Informacja

Drogi użytkowniku, aplikacja do prawidłowego działania wymaga obsługi JavaScript. Proszę włącz obsługę JavaScript w Twojej przeglądarce.

Wyszukujesz frazę "SIBERIA" wg kryterium: Temat


Wyświetlanie 1-15 z 15
Tytuł:
Late Jurassic–Early Cretaceous oysters from Siberia: a systematic review
Autorzy:
KOSENKO, IGOR N.
Powiązania:
https://bibliotekanauki.pl/articles/945953.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
bivalvia
ostreoidea
gryphaeidae
jurassic
cretaceous
siberia
Opis:
The present study reviews the taxonomy of Late Jurassic–Early Cretaceous oysters from the Northern and the Subpolar Urals (Western Siberia) and northern East Siberia. Previous studies have documented 10 species from the genus Liostrea (L. delta, L. cucurbita, L. praeanabarensis, L. anabarensis, L. plastica, L. gibberosa, L. planoconvexa, L. siberica, L. uralensis, L. lyapinensis), and 3 species from the genus Gryphaea (G. borealis and 2 species in open nomenclature). Liostrea gibberosa, L. planoconvexa, L. uralensis, and L. cucurbita are transferred in this study to the genus Pernostrea. Furthermore, two new species of Pernostrea are described: P. mesezhnikovi sp. nov. and P.? robusta sp. nov. Liostrea siberica is transferred to the genus Praeexogyra. Liostrea praeanabarensis and L. anabarensis are attributed to the subgenus Boreiodeltoideum (genus Deltoideum) as well as L. delta sensu Zakharov (1966) which is described here as new species Deltoideum (Boreiodeltoideum) borealis sp. nov. The similar shell morphology of the genera Deltoideum and Pernostrea provides a basis to establish the new tribe Pernostreini trib. nov. in the subfamily Gryphaeinae. Three species are recorded for the first time from Siberia: Nanogyra? cf. thurmanni, “Ostrea” cf. moreana and Gryphaea (Gryphaea) curva.
Źródło:
Acta Palaeontologica Polonica; 2017, 62, 4; 759-778
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Discovery of Middle Jurassic mammals from Siberia
Autorzy:
Averianov, A O
Lopatin, A.V.
Skutschas, P.P.
Martynovich, N.V.
Leshchinskiy, S.V.
Rezvyi, A.S.
Krasnolutskii, S.A.
Fayngertz, A.V.
Powiązania:
https://bibliotekanauki.pl/articles/945775.pdf
Data publikacji:
2005
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
docodonta
morganucodon
dentary
anatomy
bathonian
jurassic
siberia
Opis:
Mammal remains from the Middle Jurassic (Bathonian) Berezovsk Quarry on the south of Krasnoyarsk Territory, West Siberia, Russia are referred to Docodonta indet. (two edentulous fragmentary dentaries) and Mammalia indet. (a single−rooted tooth). The dentaries exemplify a unique combination of plesiomorphic characters found among stem mammals only in Docodonta and Morganucodon: well developed Meckel’s groove, trough for postdentary bones with overhanging medial ridge and a diagonal ridge on the floor separating the “adductor fossa” and angular facet, and well developed and posteroventrally directed pseudangular process with facet for the reflected lamina of angular. Both specimens share with Docodonta the prearticular facet placed ventral to the angular facet and extending posteriorly to the mandibular foramen. This facet is not present in Morganucodon, where the prearticular lies medial to the angular. Medial position of the prearticular in Morganucodon is connected with the compound jaw articulation in this genus, in which a rudimentary articular−quadrate mandibular joint is present medially to the dentary−squamosal joint. In Docodonta indet. from Berezovsk Quarry, Haldanodon and Docodon the position of the prearticular ventral to the angular is connected with the position of the articular complex ventral to the dentary condyle. Such articular complex could not function as a mandibular joint and postdentary bones in Docodonta were used solely for sound transmission. One specimen from Berezovsk Quarry shares with Morganucodon a groove for replacement dental lamina, which was not reported previously for Docodonta. Mammal remains from Berezovsk Quarry are among the oldest occurrences for Docodonta, the first record of Jurassic mammals for Siberia, and only second such record for the whole of Russia.
Źródło:
Acta Palaeontologica Polonica; 2005, 50, 4; 789-797
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The problematic early Cambrian fossil Tumulduria incomperta represents the detached ventral interarea of a paterinid brachiopod
Autorzy:
Skovsted, C.B.
Kouchinsky, A.
Bengtson, S.
Holmer, L.E.
Powiązania:
https://bibliotekanauki.pl/articles/946021.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
brachiopoda
problematica
tommotian stage
terreneuvian
cambrian
siberia
Opis:
The organophosphatic early Cambrian (Terreneuvian, Cambrian Stage 2) fossil Tumulduria incomperta has been problematic ever since its original description in 1969. Comparison of abundant specimens from the Lower Cambrian of Siberia with co-occurring brachiopod valves show that T. incomperta represents the central portion of the ventral interarea of a paterinid brachiopod similar to Cryptotreta neguertchenensis, and that the domed central portion of typical Tumulduria specimens represents the ridge-like pseudodeltidium of the interarea.
Źródło:
Acta Palaeontologica Polonica; 2014, 59, 2; 359-365
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A relict stem salamander: evidence from the Early Cretaceous of Siberia
Autorzy:
Skutschas, P.P.
Powiązania:
https://bibliotekanauki.pl/articles/20727.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
relict
salamander
evidence
evolution
Early Cretaceous
Cretaceous
Siberia
Opis:
The early evolution of salamanders, which are one of the three living groups of lissamphibians, is not well known. Both stem- and crown-group salamanders first appeared in the Middle Jurassic (Bathonian), but subsequently had different evolutionary histories: stem salamanders were thought to have gone extinct in the Late Jurassic, while crown salamanders persist to the present day. Here, I report the discovery of an indeterminate stem salamander in the Lower Cretaceous (Aptian–Albian) Ilek Formation of Western Siberia. This is new evidence that the most basal salamanders survived beyond the Jurassic–Cretaceous boundary and co-existed with crown-group salamanders during approximately the first 40 million years of the known history of salamanders. The recognition of stem salamanders in the Early Cretaceous of Western Siberia adds to the inventory of taxa that suggest this area was a refugium for various groups of vertebrates with Jurassic affinities.
Źródło:
Acta Palaeontologica Polonica; 2016, 61, 1
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Femoral histology and growth patterns of the ceratopsian dinosaur Psittacosaurus sibiricus from the Early Cretaceous of Western Siberia
Autorzy:
Skutschas, P.P.
Morozov, S.S.
Averianov, A.O.
Leshchinskiy, S.V.
Ivantsov, S.V.
Fayngerts, A.V.
Feofanova, O.A.
Vladimirova, O.N.
Slobodin, D.A.
Powiązania:
https://bibliotekanauki.pl/articles/2082328.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Dinosauria
Ceratopsia
Psittacosaurus
bone histology
Cretaceous
Siberia
Russia
Opis:
The early ceratopsian dinosaur Psittacosaurus sibiricus from the Early Cretaceous of Western Siberia, Russia, is one of the most advanced and largest (up to 2.5 m) members of the genus. Here we present a description of ontogenetic changes in the long-bone histology of this species. Analysis of a growth series of femora demonstrates significant histological maturation during ontogeny, expressed by the progressive appearance of signs of bone remodeling (erosion bays, secondary bone formation), decreasing of vascularity, changing of the orientation of vascular canals from reticular to longitudinal, and appearance of parallel-fibred bone in the outer part cortex. These ontogenetic changes in the longbone histology of P. sibiricus are generally similar to those of another relatively advanced species, P. lujiatunensis from China. The basal P. mongoliensis from Mongolia shows less mature long-bone histology during late ontogeny (e.g., the late appearance of signs of remodeling and the predominance of reticular vascularization at later stages). We suggest that the earlier achievement of histological maturity is an evolutionary trend of the genus Psittacosaurus.
Źródło:
Acta Palaeontologica Polonica; 2021, 66, 2; 437-447
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The new stem-group brachiopod Oymurania from the lower Cambrian of Siberia
Autorzy:
Kouchinsky, A.
Holmer, L.E.
Steiner, M.
Ushatinskaya, G.T.
Powiązania:
https://bibliotekanauki.pl/articles/21826.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Brachiopoda
brachiopod
Oymurania
Mickwitzia
Micrina
Setatella
Lower Cambrian
Cambrian
Siberia
Opis:
A stem-group brachiopod, Oymurania gravestocki Ushatinskaya gen. et sp. nov. is described herein from the middle Atdabanian-lower Botoman Stages (-Cambrian Stage 3) of the Siberian Platform. The fossils were extracted from limestone beds of the Emyaksin, Perekhod, and Pestrotsvet formations as assemblages of disarticulated orthoconic to cyrtoconic porous shells in apatite preservation. The originally organophosphatic shells of Oymurania are externally similar to mitral sclerites (ventral valves) of the stem-group brachiopod Micrina, although no sellate-like sclerites, nor differentiated subapical area with apophyses were recognised in our material. The range of Oymurania shells with sub-central to posteromarginal apex is similar to that of ventral valves ofMickwitzia. Oymurania is also characterised by the system of radial and orthogonal canals open in pairs or triplets in small depressions or indentations of growth lamellae in the outer shell surface. The orthogonal (Micrina-Setatella type) and radial (horizontal setigerous tubes) canals are widespread among the early Cambrian stem-group brachiopods, such as Micrina, Mickwitzia, and Setatella. In addition to these canals, Oymurania exhibits a well-developed acrotretoid columnar microstructure, also known from Setatella. A broad subapical platform in cyrtoconic shells (presumably ventral valves) of Oymurania is interpreted homologous to the deltoid area in mitrals of Micrina and pseudointerarea/interarea in ventral valves of Setatella/paterinid brachiopods. Except with probable cell imprints and openings of orthogonal canals, no morphological differentiation was, however, reflected by the shell interior of Oymurania gravestocki. Being closely related to tannuolinids and mickwitziids, Oymurania complements the picture of diversification of the early Cambrian stem-group brachiopods that occurred in parallel with radiation of paterinids and other crow-group brachiopods on the Siberian Platform and worldwide.
Źródło:
Acta Palaeontologica Polonica; 2015, 60, 4
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Jurassic floras with Siberian affinities in south-western Mongolia
Autorzy:
Sodov, Z
Powiązania:
https://bibliotekanauki.pl/articles/23488.pdf
Data publikacji:
1993
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Anomozamites
floral remnant
Mongolia
Siberia
flora
fossil plant
Coniopteris
Jurassic
paleontology
Źródło:
Acta Palaeontologica Polonica; 1993, 38, 1-2
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Lower Turonian record of belemnite Praeactinocamax from NW Siberia and its palaeogeographic significance
Autorzy:
Kostak, M.
Wiese, F.
Powiązania:
https://bibliotekanauki.pl/articles/21284.pdf
Data publikacji:
2008
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Lower Turonian
belemnite
Praeactinocamax
Siberia
paleogeography
Belemnitellidae
Turonian
Upper Cretaceous
Russia
Opis:
Specimens of the belemnitellid Praeactinocamax Naidin, 1964 are described from the Upper Cretaceous of NW Siberia (Taimyr Region, Lower Agapa River, Russia). The rostra determined as Praeactinocamax aff. plenus consist of an aragonitic anterior part and a calcitic posterior part with a sharp boundary in between. This boundary surface is referred to as the “alveolar fracture”, and it is a typical morphological feature of early belemnitellids and not a result of diagenetic processes. The occurrence of Praeactinocamax in Arctic areas shows a wider palaeobiogeographical distribution of the genus in the Late Cenomanian–Early Turonian interval than previously known. This finding suggests that migration of the late Cenomanian–early Turonian fauna occurred across Turgai channel. The geographic position of these new records may also explain the occurrence of Praeactinocamax in the Turonian of the US Western Interior Seaway, the origin of which has been hitherto unclear.
Źródło:
Acta Palaeontologica Polonica; 2008, 53, 4
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The ammonoid recovery after the end-Permian mass extinction: Evidence from the Iran-Transcaucasia area, Siberia, Primorye, and Kazakhstan
Autorzy:
Zakharov, Y.D.
Abnavi, N.M.
Powiązania:
https://bibliotekanauki.pl/articles/21520.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
ammonoid
Ammonoidea
recovery
Permian
Triassic
extinction
evidence
Iran
Siberia
Russia
Kazakhstan
Opis:
Investigations of the Upper Permian strata in the Iran−Transcaucasia resulted in identification of 32 ammonoid genera. The majority of ammonoids in this collection belong to the order Ceratitida (75%). Among Dzhulfian ceratitid ammonoids representatives of the family Araxoceratidae (Otoceratoidea) are most abundant. The assemblage structure changed radically during latest Permian (Dorashamian) time, bringing a domination of the family Dzhulfitidae. The Induan (Lower Triassic) succession in the Verkhoyansk area provided a few groups of ammonoids which are Palaeozoic in type: families Episageceratidae (Episageceras), Xenodiscidae (Aldanoceras and Metophiceras), and Dzhulfitidae (Tompophiceras) and superfamily Otoceratoidea (Otoceras and Vavilovites). It demonstrates the survival of ammonoids belonging to these groups the Permian–Triassic (P–T) boundary extinction event and their quick migration to the vast ar− eas of higher latitudes (together with some representatives of the Mesozoic−type families). Induan–Olenekian ammonoid successions in South Primorye, Mangyshlak, and Arctic Siberia illustrate the high rate of Early Triassic ammonoid recov− ery in both the Tethys and the Boreal realm. New ammonoid taxa are described: Proptychitina subordo nov., Ussuritina subordo nov., Subbalhaeceras shigetai gen. and sp. nov. (Flemingitidae), Mesohedenstroemia olgae sp. nov. (Heden− strormiidae), and Inyoites sedini sp. nov. (Inyoitidae).
Źródło:
Acta Palaeontologica Polonica; 2013, 58, 1
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
Tytuł:
A sauropod foot from the Early Cretaceous of Western Siberia, Russia
Autorzy:
Averianov, A O
Voronkevich, A.V.
Maschenko, E.N.
Leshchinskiy, S.V.
Fayngertz, A.V.
Powiązania:
https://bibliotekanauki.pl/articles/20801.pdf
Data publikacji:
2002
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Ilek Formation
Titanosauriformes
Cretaceous
Russia
Siberia
Sauropoda
sauropod foot
paleontology
postcranial skeleton
Opis:
We describe a reasonably complete sauropod foot from the Early Cretaceous (Aptian–Albian) Ilek Formation at the Shestakovo locality in Western Siberia, Russia.It shows some primitive characters, such as slender metatarsals, a relatively long second pedal ungual, and three claws.In the likely presence of the laterodistal process on the first metatarsal the Shestakovo sauropod is similar with diplodocoids, but its more elongated and gracile first metatarsal resembles brachiosaurids (Brachiosaurus, Pleurocoelus, and Cedarosaurus), titanosaurids (Laplatasaurus), and Euhelopus. Pleurocoelus−like isolated teeth from the Shestakovo assemblage may support the brachiosaurid affinities of the Shestakovo sauropod, but a strongly procoelous mid−caudal vertebra from another locality in the same formation establishes the presence of a titanosaurid in the fauna.The foot described is referred here to as Titanosauriformes gen.et sp.indet.
Źródło:
Acta Palaeontologica Polonica; 2002, 47, 1
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The tube wall of Cambrian anabaritids
Autorzy:
Kouchinsky, A
Bengtson, S.
Powiązania:
https://bibliotekanauki.pl/articles/22467.pdf
Data publikacji:
2002
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Anabaritida
biomineralization
recrystallization
skeleton
tube wall
wall structure
aragonite
celestite
barite
Siberia
anabaritid
Cambrian
paleozoology
Opis:
Celestite/barite−replaced and phosphate−replicated tubes of Early Cambrian anabaritids from the northern part of the Siberian Platform (Anabar Shield) give new evidence on the wall−structure of these enigmatic fossils. The walls consist of fibres, interpreted as reflecting an original aragonitic fabric. Bundles of fibres are arranged in growth lamellae, and the latter form an angle of at least 45° with the inner tube wall. Where the outer tube surface projects into annular flanges, the lamellae have a chevron−like section due to the backwards deflection of the outer parts. Anabaritids are usually referred to the Cnidaria or left without systematic assignment, but earlier suggestions included affinity to the serpulid polychaetes. The chevron structure resembles that previously exclusively known from serpulids, but the presence of internal tooth−like structures in anabaritid tubes, perhaps compromising up−and−down movement through the tubes, continue to make a direct assignment to the Serpulida questionable.
Źródło:
Acta Palaeontologica Polonica; 2002, 47, 3
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A new genus of Late Ordovician-Early Silurian pentameride brachiopods and its phylogenetic relationships
Autorzy:
Jin, J
Popov, L.E.
Powiązania:
https://bibliotekanauki.pl/articles/22557.pdf
Data publikacji:
2008
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
pentameride brachiopod
brachiopod
paleontology
new genus
Siberia
Late Ordovician
Canada
Brachiopoda
Early Silurian
Protanastrophia repanda
Parastrophinidae
Opis:
Protanastrophia repanda gen. et sp. nov. is a reef−dwelling parastrophinid brachiopod in the Lower Silurian (uppermost Telychian) Attawapiskat Formation of the Hudson Bay region of Canada. It is characterized by a small, quasi−smooth shell with gentle anterior costae, a tendency towards an asymmetrical, sigmoidal anterior commissure, and widely separate, subparallel inner hinge plates. Protanastrophia first appeared in the marginal seas of Siberia (Altai, Mongolia) during the Late Ordovician, retaining the primitive character of discrete inner hinge plates in the superfamily Camerelloidea, and preferred a carbonate mound depositional environment. It survived the Late Ordovician mass extinction and subsequently spread to Baltica and Laurentia during Early Silurian (Llandovery) time. Superficially similar asymmetrical shells of Parastrophina portentosa occur in the Upper Ordovician carbonate mound facies of Kazakhstan but differ internally from the new genus in having a septum−supported septalium. Phylogenetic analysis indicates that, within the Camerelloidea, asymmetrical shells with a sigmoidal anterior commissure evolved in Protanastrophia repanda and Parastrophina portentosa independently during the Late Ordovician as a case of homoplasy. The two species belong to separate parastrophinid lineages that evolved in widely separate palaeogeographic regions.
Źródło:
Acta Palaeontologica Polonica; 2008, 53, 2
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Aragonitic rostra of the Turonian belemnitid Goniacamax: arguments from diagenesis
Autorzy:
Dauphin, Y
Williams, C.T.
Barskov, I.S.
Powiązania:
https://bibliotekanauki.pl/articles/20211.pdf
Data publikacji:
2007
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Turonian
sea shell
Cephalopoda
belemnite
calcite
Goniocamax
rostrum
skeleton
sea cephalopod
diagenesis
paleoenvironment
freshwater shell
Belemnitida
aragonite
Siberia
belemnitid rostrum
Piasina River
paleontology
Opis:
The hypothesis that belemnitid rostra are formed by primary biogenic low−Mg calcite is widespread. However, the coexistence in the same rostrum of both aragonitic and calcitic components has been reported in true belemnites (Goniocamax, Turonian). A combined microstructural and chemical composition study of the comparison of shells with undisputed mineralogy from the same site as the Turonian Goniocamax, shows that these aragonitic shells display the effects of diagenetic alteration. These observations favour the hypothesis that belemnite rostra are composed of primary aragonite, rather than low−Mg calcite, and are consistent with all other cephalopod shells. Calcitic and aragonitic rostra are also known in other Dibranchiata such as Triassic Aulacocerida and Eocene Belopterina. Diagenetic changes such as shown here may clearly affect palaeo−environmental interpretations based on carbonate shells.
Źródło:
Acta Palaeontologica Polonica; 2007, 52, 1
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Late Eocene scyliorhinid sharks from the Trans-Urals, Russia
Autorzy:
Malyshkina, T.
Powiązania:
https://bibliotekanauki.pl/articles/22075.pdf
Data publikacji:
2006
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Carcharhiniformes
Elasmobranchii
Eocene
Foumtizia pattersoni
Foumtizia zhelezkoi
geological setting
Late Eocene
Premontreia
Premontreia uralica
Scyliorhinidae
Siberia
fossil shark
locality
paleontology
remains
scyliorhinid shark
shark
tooth
systematics
Opis:
Priabonian deposits from two localities, Kurgan and Derney, in the Trans−Urals (Western Siberia) have yielded numerous selachian teeth. The carcharhiniform family Scyliorhinidae is represented by three species, including two new: Premontreia uralica sp. nov., Foumtizia zhelezkoi sp. nov., and F. pattersoni (Cappetta, 1976). Both genera are recorded from the West−Siberian Basin for the first time. Presumably all three species (including the one morphologically mimicking F. pattersoni, a species recorded from Ypresian of England) are endemic for the Trans−Urals region (contrary to the cosmopolitan lamniforms recorded previously from the area. The known distribution pattern of extant scyliorhinids supports the probability of endemism of the cat sharks from the West−Siberian Basin, which has also been isolated geographically from the Peri−Tethys during the Late Eocene marine regression. The peculiar local environmental conditions due to the Priabonian climatic cooling in the Boreal realm might have also facilitated the speciation.
Źródło:
Acta Palaeontologica Polonica; 2006, 51, 3
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-15 z 15

    Ta witryna wykorzystuje pliki cookies do przechowywania informacji na Twoim komputerze. Pliki cookies stosujemy w celu świadczenia usług na najwyższym poziomie, w tym w sposób dostosowany do indywidualnych potrzeb. Korzystanie z witryny bez zmiany ustawień dotyczących cookies oznacza, że będą one zamieszczane w Twoim komputerze. W każdym momencie możesz dokonać zmiany ustawień dotyczących cookies