Temat: Middle Cambrian - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Sphenothallus Hall, 1847 from Cambrian of Skryje–Týřovice Basin (Barrandian area, Czech Republic)
Autorzy:: Fatka, O.
Kraft, P.
Tematy:: Sphenothallus
middle Cambrian
Buchava Formation
Barrandian area Czech Republic; Pokaż więcej
Wydawca:: Polskie Towarzystwo Geologiczne
Powiązania:: https://bibliotekanauki.pl/articles/191806.pdf Link otwiera się w nowym oknie
Opis:: Two conical tubules from shales of the Skryje Member (Buchava Formation) at the Skryje–Luh and Týřovice–“Pod hruškou” localities, two of the key outcrops of this stratigraphic unit in the Skryje–Týřovice Basin (Barrandian area, Czech Republic), are described. One specimen consists of a small, compressed tubule with a very low expansion angle and wide and flat thickenings. The second, larger specimen exhibits indications of very narrow thickenings of a more abruptly expanding shell. Both specimens are assigned to the genus Sphenothallus Hall, but the latter only provisionally. Sphenothallus shows a worldwide distribution with numerous species, ranging from Cambrian to Permian in age. However, reported occurrences in the Cambrian are relatively sparse, in the form of rare specimens from the lower to middle Cambrian strata of Laurentia, Eastern Gondwana and European peri-Gondwana. According to accepted palaeogeographical reconstructions, Cambrian Sphenothallus occurred in low as well as in higher palaeolatitudes.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: The Burges Shale animal Oesia is not a chaetognath: A reply to Szaniawski [2005]
Autorzy:: Morris, S C
Tematy:: discussion
paleontology
Middle Cambrian
Burges Shale
Oesia disjuncta
chaetognath; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Paleobiologii PAN
Powiązania:: https://bibliotekanauki.pl/articles/21841.pdf Link otwiera się w nowym oknie
Opis:: The Middle Cambrian Oesia disjuncta, a monospecific genus, is known only from the celebrated Burgess Shale of British Columbia. It has been re−interpreted by Szaniawski (Acta Palaeontologica Polonica 50:1–8; 2005) as a chaetognath, a distinctive phylum whose exact position in the protostomes is still controversial. Unequivocal chaetognaths, that have no similarity to Oesia, are already known to occur in the Chengjiang Lagerstätte (Lower Cambrian, S.W. China), and here I describe the first example of a chaetognath from the Burgess Shale itself. Comparisons between Oesia and chaetognaths fail to find any significant homologies. Whilst the phyletic position of Oesia is very uncertain, a place in the hemichordates may be worth exploring.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Burgess Shale-type microfossils from the middle Cambrian Kaili Formation, Guizhou Province, China
Autorzy:: Harvey, T.H.P.
Ortega-Hernandez, J.
Lin, J.-P.
Yuanlong, Z.
Butterfield, N.J.
Tematy:: paleontology
microfossil
Middle Cambrian
Cambrian
Kaili Formation
Guizhou province
China
Priapulida
acritarch
palynology
taphonomy; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Paleobiologii PAN
Powiązania:: https://bibliotekanauki.pl/articles/23425.pdf Link otwiera się w nowym oknie
Opis:: Diverse carbonaceous microfossils, including exceptionally preserved remains of non−biomineralizing metazoans, are reported from a basal middle Cambrian interval of the Kaili Formation (Guizhou Province, China). The application of a gentle acid maceration technique complements previous palynological studies by revealing a larger size−class of acritarchs, a richer assemblage of filamentous microfossils, and a variety of previously unrecovered forms. Metazoan fossils include Wiwaxia sclerites and elements derived from biomineralizing taxa, including chancelloriids, brachiopods and hyolithids, in common with previously studied assemblages from the early and middle Cambrian of Canada. In addition, the Kaili Formation has yielded pterobranch remains and an assemblage of cuticle fragments representing “soft−bodied” worms, including a priapulid−like scalidophoran. Our results demonstrate the wide distribution and palaeobiological importance of microscopic “Burgess Shale−type” fossils, and provide insights into the limitations and potential of this largely untapped preservational mode.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Slope failure on a Cambrian carbonate platform, mass-flow transitions and resulting complex deposit
Autorzy:: Wang, Zhaopeng
Liu, Jiaye
Van Loon, A. J. (Tom)
Zhu, Decheng
Qin, Peng
Han, Zuozhen
Tematy:: Gushan Formation
Middle Cambrian
epeiric sea
carbonate platform
mass-flow transitions; Pokaż więcej
Wydawca:: Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Powiązania:: https://bibliotekanauki.pl/articles/2058558.pdf Link otwiera się w nowym oknie
Opis:: The quiet environment of the carbonate platform in the epeiric sea that existed during the Cambrian between present-day China and Korea was occasionally affected by processes that have hitherto not been described from such a setting. A conglomerate was found in the Middle Cambrian Gushan Formation near Chengouwan (Shandong Province, E China), eroded into the underlying sediments. The conglomerate is explained as a deposit consisting of material that was eroded up-slope when slope-failure took place, resulting in a slump that passed into a high-density debris flow with erosive power that passed, in turn, again into a slump. The slump came to rest when it lost its momentum on a less inclined part of the basin slope. Immediately after deposition, fluidization occurred in the lower part of the slump deposit, as proven by a funnel-shaped water-escape structure and a lateral injection of some metres long of brecciated material.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Cambrian microfossils from glacial erratics of King George Island, Antarctica
Autorzy:: Wrona, R
Tematy:: skeletal fossil
Antarctic
Australia
Middle Cambrian
Early Cambrian
microfossil
Cape Melville Formation
Cambrian
paleontology
Early Miocene
King George Island; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Paleobiologii PAN
Powiązania:: https://bibliotekanauki.pl/articles/22565.pdf Link otwiera się w nowym oknie
Opis:: Limestone erratics in the Early Miocene glacio−marine Cape Melville Formation of King George Island, West Antarctica, have yielded Early and Middle Cambrian small skeletal fossils (SSF) accompanied by calcified cyanobacteria, archaeocyath and spiculate sponges, trilobites and echinoderms. The SSF assemblage comprises disarticulated sclerites of chancelloriids, halkieriids, tommotiids, lapworthellids, palaeoscolecids, hyolithelminths, lingulate brachiopods, helcionelloid molluscs, hyoliths, and bradoriids. All 24 described species are common to Antarctica and Australia. Most are recorded here from Antarctica for the first time, including Shetlandia multiplicata gen. et sp. nov. and two new species Byronia? bifida and Hadimopanella staurata. The lithological and fossil contents of the boulders are almost identical with autochthonous assemblages from the Shackleton Limestone in the Argentina Range and Transantarctic Mountains. Cambrian outcrops around the Weddell Sea are a plausible source of the erratics. The fauna is closely similar to that from the uppermost Botomian Wilkawillina Limestone in the Flinders Ranges and Parara Limestone on Yorke Peninsula, and Toyonian Wirrealpa and Aroona Creek Limestones in the Flinders Ranges, as well as the Ramsay Limestone on Yorke Peninsula, all in the Arrowie and Stansbury Basins of South Australia. These very similar faunal and facies successions for Antarctica and Australia strongly support their common biotic and sedimentary evolution on the same margin of a greater Gondwana supercontinent throughout the Early Cambrian.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Soft-part preservation in two species of the arthropod Isoxys from the middle Cambrian Burgess Shale of British Columbia, Canada
Autorzy:: Garcia-Bellido, D.C.
Vannier, J.
Collins, D.
Tematy:: arthropod
Isoxys
Middle Cambrian
Cambrian
Burgess Shale
British Columbia
Canada
Arthropoda
Isoxys acutangulus
Isoxys longissimus
paleontology
fossil; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Paleobiologii PAN
Powiązania:: https://bibliotekanauki.pl/articles/20887.pdf Link otwiera się w nowym oknie
Opis:: More than forty specimens from the middle Cambrian Burgess Shale reveal the detailed anatomy of Isoxys, a worldwide distributed bivalved arthropod represented here by two species, namely Isoxys acutangulus and Isoxys longissimus. I. acutangulus had a non−mineralized headshield with lateral pleural folds (= “valves” of previous authors) that covered the animal’s body almost entirely, large frontal spherical eyes and a pair of uniramous prehensile appendages bearing stout spiny outgrowths along their anterior margins. The 13 following appendages had a uniform biramous design—i.e., a short endopod and a paddle−like exopod fringed with marginal setae with a probable natatory function. The trunk ended with a flap−like telson that protruded beyond the posterior margin of the headshield. The gut of I. acutangulus was tube−like, running from mouth to telson, and was flanked with numerous 3D−preserved bulbous, paired features interpreted as digestive glands. The appendage design of I. acutangulus indicates that the animal was a swimmer and a visual predator living off−bottom. The general anatomy of Isoxys longissimus was similar to that of I. acutangulus although less information is available on the exact shape of its appendages and visual organs. I. longissimus is characterized by extremely long anterior and posterior spines. There are now seven Isoxys species known with soft−part preservation, I. acutangulus, I. longissimus from the Burgess Shale, I. auritus and I. curvirostratus from the Maotianshan Shale of China, I. communis and I. glaessneri from the Emu Bay Shale of Australia and I. volucrisfrom Sirius Passet in Greenland. The frontal appendages of Isoxys strongly resemble those of other Cambrian arthropods, characterized by a single pair of “great appendages” with a shared prehensile function yet some variability in length and shape.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Fossil chaetognaths from the Burgess Shale: A reply to Conway Morris [2009]
Autorzy:: Szaniawski, H
Tematy:: paleontology
chaetognath
fossil
new genus
new species
Middle Cambrian
Chaetognatha
Oesia disjuncta
polychaete annelid
Cambrian
Amiskwia sagittiformis; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Paleobiologii PAN
Powiązania:: https://bibliotekanauki.pl/articles/21244.pdf Link otwiera się w nowym oknie
Opis:: Walcott (1911) erected the new genus and species Oesia disjuncta and assigned them to the polychaete annelids, based on a small collection of similar fossils from the famous Middle Cambrian Burgess Shale. In 2002 I suggested that the species is “possibly related to chaetognaths” (Szaniawski 2002: 405). Later, after obtaining new photos of the specimens and making comparative investigations with the extant chaetognaths, I was able to describe many significant similarities, and came to the conclusion that O. disjuncta indeed is an ancestral chaetognath (Szaniawski 2005). This interpretation already has been accepted in several publications (Vannier et al. 2005; Ball and Miller 2006; Hu et al. 2007. Giribet 2008). Ball and Miller (2006: 594) confirmed not only its “... remarkable resemblance to modern chaetognaths” but also correctness of recognition of all its organs. They even reproduced a part of my illustration showing them (Ball and Miller 2006: fig. 2). Vannier et al. (2006: 629) combined the problem with the open question of the systematic position of another Burgess Shale fossil Amiskwia sagittiformis Walcott, 1911, and expressed their reservation based on “...the lack of clear evidence of a grasping apparatus...”. Only Conway Morris (2009) firmly disagreed with this diagnosis and even devoted a special “discussion” article addressing the issue. However, that article contains several ambiguities and misunderstandings which need clarification.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Skeletonized microfossils from the Lower-Middle Cambrian transition of the Cantabrian Mountains, Northern Spain
Autorzy:: Clausen, S
Alvaro, J.J.
Tematy:: hyolith
cambroclavid
benthic replacement
microfossil
skeletonized microfossil
Spain
hyoliththelminth
sponge
chancelloriid
Cambrian
paleontology
Cantabrian Mountains
Lower-Middle Cambrian; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Paleobiologii PAN
Powiązania:: https://bibliotekanauki.pl/articles/21794.pdf Link otwiera się w nowym oknie
Opis:: Two different assemblages of skeletonized microfossils are recorded in bioclastic shoals that cross the Lower–Middle Cambrian boundary in the Esla nappe, Cantabrian Mountains. The uppermost Lower Cambrian sedimentary rocks represent a ramp with ooid−bioclastic shoals that allowed development of protected archaeocyathan−microbial reefs. The shoals yield abundant debris of tube−shelled microfossils, such as hyoliths and hyolithelminths (Torellella), and trilobites. The overlying erosive unconformity marks the disappearance of archaeocyaths and the Iberian Lower–Middle Cambrian boundary. A different assemblage occurs in the overlying glauconitic limestone associated with development of widespread low−relief bioclastic shoals. Their lowermost part is rich in hyoliths, hexactinellid, and heteractinid sponge spicules (Eiffelia), chancelloriid sclerites (at least six form species of Allonnia, Archiasterella, and Chancelloria), cambroclaves (Parazhijinites), probable eoconchariids (Cantabria labyrinthica gen. et sp. nov.), sclerites of uncertain affinity (Holoplicatella margarita gen. et sp. nov.), echinoderm ossicles and trilobites. Although both bioclastic shoal complexes represent similar high−energy conditions, the unconformity at the Lower–Middle Cambrian boundary marks a drastic replacement of microfossil assemblages. This change may represent a real community replacement from hyolithelminth−phosphatic tubular shells to CES (chancelloriid−echinoderm−sponge) meadows. This replacement coincides with the immigration event based on trilobites previously reported across the boundary, although the partial information available from originally carbonate skeletons is also affected by taphonomic bias.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Rugosa and Scleractinia - a commentary on some methods of phylogenetic reconstructions
Autorzy:: Fedorowski, J
Tematy:: Rugosa
similarity
Scleractinia
Calceola sandalina
Cothonion sympomatum
morphology
external wall
mineralogy
stratigraphy
Middle Cambrian
evolution
paleontology
calice rim; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Paleobiologii PAN
Powiązania:: https://bibliotekanauki.pl/articles/21231.pdf Link otwiera się w nowym oknie
Opis:: The origin of the Rugosa and relationships between the Rugosa and Scleractinia are debated. In the present account I comment on some recently published phylogenetic reconstructions, which in my opinion, are based on inadequate data.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: A new Middle Cambrian stem-group echinoderm from Spain: Palaeobiological implications of a highly asymmetric cinctan
Autorzy:: Zamora, S
Smith, A.B.
Tematy:: paleobiology
new species
Homostelea
Spain
paleontology
Echinodermata
functional morphology
asymmetric body
Middle Cambrian
echinoderm
Lignanicystis barriosensis
carpoid; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Paleobiologii PAN
Powiązania:: https://bibliotekanauki.pl/articles/22838.pdf Link otwiera się w nowym oknie
Opis:: A new exquisitely preserved stem group echinoderm (cinctan), Lignanicystis barriosensis gen. et sp. nov., is described from the Middle Cambrian of Los Barrios de Luna, North Spain. This displays a unique asymmetrical body plan with ventral projecting nodes that raised the lower surface above the substratum. There are four openings through the body wall: mouth, anus, atrium, and an aligned row of sutural pores of uncertain function. Unlike other cinctans, Lignanicystis has a strongly asymmetrical shape convergent with that of some cornute carpoids. Like cornutes, the test is also elevated above the substratum to allow water flow beneath the theca. In both cases this is probably an adaptation to life in higher water flow regimes.
Dostawca treści:: Biblioteka Nauki

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