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Wyszukujesz frazę "Bengtson, Stefan" wg kryterium: Autor


Wyświetlanie 1-2 z 2
Tytuł:
X-ray tomographic microscopy tightens affinity of the early Cambrian Oymurania to the brachiopod stem group
Autorzy:
KOUCHINSKY, ARTEM
BENGTSON, STEFAN
Powiązania:
https://bibliotekanauki.pl/articles/945372.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Opis:
The geologically rapid biotic evolution in the early Cambrian is marked by the first appearance of major groups of animals in the fossil record (e.g., Budd and Jensen 2000; Kouchinsky et al. 2012). Along with the earliest crown-group representatives of the phylum Brachiopoda, more basal branches of the phylogenetic tree belonging to the stem-group Brachiopoda, such as tannuolinids and mikwitziids, diversified and became widespread during the early Cambrian (e.g., Williams and Holmer 2002; Balthasar et al. 2009; Skovsted et al. 2014). Synchrotron-radiation X-ray tomographic microscopy (SRXTM) of Oymurania gravestocki reveals the microstructure of its calcium-phosphatic shell differentiated into two layers and intersecting systems of canals. The outer layer shows the acrotretoid columnar microstructure and the inner layer consists of continuous prismatic columns. Phosphatized setae preserved within tangential canals, as well as perpendicular canals of Micrina–Setatella type demonstrate homology with the tannuolinid Micrina and the mickwitziid Setatella. A unique and novel combination of microstructural features in Oymurania confirms its evolutionary position within the brachiopod stem group.
Źródło:
Acta Palaeontologica Polonica; 2017, 62, 1; 39-43
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Terreneuvian stratigraphy and faunas from the Anabar Uplift, Siberia
Autorzy:
Kouchinsky, Artem
Bengtson, Stefan
Landing, Ed
Steiner, Michael
Vendrasco, Michael
Ziegler, Karen
Powiązania:
https://bibliotekanauki.pl/articles/945221.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
mollusca
small shelly fossils
stratigraphy
carbon isotopes
cambrian
terreneuvian
russia
siberia
anabar
Opis:
Assemblages of mineralized skeletal fossils are described from limestone rocks of the lower Cambrian Nemakit-Daldyn, Medvezhya, Kugda-Yuryakh, Manykay, and lower Emyaksin formations exposed on the western and eastern flanks of the Anabar Uplift of the northern Siberian Platform. The skeletal fossil assemblages consist mainly of anabaritids, molluscs, and hyoliths, and also contain other taxa such as Blastulospongia, Chancelloria, Fomitchella, Hyolithellus, Platysolenites, Protohertzina, and Tianzhushanella. The first tianzhushanellids from Siberia, including Tianzhushanella tolli sp. nov., are described. The morphological variation of Protohertzina anabarica and Anabarites trisulcatus from their type locality is documented. Prominent longitudinal keels in the anabaritid Selindeochrea tripartita are demonstrated. Among the earliest molluscs from the Nemakit-Daldyn Formation, Purella and Yunnanopleura are interpreted as shelly parts of the same species. Fibrous microstructure of the outer layer and a wrinkled inner layer of mineralised cuticle in the organophosphatic sclerites of Fomitchella are reported. A siliceous composition of the globular fossil Blastulospongia is reported herein and a possible protistan affinity similar to Platysolenites is discussed. New carbon isotope data facilitate correlation both across the Anabar Uplift and with the Terreneuvian Series of the IUGS chronostratigraphical scheme for the Cambrian System. The base of Cambrian Stage 2 is provisionally placed herein within the Fortunian‒Cambrian Stage 2 transitional interval bracketed by the lowest appearance of Watsonella crosbyi and by a slightly higher horizon at the peak of carbon isotope excursion Iʹ from western flank of the Anabar Uplift. Correlation across the Siberian Platform of the fossiliferous Medvezhya and lower Emyaksin formations showing δ¹³C carb excursion Iʹ with the upper Sukharikha Formation containing excursion 5p and upper Ust’-Yudoma Formation containing excursion I is supported herein.
Źródło:
Acta Palaeontologica Polonica; 2017, 62, 2; 311-440
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
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