Earliest skeletal fossils from Precambrian–Cambrian boundary strata, Elburz Mountains, Iran

1989 ◽  
Vol 126 (3) ◽  
pp. 283-289 ◽  
Author(s):  
B. Hamdi ◽  
M. D. Brasier ◽  
Jiang Zhiwen
Keyword(s):  
Central Asia ◽  
South China ◽  
Siberian Platform ◽  
Early Cambrian ◽  
Late Precambrian

AbstractThe lithological and biotic succession across the late Precambrian to early Cambrian interval is outlined for the Dalir and Valiabad successions of the Elburz Mountains of Iran. The Lower Dolomite Member contains an assemblage of phosphatic tubes and other poorly preserved remains. The succeeding Lower Shale Member bears macroscopic chuariamorphid algae. Early skeletal fossil diversity rises through the Middle Dolomite Member, with the successive appearance ofProtohertzina anabarica, Cambrotubulus decurvatusandAnabarites trisulcatus, culminating near the top of the dolomites with the appearance ofPurellasp.,Maikhanella multa, Tiksitheca licisand circothecids. This succession is compared with lower to upper parts of the Nemakit-Daldyn Formation of Siberia. The overlying Upper Shale Member bears phosphatic beds at its base with allathecids and an uncoiled pelagiellid (?Aldanellasp.) that suggest comparison with lower Tommotian strata and the Precambrian–Cambrian boundary phosphorite event of southern and central Asia. A rich assemblage of molluscs appears high in the Upper Shale Member, including theLatouchella korobkovigroup and thePelagiella lorenzigroup. The succession is broadly homotaxial with those from the Siberian Platform and Mongolia and those platforms bordering Gondwana (India, Kazakhstan, South China).

The oldest sequence of skeletal fossils in the Lower Cambrian of southeastern Newfoundland

1983 ◽  
Vol 20 (4) ◽  
pp. 525-536 ◽  
Author(s):  
Stefan Bengtson ◽  
Terence P. Fletcher
Keyword(s):  
Siberian Platform ◽  
Lower Cambrian ◽  
Short Interval ◽  
Time Span ◽  
Early Cambrian ◽  
Late Precambrian ◽  
Complete Sequences ◽  
Continuous Sedimentation

Sections on the Burin Peninsula in southeastern Newfoundland show a record of continuous sedimentation during the Late Precambrian–Early Cambrian transition. These may be correlated lithologically and biostratigraphically with less complete sequences on the Avalon and Bonavista Peninsulas. Below the oldest known trilobites in southeastern Newfoundland (of the Callavia Zone) two consecutive assemblages of skeletal fossils are recognizable: an Aldanella attleborensis assemblage and the succeeding Coleoloides typicalis assemblage. The shift between the two assemblages takes place within the Bonavista Formation in the Avalon–Bonavista region and in a similar succession of mudstones near St. Lawrence on the Burin Peninsula. The quartzitic Random Formation appears to have been deposited during a short interval within the time span represented by the A. attleborensis assemblage, and there is no conclusive biostratigraphical evidence of any major diachronism of this unit. The A. attleborensis assemblage contains taxa known from the lower part of the Tommotian Stage on the Siberian Platform. It is interpreted to be of Tommotian age, and the subsequent shift to the C. typicalis assemblage is tentatively correlated with the Tommotian–Atdabanian boundary as recognized in Siberia.

Late Precambrian–Early Cambrian stratigraphic and faunal succession of eastern California and the Precambrian–Cambrian boundary

1978 ◽  
Vol 115 (2) ◽  
pp. 121-126 ◽  
Author(s):  
C. A. Nelson
Keyword(s):  
Siberian Platform ◽  
Death Valley ◽  
Early Cambrian ◽  
Late Precambrian ◽  
Faunal Succession

SummaryThe Late Precambrian and Early Cambrian strata in eastern California and Nevada can be divided into 3 facies – the eastern Craton, the White-Inyo, and the Death Valley. These 3 facies supply evidence of 3 trilobite zones – the Fallotaspis, the Nevadella and the Bonnia-Olenellus; the inter-relationships are outlined. Correlations with the Siberian Platform successions are discussed and the Precambrian–Cambrian boundary is tentatively placed within the beds of the upper Reed Dolomite in the White-lnyo Range.

A New Platy-armored Worm from the Early Cambrian Chengjiang Lagerstätte, South China

2010 ◽  
Vol 77 (1) ◽  
pp. 1-6 ◽  
Author(s):  
HAN Jian ◽  
ZHANG Xingliang ◽  
ZHANG Zhifei ◽  
SHU Degan
Keyword(s):  
South China ◽  
Early Cambrian ◽  
Chengjiang Lagerstätte

Shift in limiting nutrients in the late Ediacaran–early Cambrian marine systems of South China

2019 ◽  
Vol 530 ◽  
pp. 281-299 ◽  
Author(s):  
Manabu Nishizawa ◽  
Yuki Tsuchiya ◽  
Wei Du ◽  
Yusuke Sawaki ◽  
Yohei Matsui ◽  
...  
Keyword(s):  
South China ◽  
Early Cambrian ◽  
Marine Systems ◽  
Limiting Nutrients

scholarly journals Evaluating episodic hydrothermal activity in South China during the early Cambrian: Implications for biotic evolution

2020 ◽  
Vol 117 ◽  
pp. 104355 ◽  
Author(s):  
Zhanghu Wang ◽  
Jingqiang Tan ◽  
Richard Boyle ◽  
Jason Hilton ◽  
Zhongliang Ma ◽  
...  
Keyword(s):  
South China ◽  
Hydrothermal Activity ◽  
Early Cambrian

scholarly journals A problematic animal fossil from the early Cambrian Hetang Formation, South China—A reply

2019 ◽  
Vol 93 (06) ◽  
pp. 1279-1282 ◽  
Author(s):  
Qing Tang ◽  
Jie Hu ◽  
Guwei Xie ◽  
Xunlai Yuan ◽  
Bin Wan ◽  
...  
Keyword(s):  
South China ◽  
Early Cambrian ◽  
Taxonomic Identification

AbstractWe recently reported Cambrowania ovata Tang and Xiao in Tang et al., 2019, from the early Cambrian Hetang Formation in South China and interpreted it as a problematic animal fossil, possibly related to either sponges or bivalved arthropods (Tang et al., 2019). Slater and Budd (2019) contested our taxonomic identification and phylogenetic interpretation; instead, they claimed that Cambrowania ovata is a large acritarch referable to morphotaxon Leiosphaeridia Eisenack, 1958, and thus is not an animal. Here we refute their criticisms, clarify the differences between Cambrowania and Leiosphaeridia and other acritarchs, and reiterate why an animal affinity for Cambrowania cannot be ruled out.

scholarly journals Fossils from South China redefine the ancestral euarthropod body plan

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Cédric Aria ◽  
Fangchen Zhao ◽  
Han Zeng ◽  
Jin Guo ◽  
Maoyan Zhu
Keyword(s):  
South China ◽  
Phenotypic Variability ◽  
Morphological Diversity ◽  
Body Plan ◽  
External Morphology ◽  
Evidence Based ◽  
Early Cambrian ◽  
Neural Tissues ◽  
The Common ◽  
Bayesian Phylogeny

Abstract Background Early Cambrian Lagerstätten from China have greatly enriched our perspective on the early evolution of animals, particularly arthropods. However, recent studies have shown that many of these early fossil arthropods were more derived than previously thought, casting uncertainty on the ancestral euarthropod body plan. In addition, evidence from fossilized neural tissues conflicts with external morphology, in particular regarding the homology of the frontalmost appendage. Results Here we redescribe the multisegmented megacheirans Fortiforceps and Jianfengia and describe Sklerolibyon maomima gen. et sp. nov., which we place in Jianfengiidae, fam. nov. (in Megacheira, emended). We find that jianfengiids show high morphological diversity among megacheirans, both in trunk ornamentation and head anatomy, which encompasses from 2 to 4 post-frontal appendage pairs. These taxa are also characterized by elongate podomeres likely forming seven-segmented endopods, which were misinterpreted in their original descriptions. Plesiomorphic traits also clarify their connection with more ancestral taxa. The structure and position of the “great appendages” relative to likely sensory antero-medial protrusions, as well as the presence of optic peduncles and sclerites, point to an overall homology with the anterior head of radiodontans. This is confirmed by our Bayesian phylogeny, which places jianfengiids as the basalmost euarthropods, paraphyletic with other megacheirans, and in contiguity with isoxyids and radiodontans. Conclusions Sklerolibyon and other jianfengiids expand the disparity of megacheirans and suggest that the common euarthropod ancestor possessed a remarkable phenotypic variability associated with the externalized cephalon, as well as endopods that were already heptopodomerous, which differs from previous hypotheses and observations. These animals also demonstrate that the frontalmost pair of arthrodized appendage is homologous between radiodontans and megacheirans, refuting the claim that the radiodontan frontal appendages evolved into the euarthropod labrum, and questioning its protocerebral identity. This evidence based on external anatomy now constitutes a solid benchmark upon which we should address issues of homology, with the help of carefully examined palaeoneurological data.

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