxonomic composition between Ediacaran macrofossil sites are widely discussed, but the role of palaeogeography remains ambiguous. Here we investigate the influence of palaeolatitude on the spatial distribution of Ediacaran macrobiota through the late Ediacaran Period using two leading palaeogeographical reconstructions. We find that overall generic diversity was distributed across all palaeolatitudes. Among specific groups, the distributions of candidate ‘Bilateral’ and Frondomorph taxa exhibit weakly statistically significant and statistically significant differences between low and high palaeolatitudes within our favoured palaeogeographical reconstruction, respectively, whereas Algal, Tubular, Soft-bodied and Biomineralizing taxa show no significant difference. The recognition of statistically significant palaeolatitudinal differences in the distribution of certain morphogroups highlights the importance of considering palaeolatitudinal influences when interrogating trends in Ediacaran taxon distributions.Supplementary material: Supplementary information, data and code are available at https://doi.org/10.6084/m9.figshare.c.5488945Thematic collection: This article is part of the Advances in the Cambrian Explosion collection available at: https://www.lyellcollection.org/cc/advances-cambrian-explosion

scholarly journals Discussion on ‘Tabelliscolex (Cricocosmiidae: Palaeoscolecidomorpha) from the early Cambrian Chengjiang Biota and the evolution of seriation in Ecdysozoa’ by Shi et al. 2021 (JGS, jgs2021-060)

2021 ◽  
pp. jgs2021-111
Author(s):  
Martin R. Smith ◽  
Alavya Dhungana
Keyword(s):  
Bayesian Approach ◽  
Early Cambrian ◽  
Content Type ◽  
Animal Body ◽  
Link Type ◽  
Stem Group ◽  
Cambrian Radiation ◽  
Supplementary Material ◽  
Chengjiang Biota

Exceptionally preserved fossils are key to reconstructing the origin of the modern animal body plans in the Cambrian radiation. The Panarthropod phyla Euarthropoda, Onychophora and Tardigrada have roots in a ‘lobopodian’ grade typified by broadly cylindrical organisms with sclerotized dorsal plates and paired ventral projections. A similar anatomical configuration has been taken to link certain palaeoscolecid worms with the earliest ecdysozoans. Shi et al. (2021) contend that these similarities evolved convergently, and that palaeoscolecids are priapulan relatives with little bearing on the panarthropod evolution.Here we show that this conclusion holds only under a particular treatment of inapplicable character states with known shortcomings. When inapplicable tokens are handled more rigorously, palaeoscolecids are most parsimoniously reconstructed as stem-group panarthropods with homologous dorsal plates and ventral projections – highlighting the degree to which the treatment of inapplicable data can influence fundamental evolutionary conclusions. As the position of palaeoscolecids depends so strongly on the underlying methodology, and is highly uncertain under a Bayesian approach, we consider it premature to exclude the possibility that panarthropods evolved from a grade of palaeoscolecids with dorsal plates and ventral projections.Supplementary material:https://doi.org/10.6084/m9.figshare.16419522

Terreneuvian bio- and chemostratigraphy of the South Sichuan Region (South China)

2021 ◽  
pp. jgs2020-167
Author(s):  
Ben Yang ◽  
Michael Steiner
Keyword(s):  
Carbon Isotope ◽  
South China ◽  
Cambrian Explosion ◽  
The South ◽  
Yangtze Craton ◽  
Content Type ◽  
Link Type ◽  
Small Shelly Fossils ◽  
Assemblage Zone ◽  
Supplementary Material

Classical sections, such as the Maidiping and Daqiao Mine sections of South Sichuan (China), expose early Cambrian deposits that are crucial for understanding the biological and environmental evolution of Yangtze Craton. These sequences are rich in Terreneuvian small shelly fossils, which can be assigned to assemblages I and III from South China. The Anabarites trisulcatus– Protohertzina anabarica Assemblage Zone (Assemblage I) is recognized at the lower Maidiping Formation. The second assemblage (Paragloborilus subglobosus – Purella squamulosa Assemblage Zone) cannot be verified in South Sichuan, although previous reports claimed its existence based on the occurrence of Paragloborilus subglobosus. The third assemblage (Watsonella crosbyi Assemblage Zone) is confirmed in the upper Maidiping Formation. The abundant bioclasts in this interval indicate abrasions and bioerosions by winnowing or starved sedimentation. Carbon isotope values from the Maidiping section present no negative excursion at the presumed Ediacaran–Cambrian transition. A positive carbon isotope excursion is observed in the upper Maidiping Formation (Assemblage III) which is correlated to the ZHUCE excursion in the Dahai Member of eastern Yunnan. The shallow water deposits of South Sichuan can be correlated with the South China, western Mongolia and Siberia successions based on biozonations and carbon isotope trends.Thematic collection: This article is part of the Advances in the Cambrian Explosion collection available at: https://www.lyellcollection.org/cc/advances-cambrian-explosionSupplementary material:https://doi.org/10.6084/m9.figshare.c.5326834

New vauxiid sponges from the Chengjiang Biota and their evolutionary significance

2021 ◽  
pp. jgs2020-162
Author(s):  
Fan Wei ◽  
Yang Zhao ◽  
Ailin Chen ◽  
Xianguang Hou ◽  
Peiyun Cong
Keyword(s):  
South China ◽  
Vertical Surface ◽  
Cambrian Explosion ◽  
Evolutionary Significance ◽  
Early Cambrian ◽  
Geological History ◽  
Burgess Shale ◽  
Content Type ◽  
Dermal Layer ◽  
Chengjiang Biota

Aspiculate demosponges are rarely described in geological history on account of the absence of spicules that are stable and resistant to degradation. One exception is the exquisite preservation of sponges without any mineralised skeletons discovered in Lagerstätten (e.g. the Burgess Shale). The Chengjiang Biota, an early example of a Burgess Shale-type Biota in South China (Cambrian Series 2, Stage 3), is one of the only examples of convincing aspiculate sponges until now. Here, we describe Vauxia pregracilenta sp. nov. and V. paraleioia sp. nov., as well as two poorly preserved vauxiid specimens (Vauxia sp.) in open nomenclature, from the Chengjiang Biota. V. pregracilenta has a fan-like holdfast and branches in various sizes, as well as a typical two-layered net-like skeleton, without spicules. The endosomal layer is hexagonal, while the dermal layer is sub-rectangular. V. paraleioia is characterised by a two-layered subconical skeleton, with the dermal layer ornamented with vertical surface grooves. The openings of the dermal and endosomal layers of V. paraleioia are both hexagonal but of different sizes. These newly discovered Vauxia species indicate that the aspiculate sponges were diversified in the early Cambrian period. Partial silicification of the fibres of aspiculate Vauxia are confirmed from the Chengjiang Biota.Thematic collection: This article is part of the Advances in the Cambrian Explosion collection available at: https://www.lyellcollection.org/cc/advances-cambrian-explosion

Spatial heterogeneity of redox-sensitive trace metal enrichments in upper Ediacaran anoxic black shales

2021 ◽  
pp. jgs2020-234
Author(s):  
Chengsheng Jin ◽  
Chao Li ◽  
Thomas J. Algeo ◽  
Guochang Wang ◽  
Wei Shi ◽  
...  
Keyword(s):  
Spatial Heterogeneity ◽  
Water Mass ◽  
Significant Degree ◽  
Black Shales ◽  
Redox Conditions ◽  
Cambrian Explosion ◽  
Content Type ◽  
Oxygen Levels ◽  
Link Type ◽  
Supplementary Material

The Ediacaran radiation of metazoans is widely thought to have been triggered by an increase in atmospheric and oceanic oxygen levels. Although supported by other proxies, rising oxygen levels were deduced to a significant degree from sedimentary enrichments of redox-sensitive trace elements (RSTEs). However, some organic-rich shales of this period show only minor enrichments in RSTEs, leaving the significance of RSTE data for palaeo-oxygenation interpretations in doubt. We measured and compiled proxies for marine redox conditions (Fe species, RSTEs), total organic carbon (TOC) and water mass restriction (Mo/TOC and Co × Mn v. Cd/Mo) in the intra-shelf Jiulongwan and basinal Sandu sections of the Nanhua Basin in South China. Compared with the same proxies from coeval sections in the Nanhua Basin and globally, our results document a strong spatial heterogeneity of RSTE enrichments in anoxic black shales during the late Ediacaran. We infer that RSTE enrichments were strongly influenced by local factors, such as basinal restriction, seawater RSTE concentrations, and differential elemental responses to redox conditions and other influences. The broader significance of our findings is that they highlight the difficulty of investigating global redox conditions based on an analysis of local RSTE proxies within a single depositional basin or a limited number of study sections.Thematic collection: This article is part of the Advances in the Cambrian Explosion collection available at: https://www.lyellcollection.org/cc/advances-cambrian-explosionSupplementary material: Tables S1–S3 are available at https://doi.org/10.6084/m9.figshare.c.5325047

Fuxianhuiids are mandibulates and share affinities with total-group Myriapoda

2021 ◽  
pp. jgs2020-246 ◽  
Author(s):  
Cédric Aria ◽  
Fangchen Zhao ◽  
Maoyan Zhu
Keyword(s):  
Phylogenetic Analysis ◽  
Sister Group ◽  
Cambrian Explosion ◽  
Content Type ◽  
Total Group ◽  
Link Type ◽  
Supplementary Material ◽  
Ecological Success ◽  
Chengjiang Biota ◽  
Additional Support

In spite of their unrivalled ecological success, the origins of terrestrial mandibulates have long remained virtually unknown. In recent years, claims have been made based on phylogenetic results that fuxianhuiids, iconic fossils of the Chengjiang biota and purported basal euarthropods, were in fact mandibulates, allied with the problematic euthycarcinoids as the closest sister-group to Mandibulata or even stem myriapods. A re-examination of euthycarcinoid mouthparts has since brought additional support to this view. Here, we reinvestigated the anterior anatomy of the Cambrian euarthropod Fuxianhuia and its relatives. We demonstrate that the fuxianhuiid head is that of a mandibulate, sharing similarities with hymenocarines, including a limbless intercalary segment. The hypostome is a sub-triangular sclerite partially fused but anatomically independent from a large, bilobed labral plate, as observed in many extant mandibulate taxa as well as euthycarcinoids. The so-called ‘specialized post-antenn(ular) appendages' are therefore the mandibles, with a tripartite palp and large dented gnathal lobe partially covered by the hypostome-labrum complex. Under a ‘deep split' phylogenetic scenario, Fuxianhuia and its relatives are here resolved as sister-group to crown Mandibulata.Thematic collection: This article is part of the Advances in the Cambrian Explosion collection available at: https://www.lyellcollection.org/cc/advances-cambrian-explosionSupplementary material: Additional remarks on terminology, morphological interpretations and a list of modified/new characters used for the phylogenetic analysis are available at https://doi.org/10.6084/m9.figshare.c.5305042

scholarly journals Geochemistry of the black rock series of lower Cambrian Qiongzhusi Formation, SW Yangtze Block, China: Reconstruction of sedimentary and tectonic environments

2021 ◽  
Vol 13 (1) ◽  
pp. 166-187
Author(s):  
Hao Liu ◽  
Chan Wang ◽  
Yong Li ◽  
Jianghong Deng ◽  
Bin Deng ◽  
...  
Keyword(s):  
Environmental Changes ◽  
Sedimentary Environment ◽  
Hydrothermal Fluids ◽  
Early Cambrian ◽  
Rock Series ◽  
Yangtze Block ◽  
Tectonic Environment ◽  
Weathering Intensity ◽  
Black Rock Series ◽  
Tectonic System

Abstract The black rock series in the Qiongzhusi Formation contains important geochemical information about the early Cambrian tectonic and ecological environment of the southwestern Yangtze Block. In this paper, major, trace, and rare earth element data are presented in an attempt to reveal the sediment source during the deposition of the early Cambrian Qiongzhusi Formation and to reconstruct the sedimentary tectonic environment and weathering intensity during that time. The basin primarily received continental clastic material with neutral-acidic igneous rocks from a stable source and with a moderate level of maturity during the depositional period of the Qiongzhusi Formation. Furthermore, the strata were weakly influenced by submarine hydrothermal fluids during diagenesis. The reconstruction of the sedimentary environment and weathering intensity shows that P2O5 enrichment and water body stratification occurred due to the effects of upwelling ocean currents during the depositional period of the Qiongzhusi Formation. The combination of upwelling and bottom-water hydrothermal fluids led to environmental changes in the study area, from dry and hot to moist and warm. Last, the reconstruction of the tectonic environment of the Qiongzhusi Formation indicates that deposition occurred in continental slope and marginal marine environments associated with a continental arc tectonic system. These findings provide an essential basis for the comprehensive reconstruction of the early Cambrian sedimentary environment of the Yangtze Block.

scholarly journals Current understanding on the Cambrian Explosion: questions and answers

PalZ ◽  
2021 ◽  
Author(s):  
Xingliang Zhang ◽  
Degan Shu
Keyword(s):  
Environmental Changes ◽  
Size Variation ◽  
Progressive Increase ◽  
Cambrian Explosion ◽  
Time Interval ◽  
Early Cambrian ◽  
Ecological Processes ◽  
Questions And Answers ◽  
Evolutionary Event ◽  
History Of

AbstractThe Cambrian Explosion by nature is a three-phased explosion of animal body plans alongside episodic biomineralization, pulsed change of generic diversity, body size variation, and progressive increase of ecosystem complexity. The Cambrian was a time of crown groups nested by numbers of stem groups with a high-rank taxonomy of Linnaean system (classes and above). Some stem groups temporarily succeeded while others were ephemeral and underrepresented by few taxa. The high number of stem groups in the early history of animals is a major reason for morphological gaps across phyla that we see today. Most phylum-level clades achieved their maximal disparity (or morphological breadth) during the time interval close to their first appearance in the fossil record during the early Cambrian, whereas others, principally arthropods and chordates, exhibit a progressive exploration of morphospace in subsequent Phanerozoic. The overall envelope of metazoan morphospace occupation was already broad in the early Cambrian though it did not reach maximal disparity nor has diminished significantly as a consequence of extinction since the Cambrian. Intrinsic and extrinsic causes were extensively discussed but they are merely prerequisites for the Cambrian Explosion. Without the molecular evolution, there could be no Cambrian Explosion. However, the developmental system is alone insufficient to explain Cambrian Explosion. Time-equivalent environmental changes were often considered as extrinsic causes, but the time coincidence is also insufficient to establish causality. Like any other evolutionary event, it is the ecology that make the Cambrian Explosion possible though ecological processes failed to cause a burst of new body plans in the subsequent evolutionary radiations. The Cambrian Explosion is a polythetic event in natural history and manifested in many aspects. No simple, single cause can explain the entire phenomenon.

Role of BIM and energy simulation tools in designing zero-net energy homes

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Shahryar Habibi
Keyword(s):  
Energy Efficiency ◽  
Built Environment ◽  
Design Process ◽  
Simulation Software ◽  
Energy Simulation ◽  
Low Energy ◽  
Net Energy ◽  
Content Type ◽  
Zero Net Energy

Purpose The purpose of this study is to design a zero-energy home, which is known to be capable of balancing its own energy production and consumption close to zero. Development of low-energy homes and zero-net energy houses (ZEHs) is vital to move toward energy efficiency and sustainability in the built environment. To achieve zero or low energy targets in homes, it is essential to use the design process that minimizes the need for active mechanical systems. Design/methodology/approach The methodology discussed in this paper consists of an interfacing building information modeling (BIM) tool and a simulation software to determine the potential influence of phase change materials on designing zero-net energy homes. Findings BIM plays a key role in advancing methods for architects and designers to communicate through a common software platform, analyze energy performance through all stages of the design and construction process and make decisions for improving energy efficiency in the built environment. Originality/value This paper reviews the literature relevant to the role of BIM in helping energy simulation for the performance of residential homes to more advanced levels and in modeling the integrated design process of ZEHs.

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