Temat: skeletal fossil - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: New finds of skeletal fossils in the terminal Neoproterozoic of the Siberian Platform and Spain
Autorzy:: Zhuravlev, A.Y.
Linan, E.
Gamez Vintaned, J.A.
Debrenne, F.
Fedorov, A.B.
Tematy:: skeletal fossil
Neoproterozoic
Siberian Platform
Spain
Cloudina
Ediacaran skeletal fossil
microstructure
extinction; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Paleobiologii PAN
Powiązania:: https://bibliotekanauki.pl/articles/22120.pdf Link otwiera się w nowym oknie
Opis:: A current paradigm accepts the presence of weakly biomineralized animals only, barely above a low metazoan grade of organization in the terminal Neoproterozoic (Ediacaran), and a later, early Cambrian burst of well skeletonized animals. Here we report new assemblages of primarily calcareous shelly fossils from upper Ediacaran (553–542 Ma) carbonates of Spain and Russia (Siberian Platform). The problematic organism Cloudina is found in the Yudoma Group of the southeastern Siberian Platform and different skeletal taxa have been discovered in the terminal Neoproterozoic of several provinces of Spain. New data on the morphology and microstructure of Ediacaran skeletal fossils Cloudina and Namacalathus indicate that the Neoproterozoic skeletal organisms were already reasonably advanced. In total, at least 15 skeletal metazoan genera are recorded worldwide within this interval. This number is comparable with that known for the basal early Cambrian. These data reveal that the terminal Neoproterozoic skeletal bloom was a real precursor of the Cambrian radiation. Cloudina, the oldest animal with a mineralised skeleton on the Siberian Platform, characterises the uppermost Ediacaran strata of the Ust’−Yudoma Formation. While in Siberia Cloudina co−occurs with small skeletal fossils of Cambrian aspect, in Spain Cloudina−bearing carbonates and other Ediacaran skeletal fossils alternate with strata containing rich terminal Neoproterozoic trace fossil assemblages. These finds treated together provide a possibility to correlate transitional Neoproterozoic– lower Cambrian strata around the world. Such a correlation concurs with available isotope and radiometric data and indicates that typical Ediacaran shelly fossils have not crossed the Precambrian–Cambrian boundary.
Dostawca treści:: Biblioteka Nauki

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Tytuł:: Shell microstructures in Early Cambrian molluscs
Autorzy:: Kouchinsky, A
Tematy:: skeletal fossil
microstructure
shell
biomineralization
mollusc
Early Cambrian
mollusc-like organism
taxonomy
Cambrian
paleontology; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Paleobiologii PAN
Powiązania:: https://bibliotekanauki.pl/articles/23294.pdf Link otwiera się w nowym oknie
Opis:: The affinities of a considerable part of the earliest skeletal fossils are problematical, but investigation of their microstructures may be useful for understanding biomineralization mechanisms in early metazoans and helpful for their taxonomy. The skeletons of Early Cambrian mollusc-like organisms increased by marginal secretion of new growth lamellae or sclerites, the recognized basal elements of which were fibers of apparently aragonite. The juvenile part of some composite shells consisted of needle-like sclerites; the adult part was built of hollow leaf-like sclerites. A layer of mineralized prism-like units (low aragonitic prisms or flattened spherulites) surrounded by an organic matrix possibly existed in most of the shells with continuous walls. The distribution of initial points of the prism-like units on a periostracurn-like sheet and their growth rate were mostly regular. The units may be replicated on the surface of internal molds as shallow concave polygons, which may contain a more or less well-expressed tubercle in their center. Tubercles are often not enclosed in concave polygons and may co-occur with other types of textures. Convex polygons seem to have resulted from decalcification of prism-like units. They do not co-occur with tubercles. The latter are interpreted as casts of pore channels in the wall possibly playing a role in biomineralization or pits serving as attachment sites of groups of mantle cells. Casts of fibers and/or lamellar units may overlap a polygonal texture or occur without it. They may reflect an inner layer consisting of aragonitic fibers fused into more or less well-developed lamellar units. It seems that nacreous and crossed-lamellar aragonitic microstructures evolved in the Cambrian from such lamellar aragonitic microstructures independently in different groups of molluscs.
Dostawca treści:: Biblioteka Nauki

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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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Tytuł:: The hind limb skeleton and cursorial adaptations of the Plio-Pleistocene rabbit Hypolagus beremendensis
Autorzy:: Fostowicz-Frelik, L
Tematy:: paleoecological analysis
Plio-Pleistocene
Hypolagus beremendensis
Polska
Lagomorpha
fossil
Leporidae
hindlimb
skeletal remains
Europe
rabbit
paleontology
Pliocene
functional morphology; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Paleobiologii PAN
Powiązania:: https://bibliotekanauki.pl/articles/21207.pdf Link otwiera się w nowym oknie
Opis:: Hypolagus beremendensis, a representative of the Archaeolaginae, was one of the most abundant and widespread leporids in the Plio−Pleistocene of Europe. The vast accumulations of skeletal remains from the Polish Pliocene sites (Węże 1, Rębielice Królewskie 1 and 2, and Kadzielnia 1) yielded thousands of bones representing almost all skeletal regions. The detailed hind limb morphology of Hypolagus beremendensisis presented in comparison with five extant leporids (Lepus europaeus, Oryctolagus cuniculus, Pentalagus furnessi, Sylvilagus floridanus, and S. brasiliensis), which represent a wide range of locomotor adaptations. The UPGMA analysis of 98 metric characters places Hypolagus beremendensis next to the leporine rabbits. Hypolagus beremendensis has the os coxae, femur, and talus most similar to P. furnessi, tibia and calcaneus to the leporine rabbits, and the structure of foot to Lepus. The elongation of the foot and tibiofibular segment in relation to the femur indicates an advanced cursorial adaptation and a relatively steep jump. The similarities in the proximal segments (os coxae and femur) between Hypolagus and Pentalagus highlight the conservative morphology of this region in the Leporidae.
Dostawca treści:: Biblioteka Nauki

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