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Wyszukujesz frazę "fossil shell" wg kryterium: Temat


Wyświetlanie 1-10 z 10
Tytuł:
Phosphate replicated and replaced microstructure of molluscan shells from the earliest Cambrian of China
Autorzy:
Feng, W
Sun, W.
Powiązania:
https://bibliotekanauki.pl/articles/21263.pdf
Data publikacji:
2003
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
microstructure
fossil
shell
biomineralization
Mollusca
China
mollusc
Cambrian
paleontology
Opis:
The earliest Cambrian Meishucunian phosphoritic succession in eastern Yunnan,China,contains well−preserved molluscan shells that offer insights into the early evolution of skeletonization. Phosphate internal moulds,phosphate replaced originally carbonate shells,and phosphate coatings show lamello−fibrillar structure,prismatic structure,and regularly foliated structure. The lamello−fibrillar structure appears earlier in the fossil record than laminar structures such as nacreous or foliated structures. It has been identified in fossil mollusks,which occur in China as early as the lower phosphate layer of the Zhongyicun Member of the Meishucunian. Therefore,the lamello−fibrillar structure appears to be primitive in mollusks. The lamello−fibrillar and prismatic aragonite is the most common shell material of molluscan skeletons in the Early Cambrian Meishucunian and equivalents around the world. Although the early molluscan microstructure is not so diverse as that of extant mollusks,it may be of use in high rank taxonomic classification as shown by the early conchiferan mollusks discussed here. These mollusks are characterized by the horizontal fibrillae that are layered and parallel,and thereby differ from hyoliths,in which the horizontal fibrillae appear to be in the form of the bundles of fibres that can branch or anastomose.
Źródło:
Acta Palaeontologica Polonica; 2003, 48, 1
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
X-ray microtomography (XMT) of fossil brachiopod shell interiors for taxonomy
Autorzy:
Blazejowski, B.
Binkowski, M.
Bitner, M.A.
Gieszcz, P.
Powiązania:
https://bibliotekanauki.pl/articles/23513.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
x-ray microtomography
fossil
brachiopod
shell
taxonomy
remains
paleontology
Terebratula terebratula
Opis:
The ability to see and understand the three−dimensional structure of an investigated object plays a key role in studying fossil remains. All living organisms are formed in threedimensions, but unfortunately fossilization processes often reduce overall shape, making it difficult to gather information about real overall appearance, functionality, and inner structure. Here, using a specimen of the brachiopod Terebratula terebratula we demonstrate a non−destructive technique for exploring the 3−D internal structure of fossil remains. The use of tomography allows the construction of a set of transverse serial sections in the manner used by brachiopod researchers for decades.
Źródło:
Acta Palaeontologica Polonica; 2011, 56, 2
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Classification of fossil eggshells of amniotic vertebrates
Klasyfikacja kopalnych skorup jaj owodniowców
Autorzy:
Mikhailov, K.E.
Powiązania:
https://bibliotekanauki.pl/articles/21891.pdf
Data publikacji:
1991
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
paleontology
fossil
classification
egg shell
amniotic egg
vertebrate
Reptilia
Aves
taxonomy
paleobiology
Opis:
Fossil avian and reptilian eggs and eggshells, from the Cretaceous of Mongolia and USSR (Kazakhstan, Zaisan basin) as well as samples of dinosaurian and the Eocene avian eggshells from USA, China, France and Argentina were studied. Methodological, terminological and biomineralization aspects of eggshell structure are discussed. Considered are different classifications of eggshell according to the structural levels of eggshell matter organization (texture, general histostructure, superficial morphology). Basic types, morphotypes, types of pore system and types of surface ornamentation are the main structural categories employed in the systematic description of fossil material. About 18 groups of fossil eggshells referred to turtles, geckoes, crocodiles, and to 14 “families” or dinosaur and bird oological remains are described. Their composition, occurence, paleobiology and systematics are shortly presented.
Praca zawiera przegląd budowy skorup jaj gadzich i ptasich oraz propozycją ujednoliconej terminologii oologicznej (fig. 1—8, tab. 1—2). Zbadany materiał obejmuje szczątki kredowych i kenozoicznych jaj gadzich i ptasich z Mongolii, Chin, Azji Środkowej, Francji, USA i Argentyny (pl. 21—39). Autor podaje kryteria klasyfikacji jaj na podstawie skorupy. Wyróżnia kilka poziomów organizacji strukturalnej skorup jaj: teksturę (ultrastrukturalne postaci biomineralizacji), histostrukturę ogólną i ogólną morfologię. Omawia i nazywa typy systemu porów oddechowych i ornamentacji zewnętrznej powierzchni skorupy. Na tej podstawie wyróżnia zasadnicze typy i morfotypy, oparte przede wszystkim na kryteriach ultra- i mikrostrukturalnych, jako najbardziej stabilnych i użytecznych diagnostycznie u grup współczesnych. Parataksonomiczny podział jaj kopalnych obejmuje 14 „rodzin” jaj dinozaurów i 18 grup jaj przypisanych krokodylom, żółwiom i gekkonom. Formalne opisy zawierają obok omówienia swoistych cech budowy skorup zaliczonych do poszczególnych grup także dane o ich występowaniu, spostrzeżenia paleobiologiczne i próbę powiązania parataksonów z grupami naturalnymi organizmów rodzicielskich.
Źródło:
Acta Palaeontologica Polonica; 1991, 36, 2
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Size-shape relationships in the Mesozoic planispiral ammonites
Autorzy:
Parent, H.
Greco, A.F.
Bejas, M.
Powiązania:
https://bibliotekanauki.pl/articles/19942.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
size-shape relationship
Mesozoic
planispiral ammonite
ammonite
Ammonoidea
shell
Cephalopoda
paleontology
marine fossil
Opis:
Ammonites are of outstanding importance in dating events of the Mesozoic and in the study of mechanisms, modes and timing of evolutionary processes. These applications rely on a detailed understanding of their morphology and the modes of variation. It has been known for a long time that their shape is composed of a number of highly correlated features. A new model, called the ADA−model, is introduced for the study of shell morphology (size and shape). The new model is based on classic dimensions which are stable parameters throughout ontogeny, giving very close agreement between pre− dictions and actual observations. It was applied in the exploration of the morphospace occupied by the planispirally coiled and the regularly uncoiled Mesozoic Ammonoidea, based on two new reduced morphospaces introduced for the analysis. Results obtained expose close relationships between size and shape, and general patterns in the ammonite shell morphol− ogy and morphogenesis. (i) The relative apertural height of the whorl section relative to the diameter of the shell (H₂/D) is involved in definition of size and shape. (ii) This same dimension shows a strong tendency to be H₂/D = 0.3. (iii) There are some geometrically possible shell shapes (or morphotypes) which seem to have not been developed since they are not known in the current record. Assuming the known ranges of protoconch size and whorl number as constraints, the ADA−model strongly suggests that these morphotypes have not been developed for the too large or too small sizes the shells would have attained, well outside of the actual size range of the planispirally coiled Ammonoidea. (iv) The law of covariation is shown to be a general pattern within the planispiral ammonites which describes structured variation of the shell shape. (v) A large fraction of the non−structured variation seems originate in the lack of correlation between the rela− tive umbilical diameter and width of the whorl section.
Źródło:
Acta Palaeontologica Polonica; 2010, 55, 1
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Earliest laurasian sauropod eggshells
Autorzy:
Garcia, G
Marivaux, L.
Pelissie, T.
Vianey-Liaud, M.
Powiązania:
https://bibliotekanauki.pl/articles/22561.pdf
Data publikacji:
2006
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
megaloolithid egg shell
Middle Jurassic
Bajocian
Quercy area
France
Sauropoda
fossil egg
paleontology
Opis:
Megaloolithid eggshells, known from many Cretaceous deposits since 19th century, are now recognized as remnants of sauropod dinosaurs. Our paper reports the discovery of megaloolithid egg remains from the Middle Jurassic (Bajocian) of the Quercy area (southwestern France). The new Jurassic ootaxon differs from related Cretaceous oospecies in having unusually thin shells. Even Megaloolithus aureliensis, the thinnest Cretaceous megaloolithid from France is three times thicker than the Jurassic eggshells. The cladistic analysis of ootaxa reveals a peculiar point in contradiction with the phylogenetic results based on skeletal remains: the Megaloolithidae belonged to sauropod dinosaurs, which appear to be the sister group of the hadrosaur eggs (Spheroolithidae oofamilly). This result could indicate a significant amount of homoplasy in the evolution of eggshell structures, depending strongly on the incubation environment (particularly for some characters as ornamentation, pore openings and pore canals), the reproductive physiology and the oviduct function. The Bajocian eggshells might represent the earliest offshoot of the Megaloolithidae oofamily and represent the earliest sauropod eggshell record known from the deposits of Laurasia supercontinent.
Źródło:
Acta Palaeontologica Polonica; 2006, 51, 1
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Bioerosion in shell beds from the Pliocene Roussillon Basin, France: Implications for the (macro)bioerosion ichnofacies model
Autorzy:
de Gibert, J.M.
Domenech, R.
Martinell, J.
Powiązania:
https://bibliotekanauki.pl/articles/23006.pdf
Data publikacji:
2007
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
France
geological setting
Gnathichnus pentax
Pliocene
Radulichnus inopinatus
Roussillon Basin
bioerosion
fossil
ichnofacies
ichnofacies model
ichnology
oyster
shell bed
trace fossil
Opis:
The marine Pliocene at the locality of Nefiach (Roussillon Basin, SE France) includes several shell beds constituted by oysters and scallops that bear a diverse and abundant bioerosion trace fossil assemblage. The most abundant trace fossils are Gnathichnus pentax and Radulichnus inopinatus, produced by the grazing activity of echinoids and polyplacophorans upon algae and other microorganisms coating shell surfaces. Other bioerosion traces include polychaete dwellings (Caulostrepsis taeniola and Maeandropolydora sulcans), sponge boring systems (Entobia isp.), and rare bryozoan borings (Pinaceocladichnus isp.), predation structures (Oichnus simplex and repaired durophagous scars), and foraminiferal fixation pits (Centrichnus cf. eccentricus). The trace fossil assemblage records short−term bioerosion in shellgrounds in a moderate energy setting as evinced by the dominance of epigenic or shallow endogenic structures produced in most cases by “instantaneous” behaviors. The assemblage can be assigned to the Gnathichnus ichnofacies, and it contrasts with that found in Pliocene rocky shores in the same geographic area, which are examples of the Entobia ichnofacies. The Gnathichnusichnofacies is validated as an archetypal one and its recurrency demonstrated since the Jurassic. Entobia and Gnathichnus ichnofacies have to be used in the Mesozoic and Cenozoic as substitutes of the previously existing Trypanites ichnofacies, which is still valid in the Palaeozoic.
Źródło:
Acta Palaeontologica Polonica; 2007, 52, 4
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Shell microstructures in Early Cambrian molluscs
Autorzy:
Kouchinsky, A
Powiązania:
https://bibliotekanauki.pl/articles/23294.pdf
Data publikacji:
2000
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
skeletal fossil
microstructure
shell
biomineralization
mollusc
Early Cambrian
mollusc-like organism
taxonomy
Cambrian
paleontology
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.
Źródło:
Acta Palaeontologica Polonica; 2000, 45, 2
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Upper Cretaceous amniotic eggs from Gobi Desert
Kopalne jaja owodniowców z późnej kredy pustyni Gobi
Autorzy:
Sabath, K.
Powiązania:
https://bibliotekanauki.pl/articles/21370.pdf
Data publikacji:
1991
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
paleontology
Cretaceous
Upper Cretaceous
fossil
amniotic egg
egg shell
Dinosauria
Aves
paleobiology
taphonomy
Gobi Desert
Opis:
There are described several types of Upper Cretaceous fossil amniote eggs, clutches and eggshells, collected during the Polish-Mongolian Paleontological Expeditions (1963—1971) in several localities of the Gobi Desert. Isotopic ratios of C and О are reported and discussed. The eggs may be attributed to saurischian and ornithischian dinosaurs, and palaeognathous birds. Four types of problematica are also described. Taphonomy and restoration of eggshells’ diffusive properties as compared with modern hard-shelled eggs suggest paleoecological interpretation of the nesting conditions as rather dry for smooth-shelled eggs, humid for ornamented eggs, and very humid for the thickest-shelled eggs. Different nest types are postulated for ornamented and smooth eggs, based on taphonomy and shell parameters.
Praca zawiera opis kolekcji późnokredowych jaj ptaków, dinozaurów gadzio- i ptasiomiedniczych, oraz prawdopodobnych skamieniałości miękkoskorupowych jaj innych gadów, odkrytych w latach 1963—71 przez Polsko-Mongolskie Wyprawy Paleontologiczne na pustyni Gobi (fig. 1). Kolekcja ta, gromadząca bogaty materiał kopalny, obejmujący kilkanaście typów jaj późnokredowych, należy do najbogatszych w świecie. Poza przeglądem mikrostruktury skorup (fig. 3, 4, 8) i kształtów jaj (fig. 2, 6; pl. 11—20), przedstawiono szacunkowe wyliczenia objętości, powierzchni, wydłużenia jaj, porowatości skorupy i jej przepuszczalności dla gazów oddechowych, porównując je z równaniami allometrycznymi dla współczesnych jaj ptasich (fig. 7, 9, tab. 1). Zaproponowano funkcjonalne wyjaśnienie roli ornamentacji, kształtu jaj i różnic tafonomicznych między gniazdami jaj ornamentowanych i gładkich (fig. 5) oraz oszacowano warunki i długość trwania inkubacji różnych typów jaj. Wyniki badań składu izotopowego węgla i tlenu w próbkach skorup (fig. 10) wskazują na przewagę lokalnych czynników diagenetycznych w kształtowaniu proporcji trwałych izotopów, nie pozwalając na wiarygodne wnioskowanie o klimacie lub diecie dinozaurów i ptaków kopalnych. Pracę wykonano w Instytucie Paleobiologii PAN w ramach problemu CPBP 04.03.
Źródło:
Acta Palaeontologica Polonica; 1991, 36, 2
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Photography in the ultraviolet and visible violet spectra: Unravelling methods and applications in palaeontology
Autorzy:
Crippa, G.
Masini, S.
Powiązania:
https://bibliotekanauki.pl/articles/31341402.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
paleontology
photography
ultraviolet spectrum
visible violet spectrum
method application
biomineral
fossil species
shell colour
ultraviolet photography
Źródło:
Acta Palaeontologica Polonica; 2022, 67, 3; 685-702
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Piggyback whorls: A new theoretical morphologic model reveals constructional linkages among morphological characters in ammonoids
Autorzy:
Ubukata, T
Tanabe, K.
Shigeta, Y.
Maeda, H.
Mapes, R.H.
Powiązania:
https://bibliotekanauki.pl/articles/20269.pdf
Data publikacji:
2008
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
morphospace
morphology
morphological data
fossil animal
constructional linkage
ammonoid
paleontology
cross-sectional shape
computer simulation
shell growth
morphological diversity
Opis:
A new theoretical morphological model is proposed for the analysis of growth, form and morphospace of ammonoid shells. In this model, the shape of a radial cross section through the shell is simulated by “piggybacking” of successive whorls. The “piggyback whorls model” is defined in terms of the enlarging rate of the perimeter and the proportion of the dorsal wall to the whorl periphery, if an isometric relationship is assumed between perimeter and area of the cross−sectioned whorl. Allometric coefficients on these growth parameters determine how compressed and evolute shells are formed. The present model successfully reproduced some correlations among purely geometric variables that have been reported in previous works and were also observed in our biometric analyses. This model yields a hypothesis of “constructional linkages” between aperture shape and coiling geometry that might provide a functional coupling between hydrostatic and hydrodynamic characters. The model may partly explain Buckman’s Law of Covariation between rib features and shell shapes.
Źródło:
Acta Palaeontologica Polonica; 2008, 53, 1
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-10 z 10

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