scholarly journals A xandarellid artiopodan from Morocco – a middle Cambrian link between soft-bodied euarthropod communities in North Africa and South China

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Javier Ortega-Hernández ◽  
Abdelfattah Azizi ◽  
Thomas W. Hearing ◽  
Thomas H. P. Harvey ◽  
Gregory D. Edgecombe ◽  
...  
Keyword(s):  
New Species ◽  
North Africa ◽  
South China ◽  
Early Cambrian ◽  
Burgess Shale ◽  
Middle Cambrian ◽  
West Gondwana ◽  
Lower Palaeozoic ◽  
Chengjiang Biota ◽  
Stratigraphic Range

Abstract Xandarellida is a well-defined clade of Lower Palaeozoic non-biomineralized artiopodans that is exclusively known from the early Cambrian (Stage 3) Chengjiang biota of South China. Here we describe a new member of this group, Xandarella mauretanica sp. nov., from the middle Cambrian (Stage 5) Tatelt Formation of Morocco, making this the first non-trilobite Cambrian euarthropod known from North Africa. X. mauretanica sp. nov. represents the youngest occurrence of Xandarellida – extending its stratigraphic range by approximately 10 million years – and expands the palaeobiogeographic distribution of the group to the high southern palaeolatitudes of West Gondwana. The new species provides insights into the lightly sclerotized ventral anatomy of Xandarellida, and offers stratigraphically older evidence for a palaeobiogeographic connection between Burgess Shale-type euarthropod communities in North Africa and South China, relative to the (Tremadocian) Fezouata biota.

Occurrence of the eudemersal radiodont Cambroraster in the early Cambrian Chengjiang Lagerstätte and the diversity of hurdiid ecomorphotypes

2020 ◽  
Vol 157 (7) ◽  
pp. 1200-1206 ◽  
Author(s):  
Yu Liu ◽  
Rudy Lerosey-Aubril ◽  
Denis Audo ◽  
Dayou Zhai ◽  
Huijuan Mai ◽  
...  
Keyword(s):  
New Species ◽  
South China ◽  
Early Cambrian ◽  
Burgess Shale ◽  
Stem Group ◽  
Lower Palaeozoic ◽  
Trophic Webs ◽  
Chengjiang Lagerstätte ◽  
A New Species

AbstractRadiodonts are a diverse clade of Lower Palaeozoic stem-group euarthropods that played a key role in the emergence of complex marine trophic webs. The latest addition to the group, Cambroraster falcatus, was recently described from the Wuliuan Burgess Shale, and is characterized by a unique horseshoe-shaped central carapace element. Here we report the discovery of Cambroraster sp. nov. A, a new species from the Cambrian Stage 3 Chengjiang Lagerstätte of South China. The new occurrence of Cambroraster demonstrates that some of the earliest known radiodonts had already evolved a highly derived carapace morphology adapted to an essentially eudemersal life as sediment foragers.

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

New well-preserved scleritomes of Chancelloriida from early Cambrian Guanshan Biota, eastern Yunnan, China

2018 ◽  
Vol 92 (6) ◽  
pp. 955-971 ◽  
Author(s):  
Jun Zhao ◽  
Guo-Biao Li ◽  
Paul A. Selden
Keyword(s):  
New Species ◽  
Detailed Comparison ◽  
The Body ◽  
Single Element ◽  
Early Cambrian ◽  
Top Down ◽  
Middle Cambrian ◽  
Unusual Form ◽  
Guanshan Biota ◽  
A New Species

AbstractA large number of well-preserved chancelloriid scleritomes from the Guanshan biota, early Cambrian of Yunnan, China, are described as a new species,Allonnia tenuisn. sp., and provide solid evidence for the original appearance of these enigmatic animals, based on specimens compacted laterally and top-down. With the assistance of a flexible integument, chancelloriids, especiallyAllonniafrom early and middle Cambrian, may have had the ability to partially or completely expand and contract the body, which might have played an important role in feeding. A new metazoan with single-element spines,Nidelric gaoloufangensisn. sp., is also described. Preservation and affinity are discussed. Detailed comparison of the morphology of the body and spines of this metazoan indicate that it shares many similarities with chancelloriids, of which it may be an unusual form.UUID:http://zoobank.org/2708d95a-1fae-46fc-afea-9707ae97a4d7

Lower Cambrian (Branchian) trilobites and biostratigraphy of the Hanford Brook Formation, southern New Brunswick

2000 ◽  
Vol 74 (5) ◽  
pp. 858-878 ◽  
Author(s):  
Stephen R. Westrop ◽  
Ed Landing
Keyword(s):  
New Species ◽  
Nova Scotia ◽  
North America ◽  
New Brunswick ◽  
Lower Cambrian ◽  
Early Cambrian ◽  
The West ◽  
Middle Cambrian ◽  
Sequence Stratigraphic ◽  
Two New Species

The Hanford Brook Formation, one of the classic Cambrian units of Avalonian North America, contains at least eight species of endemic trilobites, including Berabichia milleri Westrop n. sp., that are assigned to seven genera. The vertical succession of faunas is far more complex than has been recognized previously, with each member containing a lithofacies-specific assemblage. These are, in ascending order: a bradoriid-linguloid Association without trilobites in the nearshore St. Martin's Member, a Protolenus Association in dysaerobic siltstones and sandstones of the Somerset Street Member, and a Kingaspidoides-Berabichia Association in hummocky cross-stratified sandstones of the Long Island Member that overlie a parasequence boundary at Hanford Brook. Due to the breakdown of biogeographic barriers in the late Early Cambrian, two new species-based zones, the Protolenus elegans and Kingaspidoides cf. obliquoculatus zones, share trilobite genera with the Tissafinian Stage of Morocco. This generic similarity has been the basis for correlation of this upper Lower Cambrian interval on the Avalon continent with the West Gondwanan lowest Middle Cambrian. However, the clear facies control on the occurrence of genera in the Hanford Brook Formation and the presence of an abrupt faunal break and unconformity at the base of the Tissafinian in Morocco makes this correlation questionable. The Hanford Brook Formation may represent a late Early Cambrian interval unknown in Gondwana. Sequence-stratigraphic criteria even raise the possibility that the Protolenus Association is the biofacies equivalent of Callavia broeggeri Zone faunas of the Brigus Formation of Newfoundland, Nova Scotia and Massachusetts.

Rare primitive deuterostomes from the Cambrian (Series 3) of Utah

2015 ◽  
Vol 89 (4) ◽  
pp. 631-636 ◽  
Author(s):  
Simon Conway Morris ◽  
Susan L. Halgedahl ◽  
Paul Selden ◽  
Richard D. Jarrard
Keyword(s):  
New Species ◽  
Fossil Record ◽  
Type Species ◽  
The Body ◽  
New Taxon ◽  
Burgess Shale ◽  
Anterior Section ◽  
Stem Group ◽  
Stratigraphic Range ◽  
New Discovery

AbstractThe fossil record of early deuterostome history largely depends on soft-bodied material that is generally rare and often of controversial status. Banffiids and vetulicystids exemplify these problems. From the Cambrian (Series 3) of Utah, we describe specimens of Banffia episoma n. sp. (from the Spence Shale) and Thylacocercus ignota n. gen. n. sp. (from the Wheeler Formation). The new species of Banffia Walcott, 1911 shows significant differences to the type species (B. constricta Walcott, 1911) from the Cambrian (Series 3, Stage 5) Burgess Shale, notably in possessing a prominent posterior unit but diminished anterior section. Not only does this point to a greater diversity of form among the banffiids, but also B. episoma indicates that the diagnostic median constriction and crossover of either side of the body are unlikely to be the result of taphonomic twisting but are original features. Comparisons extend also to the Cambrian (Series 2) Heteromorphus Luo and Hu in Luo et al., 1999 and, collectively, these observations support an assignment of the banffiids to the vetulicolians. The new taxon T. ignota represents the first discovery of a vetulicystid from beyond China and also significantly extends its stratigraphic range from Series 2 Cambrian into Series 3 Cambrian. Despite overall similarities in bodyplan, T. ignota differs from other vetulicystids in a number of respects, notably the possession of an anterior zone with broad tentacle-like structures. This new discovery is consistent with the vetulicystids representing stem-group ambulacrarians.

Herpetogaster from the early Cambrian of Nevada (Series 2, Stage 4) and its implications for the evolution of deuterostomes

2018 ◽  
Vol 156 (1) ◽  
pp. 172-178 ◽  
Author(s):  
JULIEN KIMMIG ◽  
RONALD C. MEYER ◽  
BRUCE S. LIEBERMAN
Keyword(s):  
Early Cambrian ◽  
Burgess Shale ◽  
Middle Cambrian ◽  
Stage 4 ◽  
First Occurrence

AbstractThe Pioche Formation of SE Nevada preserves a diverse soft-bodied fauna from the early and middle Cambrian (Series 2–3: Stage 4–5). While the fauna is dominated by arthropods, animals belonging to other taxa can be found. Here we document the first occurrence of Herpetogaster collinsi outside the Burgess Shale. Further, the specimens are from the Nephrolenellus multinodus biozone and thus represent the oldest occurrence of the species, as well as possibly the earliest soft-bodied deuterostomes in Laurentia.

Asynchronous trilobite extinctions at the early to middle Cambrian transition

Geology ◽  
2020 ◽  
Vol 48 (5) ◽  
pp. 441-445 ◽  
Author(s):  
F.A. Sundberg ◽  
K.E. Karlstrom ◽  
G. Geyer ◽  
J.R. Foster ◽  
J.W. Hagadorn ◽  
...  
Keyword(s):  
Critical Time ◽  
Data Sets ◽  
Early Cambrian ◽  
Earth System ◽  
Middle Cambrian ◽  
West Gondwana ◽  
Paleoclimatic Data ◽  
First Time ◽  
Age Constraints ◽  
Prior Models

Abstract Trilobites appeared and diversified rapidly in the Cambrian, but it is debated as to whether their radiations and extinctions were globally synchronous or geographically restricted and diachronous. The end of the early Cambrian is a classic example—it has traditionally been defined by the extinction of olenellid and redlichiid trilobites and the appearance of paradoxidid trilobites. Here we integrate the global biostratigraphy of these three trilobite groups with high-precision tuff and tandem detrital zircon U-Pb age constraints to falsify prior models for global synchronicity of these events. For the first time, we demonstrate that olenellid trilobites in Laurentia went extinct at least 3 Ma after the first appearance of paradoxidids in Avalonia and West Gondwana (ca. 509 Ma). They also disappeared before the extinction of redlichiids and prior to the base of the Miaolingian at ca. 506 Ma in South China. This indicates that these three trilobite groups (paradoxidids, olenellids, and redlichiids) and their associated biotas overlapped in time for nearly 40% of Cambrian Epoch 2, Age 4. Implications of this chronological overlap are: (1) trilobite transitions were progressive and geographically mediated rather than globally synchronous; and (2) paleontological databases underestimate the diversity of the early Cambrian. This ∼3 Ma diachroneity, at a critical time in the early evolution of animals, also impacts chemostratigraphic and paleoclimatic data sets that are tied to trilobite biostratigraphy and that collectively underpin our understanding of the Cambrian Earth system.

New material of three-dimensionally phosphatized and microscopic cycloneuralians from the Cambrian Paibian Stage of South China

2017 ◽  
Vol 92 (1) ◽  
pp. 87-98 ◽  
Author(s):  
Yunhuan Liu ◽  
Qi Wang ◽  
Tiequan Shao ◽  
Huaqiao Zhang ◽  
Jiachen Qin ◽  
...  
Keyword(s):  
New Species ◽  
South China ◽  
Early Cambrian ◽  
Late Cambrian ◽  
New Material ◽  
Western Hunan ◽  
Fossil Embryos

AbstractSome rare microscopic cycloneuralians are present in the Cambrian of South China, represented by Eopriapulites and Eokinorhynchus (both early Cambrian), fossil embryos of Markuelia (middle to late Cambrian), and palaeoscolecids (early to late Cambrian). Among them, palaeoscolecids are relatively diverse and abundant. Here, we describe new material of three-dimensionally phosphatized and microscopic cycloneuralians from the Paibian Stage of Wangcun Lagerstätte, western Hunan, South China. New material includes fossil embryos assignable to Markuelia sp., two other types of fossil embryos, and three species of palaeoscolecids, including Dispinoscolex decorus Duan, Dong, and Donoghue, 2012, Schistoscolex hunanensis Duan, Dong, and Donoghue, 2012, and Austroscolex sinensis new species. The palaeoscolecid fragments differ mainly in size and armor of the trunk annuli. Since Eokinorhynchus and Eopriapulites occurred the earliest among the Cambrian cycloneuralians, it is proposed here that: (1) cycloneuralians originated in the Cambrian Fortunian small shelly faunas rather than in the early Cambrian macrobenthos, (2) ancestral cycloneuralians may have simple trunk armor, and (3) Eopriapulites represents an ancestral cycloneuralian.

Early Cambrian palaeoscolecid cuticles from Shaanxi, China

1996 ◽  
Vol 70 (2) ◽  
pp. 275-279 ◽  
Author(s):  
Xi-Guang Zhang ◽  
Brian R. Pratt
Keyword(s):  
New Species ◽  
Geographic Distribution ◽  
Lower Cambrian ◽  
New Genus ◽  
Three Dimensional ◽  
Early Cambrian ◽  
Middle Cambrian ◽  
High Diversity

Phosphatized, three-dimensional cuticle fragments of the palaeoscolecids Houscolex lepidotus new genus and new species, Houscolex species indeterminate, and an unidentified form are described from the Lower Cambrian Qiongzhusi Formation of Shaanxi, China. These segmented worms, characterized by regularly arranged simple plates and platelets, small circular pores and fine pits, and irregularly distributed nipplelike protuberances, are unique among known palaeoscolecids. The occurrence of such cuticles as seemingly persistent elements of phosphatized faunas suggests that wormlike organisms achieved a fairly high diversity and widespread geographic distribution during the Early and Middle Cambrian.

Morphological assessment of the earliest paradoxidid trilobites (Cambrian Series 3) from Morocco and Spain

2017 ◽  
Vol 155 (7) ◽  
pp. 1566-1595 ◽  
Author(s):  
J. JAVIER ÁLVARO ◽  
JORGE ESTEVE ◽  
SAMUEL ZAMORA
Keyword(s):  
New Species ◽  
Statistical Analysis ◽  
Iberian Peninsula ◽  
Linear Measurement ◽  
Geometric Morphometric ◽  
Middle Cambrian ◽  
West Gondwana ◽  
Regional Correlation ◽  
Definition Of ◽  
Morphological Assessment

AbstractA Cambrian immigration event of paradoxidid trilobites has traditionally marked some regional lower–middle Cambrian boundaries in the Acado-Baltic subprovince (including Baltica and the Mediterranean and Avalonian margins of West Gondwana). The earliest paradoxidine species in Morocco and the Iberian Peninsula have been used as a chronostratigraphic link to support the definition of a common base for the Cambrian Series 3, but recent studies have proposed new species without revising previously established ones. This paper offers a morphological statistical analysis based on both linear measurement and landmark-based geometric morphometric approaches performed on the earliest paradoxinine trilobites sampled in the Anti-Atlas (Morocco) and the Iberian Chains (Spain). As a result, the diagnosis of Acadoparadoxides mureroensis is emended and several species recently erected in Morocco (A. cf. mureroensis, A. levisettii, A. ovatopyge and A. pampalius) are suggested as synonyms of A. mureroensis until 3D statistical analyses are available based on material preserved on carbonate or silica nodules. The first appearance of A. mureroensis in both areas can be provisionally used for regional correlation until homotaxic tests are checked.

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