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    Wyświetlanie 1-13 z 13
    Tytuł:
    Palaeomagnetism of Permian through Early Triassic sequences in central Spitsbergen: contribution to magnetostratigraphy
    Autorzy:
    Nawrocki, J.
    Grabowski, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/2059421.pdf
    Data publikacji:
    2000
    Wydawca:
    Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
    Tematy:
    Spitsbergen
    Permian-Early
    Triassic
    magnetostratigraphy
    correlation
    Opis:
    A total of 297 samples for palaeomagnetic studies were collected from Upper Gzhelian through Spathian sediments of the Isfjorden area (central Spitsbergen). In spite of extensive Cenozoic remagnetisation the studied rocks yielded palaeomagnetic poles and magnetostratigraphy. Almost all Permian samples were reversely magnetised during Kiaman superchron. Normal-polarity samples appear in the Ufimian and Kazanian sediments. The topmost samples from the Kapp Starostin Formation (Upper Permian) contain reverse polarity. The magnetic polarity record noted in the Early Triassic (Griesbachian-Spathian) sequences is fully convergent with magnetic polarity schemes obtained in the Canadian Arctic and Deltadalen type section.
    Źródło:
    Geological Quarterly; 2000, 44, 2; 109-117
    1641-7291
    Pojawia się w:
    Geological Quarterly
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Middle Carboniferous to Early Permian bryozoans from Spitsbergen
    Autorzy:
    Nakrem, H A
    Powiązania:
    https://bibliotekanauki.pl/articles/19930.pdf
    Data publikacji:
    1994
    Wydawca:
    Polska Akademia Nauk. Instytut Paleobiologii PAN
    Tematy:
    fauna kopalna
    fauna borealna
    perm
    Spitsbergen
    skamienialosci
    karbon
    paleontologia
    mszywioly
    Bryozoa
    Opis:
    Bryozoans from the Nordenskiöldbreen Formation (Middle Carboniferous Moscovian through Early Permian Sakmarian) and the Gipshuken Formation (late Sakmarian - late Artinskian), from central Spitsbergen, Svalbard, are represented by 36 species (22 genera). One species is new: Hinaclema svalbardensis of the order Trepostomata. The bryozoan fauna is typical Boreal and resembles those from the Timan-Pechora region (western Siberia) and the Urals. Similarity indices based on generic composition show that the Boreal fauna became more endemic by the late Early Permian, clearly separated from the Tethyan faunas. Several species have stratigraphic ranges in Spitsbergen longer than elsewhere.
    Artykuł zawiera taksonomiczną rewizję mszywiołów z formacji Nordenskiöldbreen (środkowy karbon-wczesny perm) i Gipshuken (perm) Spitsbergenu, obejmując rownież gatunki będące niegdyś przedmiotem publikacji Czarnieckiego (1964) i Małeckiego (1977). W sumie zidentyfikowano 36 gatunków z 22 rodzajów; tylko jeden gatunek nowy. Fauna mszywiołów jest typowo borealna i przypomina fauny obszaru timańsko-peczorskiego i Uralu. Od końca wczesnego permu fauny borealne stały się bardnej endemiczne, wyraźnie odrębne od tetydzkich. Wiele gatunków mszywiołów miało dłużzsze zasięgi w permie Spitsbergenu niż gdzie indziej.
    Bryozoer fra Nordenskiöldbreenformasjonen (midtre karbon moskva til tidlig perm sakmar) og Gipshukenformasjonen (sen sakmar - sen artinsk) fra Spitsbergen, Svalbard, er representert med 36 arter (22 slekter). En art er ny: Hinaclema svalbardensis, orden Trepostomata. Bryozofaunaen er typisk boreal (nordlig) og ligner på tilsvarende fauna beskrevet fra Timan-Pechoraområdet (vestlige Sibir) og fra Uraldistriktet. Likhetsindekser basert på slektssammensetningen viser at den Boreale faunaen ble stadig mer endemisk mot slutten av tidlig perm, og er markant forskjellig fra Tethysfaunaen i sør. Mange arter har en stratigrafisk utbredelse på Spitsbergen som avviker fra utbredelsen i andre områder.
    Źródło:
    Acta Palaeontologica Polonica; 1994, 39, 1; 45-116
    0567-7920
    Pojawia się w:
    Acta Palaeontologica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Callipterid pteridosperms from the Early Permian of Ukraine
    Autorzy:
    Boyarina, N
    Powiązania:
    https://bibliotekanauki.pl/articles/21331.pdf
    Data publikacji:
    1994
    Wydawca:
    Polska Akademia Nauk. Instytut Paleobiologii PAN
    Tematy:
    paprocie nasienne
    perm
    skamienialosci
    paleobotanika
    Raminervia
    paleontologia
    Raminervia mariopteroides
    Ukraina
    Opis:
    In terrigenous rocks of the early Permian age, below the limestone P6, of the Western Donets Basin two new pteridosperm species have been identified. One of them had phyllosperms with seed scars situated near the base and in the middle part of a pinnule, at the ends of vein-like off-shoots. Its foliage consists of dichotomously branched pinnate to tripinnate fronds, sphenopteroid pinnules and intercalary pinnae and pinnules. The foliage is very variable. Immature, semi-mature, and mature pinnae and pinnules are known. These plants grew probably along the margins of floodplain lakes. The name Raminervia mariopteroides gen. et sp. n. is proposed here for them. The second species, Dichophyllum cuneata sp. n., is characterized by pinnate to bipinnate fronds with a dichotomy of the primary rachis, broadly wedge-shaped pinnules and similarly shaped intercalary pinnules. Plants of the species probably grew on elevated lots of the floodplain and on the alluvial-lacustrine plain.
    Praca zawiera opis dwu nowych gatunków permskich paproci nasiennych o liściach typu „Callipteris” (nazwa ta jest młodszym synonimem rodzaju dzisiejszych paproci i w paleobotanice paleozoiku nie może być używana). Jeden z tych gatunków stanowi podstawę do wydzielenia nowego naturalnego rodzaju Raminervia.
    Вивченi рештки викопних рослин виявленi в ранньопермських вiдкладах Захiдного Донбасу. Викопний матерiал зiбpaн в аргілiтових та алевролiтових вiдкладах озерного i алювiально-озерного генезису в iнтервалi poзpiзy мiж вапняками Р⁰₅ та Р₆. Описано один природний рiд Raminervia gen. n. та два види - Raminervia mariopteroides sp. n. i Dichophyllum cuneata sp. n. Рiд Raminervia характеризуеться фiдоспермами, якi при основi та в середнiй частинi несуть насiннi рубцi. До кожного рубця пiдходить вiдгалуження жилки. Листи Raminervia mariopteroides дихотомічно-перистi тричi псристо-складнi, з дихотоміϵю головної oci, сфеноптеридними лопатевими пiр’ячками та промiжними елементами останного та передостаннього порядку. Пiр’я i пiр’ячки мор-фолопчно рiзноманiтнi, що обумовлено рiзними стадiями росту листа. Листи Dichopyllum cuneata дiхотомiчно-перистi двічi перисто-складнi, з дихотомiею головної oci, широко клиновидними пір’ячками, розciченними на сегменти майже до основи, та з проміжними елементами останнього порядку. Виходячи iз морфологiчних i тафономiчних ознак рослинних решток та з генезису порід, рослини виду R. mariopteroides росли по берегам заплавних озер, утворюючи озерно-заплавні фiтоценози, а представники виду D. cuneata буди розповсюджені на пiдвищених дiлянках заплави та алювiально-озерної рiвнини.
    Źródło:
    Acta Palaeontologica Polonica; 1994, 39, 1; 117-133
    0567-7920
    Pojawia się w:
    Acta Palaeontologica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    On the affinities of Tetraceratops insignis, an Early Permian synapsid
    Autorzy:
    Amson, E.
    Laurin, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/20520.pdf
    Data publikacji:
    2011
    Wydawca:
    Polska Akademia Nauk. Instytut Paleobiologii PAN
    Tematy:
    Tetraceratops insignis
    Early Permian
    Permian
    synapsid
    Therapsida
    phylogenesis
    biogeography
    range extension
    Paleozoic
    Pangaea
    North America
    fossil
    paleontology
    Opis:
    The affinities of the Early Permian synapsid Tetraceratops insignis have been reevaluated several times since the early 20th century, being considered as an eothyridid, a sphenacodontid, or a therapsid. This controversy continues into the 21st century, with recently raised doubts about the interpretation of Tetraceratops as the oldest known therapsid, a hypothesis supported by the only redescription of this fossil in the second half of the 20th century. Our study examines the arguments proposed to refute therapsid affinities, and concludes that Tetraceratops indeed is the sister−group of all other known therapsids. The most recently published phylogenetic data matrix that includes Tetraceratops fails to confirm its therapsid affinities. However, adding seven characters to that matrix leads to the conclusion that Tetraceratops is the basal−most and oldest therapsid. The recent suggestion of a Laurasian origin of therapsids appears poorly supported; too few data are available on the distribution of Permian synapsids to settle this question.
    Źródło:
    Acta Palaeontologica Polonica; 2011, 56, 2
    0567-7920
    Pojawia się w:
    Acta Palaeontologica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Tooth microstructure of the Early Permian aquatic predator Stereosternum tumidum
    Autorzy:
    Pretto, F.A.
    Cabreira, S.F.
    Schultz, C.L.
    Powiązania:
    https://bibliotekanauki.pl/articles/21575.pdf
    Data publikacji:
    2014
    Wydawca:
    Polska Akademia Nauk. Instytut Paleobiologii PAN
    Opis:
    A histological investigation of the feeding apparatus of a Stereosternum specimen revealed a great number of adaptations in the structure and insertion of teeth, to deal with breakage risks. The tooth wall is composed of different layers of dentine, varying in orientation and composition. This mixed arrangement may have increased tooth resistance to lateral tension. The tooth insertion also involves more than one mechanism. The teeth are located inside shallow tooth sockets and are held in place by a tripartite periodontium (composed of alveolar bone, cementum and possibly soft periodontal tissue) and accessory structures, here termed anchorage trabeculae (mainly composed of cementum). Fully grown teeth are ankylosed to the bottom of the tooth socket. The recognition of alveolar bone and cementum (and the possible presence of a soft periodontal ligament) reinforces the idea that these tissues were widespread among Amniota, not being exclusive to mammals and archosaurs. The adaptations identified here reinforce the hypothesis that Stereosternum was an active aquatic predator.
    Źródło:
    Acta Palaeontologica Polonica; 2014, 59, 1
    0567-7920
    Pojawia się w:
    Acta Palaeontologica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Early Permian solitary rugose corals from Kruseryggen (Treskelodden Fm., Hornsund area, southern Spitsbergen)
    Autorzy:
    Chwieduk, Edward
    Powiązania:
    https://bibliotekanauki.pl/articles/94285.pdf
    Data publikacji:
    2009
    Wydawca:
    Uniwersytet im. Adama Mickiewicza w Poznaniu
    Tematy:
    Rugosa
    Early Permian
    Treskelodden Formation
    Spitsbergen
    wczesny perm
    formacja Treskelodden
    Opis:
    A collection of solitary rugose corals collected from the Treskelodden Formation of the Kruseryggen Hill, Hornsund area, south Spitsbergen, consists of 30 specimens representing the Bothrophyllidae family with the genera Bothrophyllum, Caninophyllum, Hornsundia, and Timania (5 species), and an indeterminate family with the genus Svalbardphyllum (one species). These large, dissepimental forms, dating from the Early Sakmarian (Tastubian), indicate a warm-water environment. The lithology, the thickness of the succession, the reddish hue and the abrasion of the fossils indicate that the area of the inner Hornsund showed a relief that enabled considerable erosion of the elevated areas and redeposition of the fossils at remote locations. The changing morphology of this area during the Early Permian was probably influenced by synsedimentary block tectonics.
    Źródło:
    Geologos; 2009, 15, 1; 57-75
    1426-8981
    2080-6574
    Pojawia się w:
    Geologos
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A new euselachian shark from the early Permian of the Middle Urals, Russia
    Autorzy:
    IVANOV, ALEXANDER O.
    DUFFIN, CHRISTOPHER J.
    NAUGOLNYKH, SERGE V.
    Powiązania:
    https://bibliotekanauki.pl/articles/945229.pdf
    Data publikacji:
    2017
    Wydawca:
    Polska Akademia Nauk. Instytut Paleobiologii PAN
    Tematy:
    chondrichthyes
    elasmobranchii
    teeth
    permian
    russia
    urals
    Opis:
    The isolated teeth of a new euselachian shark Artiodus prominens Ivanov and Duffin gen. et sp. nov. have been found in the Artinskian Stage (Early Permian) of Krasnoufimskie Klyuchiki quarry (Sverdlovsk Region, Middle Urals, Russia). The teeth of Artiodus possess a multicuspid orthodont crown with from four to nine triangular cusps; prominent labial projection terminating in a large round tubercle; distinct ornamentation from straight or recurved cristae; oval or semilunar, elongate, considerably vascularized base; dense vascular network formed of transverse horizontal, ascending, short secondary and semicircular canals. The teeth of the new taxon otherwise most closely resemble the teeth of some protacrodontid and sphenacanthid euselachians possessing a protacrodont-type crown, but differ from the teeth of all other known euselachians in the unique structure of the labial projection. The studied teeth vary in crown and base morphology, and three tooth morphotypes can be distinguished in the collection reflecting a moderate degree of linear gradient monognathic heterodonty. The range of morphologies otherwise displayed by the collection of teeth shows the greatest similarity to that described for the dentitions of relatively high-crowned hybodontids from the Mesozoic. The internal structure of the teeth, including their vascularization system is reconstructed using microtomography. The highest chondrichthyan taxonomic diversity is found in the Artinskian, especially from the localities of the Middle and South Urals.
    Źródło:
    Acta Palaeontologica Polonica; 2017, 62, 2; 290-298
    0567-7920
    Pojawia się w:
    Acta Palaeontologica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Stephanian-Early Permian basaltic trachyandesites from the Sławków and Nieporaz-Brodła Grabens near Kraków, Southern Poland
    Autorzy:
    Lewandowska, A.
    Rospondek, M. J.
    Nawrocki, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/191897.pdf
    Data publikacji:
    2010
    Wydawca:
    Polskie Towarzystwo Geologiczne
    Tematy:
    Upper Carboniferous/Permian volcanism
    a-a lava flows
    autoclastic breccias
    basaltic trachyande-sites
    transitional calc-alkaline to alkaline rocks
    hydrous magma
    Opis:
    In the Kraków-Lubliniec section of the major Hamburg-Kraków-Dobrogea Fault Zone (HKDFZ), the Stephanian-Early Permian magmatic activity was simultaneous with subsidence/uplift of formed blocks. In the proximity of the uplifted areas the sedimentation started with fanglomerates, distally passing into playa siltstone and was accompanied by volcanism. In the Nieporaz-Brodła graben, basaltic trachyandesite a-a lava flows with autoclastic breccias reach ca. 150 m in thickness. The weathering recorded as adhesive rims around breccia clasts reflects palaeosoil formation during quiescence periods between the eruptions. The eruptions were effusive although scoriaceous lava indicates high volatile content of the magma. The water content before eruption had to be over 2 wt. percent. Only then the crystallisation model predicts accurately the type, composition and order of the crystallising phases. Thus, the basaltic trachyandesite magma originated from a source containing hydrous phase (i.e., amphibole or phlogopite). All the studied basaltic trachyandesites had fayalitic olivine on their liquidus reflecting the crystallisation stage in a magma chamber at crustal depths. During final decompression on the magma ascent due to water exsolution, the olivine was followed by plagioclase, spinel, augite, ilmenite, apatite, K-feldspar and residual high-K rhyolitic glass. The high potassium content of these volcanics was thus a primary feature reflecting the source geochemistry and differentiation trend, and its consequence was potassium metaso- matism. Due to water exsolution the glass was altered, however, homogenous interstitial glass survived in some rocks. The glass is strongly enriched in incompatible trace elements, showing that it is a highly fractionated residual melt fraction of the basaltic trachyandesite magma. Thus, the glass geochemistry reflects the trend of fractional crystallisation indicating that co-occurring K-rich felsic rocks were not derived from the same magma. All the basaltic trachyandesites studied have calc-alkaline to alkaline affinity. They contain fayalitic olivine and are low in MgO <5 wt. %, Cr and Ni, the features characteristic for evolved magmas. They show significant negative Sr/Sr*> 0.5-0.80 and small Eu/Eu* > 0.9-1.0 anomalies suggesting fractionation of plagioclase. The Eu/Eu* anomaly is probably compensated by amphibole retaining in the source. Negative Nb, Ti anomalies suggest Fe-Ti oxide fractionation characteristic for calc-alkaline evolution trend. A significant enrichment in LREE relatively to HREE (La/Yb > 10) indicates subduction-related metasomatism. However, the described tectonic context is inconsistent with subduction related characteristics. Concluding, the observed geochemical characteristics indicate remarkable role of water in magma evolution. The volcanism was related to strike-slip dextral movement along the Kraków-Lubliniec section of HKDFZ, transformed into crustal extension and subsidence, the features typical for the formation of pull-apart basins, in the late stages of the Variscan orogen evolution.
    Źródło:
    Annales Societatis Geologorum Poloniae; 2010, 80, No 3; 227-251
    0208-9068
    Pojawia się w:
    Annales Societatis Geologorum Poloniae
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Orthacanthus platypternus (Cope, 1883) (Chondrichthyes: Xenacanthiformes) teeth and other isolated vertebrate remains from a single horizon in the early Permian (Artinskian) Craddock Bonebed, lower Clear Fork Group, Baylor County, Texas, USA
    Autorzy:
    Johnson, G. D.
    Powiązania:
    https://bibliotekanauki.pl/articles/138953.pdf
    Data publikacji:
    2018
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    Orthacanthus platypternus
    early Permian
    Craddock Bonebed
    Texas
    ryby chrzęstnoszkieletowe
    ryby chrzęstne
    chrzęstniki
    Chondrichthyes
    wczesny perm
    Teksas
    Opis:
    An unusual 6–8 cm layer of prismatic cartilage and matrix containing some 8,800 teeth, coprolites, incomplete occipital spines, and denticles of Orthacanthus platypternus (Cope, 1883) occurs in the lower Permian (Artinskian) Craddock Bonebed in Texas, USA. It is the only species of shark present in the Clear Fork Group except for three worn Xenacanthus Beyrich, 1848 occipital spine fragments and two teeth of ?Lissodus (Polyacrodus) zideki (Johnson, 1981) (Hybodontoidei), both being the first occurrences in this unit. Analysis of measurements of teeth with complete bases randomly selected from 3,050 initially available teeth failed to reveal the presence of sexual dimorphism or the discrete presence of juveniles as expected, based on an independent study which identified the presence of Orthacanthus juvenile occipital spines. A few highly symmetrical small teeth are present, which had not been previously observed in the Texas lower Permian. They may be symphyseals and restricted only to juveniles. Other unusual teeth include germinal teeth and deformed teeth, both of which occur in the Clear Fork and underlying Wichita groups. One tooth displays an apparent example of the equivalent of an “enamel pearl” on one of its cusps. The most unusual teeth are those that appear to have undergone various stages of resorption. Only the lingual margin of the base is affected in which the apical button is resorbed to varying degrees until only the labial margin with the basal tubercle and the three cusps are all that remain. If the teeth were undergoing resorption, then the perplexing problem is why the apical button is resorbed and not the superjacent basal tubercle. Other vertebrate remains include palaeoniscoid scales and teeth and unidentified tetrapod bone fragments, jaw fragments, and teeth. Rare fragments of bones (scales?) bear a “comb edge” which have not been previously observed in the Texas lower Permian.
    Źródło:
    Acta Geologica Polonica; 2018, 68, 3; 421-436
    0001-5709
    Pojawia się w:
    Acta Geologica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Early diagenetic siderite in the Panorama Point Beds (Radok Conglomerate, Early to Middle Permian), Prince Charles Mountains, East Antarctica
    Autorzy:
    Krajewski, Krzysztof P.
    Gonzhurov, Nikolai A.
    Laiba, Anatoly A.
    Tatur, Andrzej
    Powiązania:
    https://bibliotekanauki.pl/articles/2051608.pdf
    Data publikacji:
    2010
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    Antarctica
    Prince Charles Mts
    Radok Conglomerate
    Permian
    siderite
    fresh−water environment
    Źródło:
    Polish Polar Research; 2010, 2; 169-194
    0138-0338
    2081-8262
    Pojawia się w:
    Polish Polar Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A new Early Triassic gastropod genus and the recovery of gastropods from the Permian-Triassic extinction
    Autorzy:
    Nutzel, A
    Powiązania:
    https://bibliotekanauki.pl/articles/22642.pdf
    Data publikacji:
    2005
    Wydawca:
    Polska Akademia Nauk. Instytut Paleobiologii PAN
    Tematy:
    gastropod
    Werfenella
    Alps Mountains
    Purpurinidae
    Werfen Formation
    Olenekian
    new genus
    mass extinction
    Early Triassic
    Triassic
    Gastropoda
    Permian
    Turbo rectecostatus
    paleontology
    Opis:
    The common Early Triassic (Olenekian) gastropod Turbo rectecostatus from the upper Werfen Formation of the Alps is placed in the new genus Werfenella. Elimination of the wrong or outdated generic assignments of Late Palaeozoic and Early Mesozoic gastropods to archetypical genera such as Turbo, Trochus, or Natica (all with Recent type species) represents an important step toward understanding the evolutionary history of the gastropods across the Permian/Triassic mass−extinction event. The first appearance of Werfenella in the Olenekian, as well as the origination of other groups of gastropods, suggests an early turnover in the aftermath of the end−Permian mass extinction event. The relatively large size of Werfenella (up to 35 mm) sheds doubt on assertions that all Early Triassic gastropods are microgastropods (Lilliput effect). The new genus is placed in the caenogastropod family Purpurinidae and represents its earliest occurrence. However, a placement of Werfenella in the Archaeogastropoda (Vetigastropoda) is also possible because it resembles the paraturbinid genus Chartronella. The characteristic Werfenella rectecostata–Natiria costata gastropod association from the Werfen Formation is not found in the approximately contemporaneous Sinbad Limestone of the Moenkopi Formation (Utah, USA) nor elsewhere outside Europe. This suggests that the similarities between Olenekian gastropod faunas from the Tethys and western North America are more limited than previously thought.
    Źródło:
    Acta Palaeontologica Polonica; 2005, 50, 1
    0567-7920
    Pojawia się w:
    Acta Palaeontologica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The fossil record of early tetrapods: Worker effort and the end-Permian mass extinction
    Autorzy:
    Bernard, E L
    Ruta, M.
    Tarver, J.E.
    Benton, M.J.
    Powiązania:
    https://bibliotekanauki.pl/articles/21312.pdf
    Data publikacji:
    2010
    Wydawca:
    Polska Akademia Nauk. Instytut Paleobiologii PAN
    Opis:
    It is important to understand the quality of the fossil record of early tetrapods (Tetrapoda, minus Lissamphibia and Amniota) because of their key role in the transition of vertebrates from water to land, their dominance of terrestrial faunas for over 100 million years of the late Palaeozoic and early Mesozoic, and their variable fates during the end−Permian mass extinction. The first description of an early tetrapod dates back to 1824, and since then discoveries have occurred at a rather irregular pace, with peaks and troughs corresponding to some of the vicissitudes of human history through the past two centuries. As expected, the record is dominated by the well−sampled sedimentary basins of Europe and North America, but finds from other continents are increasing rapidly. Comparisons of snapshots of knowledge in 1900, 1950, and 2000 show that discovery of new species has changed the shape of the species−level diversification curve, contrary to earlier studies of family−level taxa. There is, however, little evidence that taxon counts relate to research effort (as counted by numbers of publications), and there are no biasing effects associated with differential study of different time intervals through the late Palaeozoic and Mesozoic. In fact, levels of effort are apparently not related to geological time, with no evidence that workers have spent more time on more recent parts of the record. In particular, the end−Permian mass extinction was investigated to determine whether diversity changes through that interval might reflect worker effort: it turns out that most records of early tetrapod taxa (when corrected for duration of geological series) occur in the Lower Triassic.
    Źródło:
    Acta Palaeontologica Polonica; 2010, 55, 2; 229-239
    0567-7920
    Pojawia się w:
    Acta Palaeontologica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Taxonomy, nomenclature, and evolution of the early schubertellid fusulinids
    Autorzy:
    Davydov, V.
    Powiązania:
    https://bibliotekanauki.pl/articles/21821.pdf
    Data publikacji:
    2011
    Wydawca:
    Polska Akademia Nauk. Instytut Paleobiologii PAN
    Tematy:
    Carboniferous
    Eoschubertella
    Foraminifera
    Fusulinida
    Permian
    Schubertella
    Schubertellidae
    evolution
    nomenclature
    paleontology
    schubertellid fusulinid
    systematics
    taxonomy
    Opis:
    The types of the species belonging to the fusulinid genera Schubertella and Eoschubertella were examined from publications and type collections. Eoschubertella in general possesses all the features of Schubertella and therefore is a junior synonym of the latter. However, the concept of Eoschubertella best describes the genus Schubertina with its type species Schubertina curculi. Schubertina is closely related to the newly established genus Grovesella the concept of which is emended in this paper. Besides Schubertella, Schubertina, and Grovesella, the genera Mesoschubertella, Biwaella are reviewed and three new species, Grovesella nevadensis, Biwaella zhikalyaki, and Biwaella poletaevi, are described. The phylogenetic relationships of all Pennsylvanian–Cisuralian schubertellids are also proposed. Barrel−shaped Grovesella suggested being the very first schubertellid that appears sometimes in the middle–late Bashkirian time. In late Bashkirian it is then developed into ovoid to fusiform Schubertina. The latter genus gave rise into Schubertella in early Moscovian. First Fusiella derived from Schubertella in late Moscovian, Biwaella—in early Gzhelian and Boultonia—in late Gzhelian time. Genus Mesoschubertella also developed from Schubertella at least in Artinskian, but may be in late Sakmarian.
    Źródło:
    Acta Palaeontologica Polonica; 2011, 56, 1
    0567-7920
    Pojawia się w:
    Acta Palaeontologica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
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