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    Wyświetlanie 1-7 z 7
    Tytuł:
    Early ontogeny of Jurassic bakevelliids and their bearing on bivalve evolution
    Autorzy:
    Malchus, N
    Powiązania:
    https://bibliotekanauki.pl/articles/22830.pdf
    Data publikacji:
    2004
    Wydawca:
    Polska Akademia Nauk. Instytut Paleobiologii PAN
    Tematy:
    phylogenesis
    Pteriomorphia
    Bakevelliidae
    shell
    bakevelliid
    larva shell
    Jurassic
    bivalve
    ontogenesis
    Bivalvia
    evolution
    larva
    paleontology
    Opis:
    Larval and earliest postlarval shells of Jurassic Bakevelliidae are described for the first time and some complementary data are given concerning larval shells of oysters and pinnids. Two new larval shell characters, a posterodorsal outlet and shell septum are described. The outlet is homologous to the posterodorsal notch of oysters and posterodorsal ridge of arcoids. It probably reflects the presence of the soft anatomical character post−anal tuft, which, among Pteriomorphia, was only known from oysters. A shell septum was so far only known from Cassianellidae, Lithiotidae, and the bakevelliid Kobayashites. A review of early ontogenetic shell characters strongly suggests a basal dichotomy within the Pteriomorphia separating taxa with opisthogyrate larval shells, such as most (or all?) Praecardioida, Pinnoida, Pterioida (Bakevelliidae, Cassianellidae, all living Pterioidea), and Ostreoida from all other groups. The Pinnidae appear to be closely related to the Pterioida, and the Bakevelliidae belong to the stem line of the Cassianellidae, Lithiotidae, Pterioidea, and Ostreoidea. The latter two superfamilies comprise a well constrained clade. These interpretations are consistent with recent phylogenetic hypotheses based on palaeontological and genetic (18S and 28S mtDNA) data. A more detailed phylogeny is hampered by the fact that many larval shell characters are rather ancient plesiomorphies.
    Źródło:
    Acta Palaeontologica Polonica; 2004, 49, 1
    0567-7920
    Pojawia się w:
    Acta Palaeontologica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Early ontogeny and palaeoecology of the Mid-Miocene rissoid gastropods of the Central Paratethys
    Autorzy:
    Kowalke, T
    Harzhauser, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/21635.pdf
    Data publikacji:
    2004
    Wydawca:
    Polska Akademia Nauk. Instytut Paleobiologii PAN
    Tematy:
    Miocene
    gastropod
    Mohrensternia pfaffstaettensis
    morphology
    embryonic shell
    Sarmatian
    Mohrensternia hollabrunnensis
    Gastropoda
    ontogenesis
    Caenogastropoda
    rissoid gastropod
    Badenian
    paleoecology
    Rissooidea
    Littorinimorpha
    Opis:
    Twenty−six species of Rissoidae (Caenogastropoda: Littorinimorpha: Rissooidea) are described from the Badenian and Early Sarmatian of 14 localities in Austria and the Czech Republic (Molasse Basin, Styrian Basin, Vienna Basin) and from the Badenian of Coştei (Romania). For the first time, the early ontogenetic skeletal characters of these gastropods are described. Based on these features an indirect larval development with a planktotrophic veliger could be reconstructed for all investigated Mid−Miocene species. The status of Mohrensterniinae as a subfamily of the Rissoidae is confirmed by the morphology of the low conical protoconch, consisting of a fine spirally sculptured embryonic shell and a larval shell which is smooth except for growth lines. Transitions from embryonic shells to larval shells and from larval shells to teleoconchs are slightly thickened and indistinct. Whilst representatives of the subfamily Rissoinae characterise the marine Badenian assemblages, Mohrensterniinae predominate the Early Sarmatian faunas. We hypothesize that this take−over by the Mohrensterniinae was triggered by changes in the water chemistry towards polyhaline conditions. Consequently, the shift towards hypersaline conditions in the Late Sarmatian is mirrored by the abrupt decline of the subfamily. Four new species Rissoa costeiensis (Rissoinae) from the Badenian and Mohrensternia hollabrunnensis, Mohrensternia pfaffstaettensis, and Mohrensternia waldhofensis (Mohrensterniinae) from the Early Sarmatian are introduced.
    Źródło:
    Acta Palaeontologica Polonica; 2004, 49, 1
    0567-7920
    Pojawia się w:
    Acta Palaeontologica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Early ontogenetic growth stages of Middle Ordovician orthoceratoid cephalopods from Bohemia
    Autorzy:
    Aubrechtova, M.
    Turek, V.
    Zicha, O.
    Powiązania:
    https://bibliotekanauki.pl/articles/2082221.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Instytut Paleobiologii PAN
    Tematy:
    Cephalopoda
    Orthoceratida
    early ontogeny
    embryonic shell
    Paleozoic
    Darriwilian
    Bohemia
    Czech
    Republic
    Opis:
    This study describes 18 specimens representing the earliest growth parts of orthoceratoid cephalopods, most of which have been recently obtained from the Middle Ordovician strata of the Prague Basin, central Bohemia. Only about 20 specimens of Ordovician orthoceratoids displaying embryonic shell are known globally and the Bohemian material thus significantly expands their current record. The studied collection includes twelve specimens assigned to the species Bactroceras sandbergeri and shows that the morphological variability in early ontogenetic growth stages of this species was rather low. The absence of a cicatrix was definitely confirmed in this phylogenetically important cephalopod. Six other specimens investigated herein are indeterminate orthoceratids. Initial chambers, where preserved, are generally large compared to known, stratigraphically younger specimens. This is interpreted here as supporting the previously postulated trend of decreasing the egg- and hatchling sizes in orthoceratoid cephalopods from mid-Ordovician times onwards. Alternatively, the large sizes of these Bohemian orthoceratids may be explained by the position of the Prague Basin in relatively cool-water high palaeolatitudes during the Middle Ordovician.
    Źródło:
    Acta Palaeontologica Polonica; 2020, 65, 3; 575-588
    0567-7920
    Pojawia się w:
    Acta Palaeontologica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Postcranial osteology of the first early-stage juvenile skeleton of Plateosaurus trossingensis from the Norian of Frick, Switzerland
    Autorzy:
    Nau, D.
    Lallensack, J.N.
    Bachmann, U.
    Sander, P.M.
    Powiązania:
    https://bibliotekanauki.pl/articles/2082237.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Instytut Paleobiologii PAN
    Tematy:
    Dinosauria
    Sauropodomorpha
    morphometrics
    morphology
    small body size
    early ontogeny
    Triassic
    Swiss Plateau
    Opis:
    Owing to monospecific mass-accumulation sites in Central Europe, the early-branching sauropodomorph Plateosaurus has one of the best fossil records among dinosaurs. Despite this, early-stage juveniles have been conspicuously absent. However, such specimens are critical in assessing the ontogenetic development of this taxon, as well as the role of heterochrony in sauropodomorph evolution. A new skeleton from the Plateosaurus bonebed at the Gruhalde Quarry (Klettgau Formation, Norian) of Frick, Switzerland, nicknamed “Fabian”, represents the first substantially complete juvenile referrable to Plateosaurus. The specimen includes large portions of the cranium and vertebral column and an almost completely represented appendicular skeleton. Its juvenile ontogenetic stage is confirmed by a lack of neurocentral suture fusion in the axial skeleton. Consistent with this, the estimated total length and body mass of approximately of 2.3 m and 40 kg are considerably smaller than any previously reported specimen of the genus. Surprisingly, the postcranial morphology of the specimen is remarkably consistent with that of osteologically mature individuals, including a virtually fully developed pattern of laminae and fossae in the vertebrae. Comparisons of body proportions are complicated by varying degrees of compaction in the limb elements, but skeletal proportions mostly appear to follow isometry, with the notable exceptions of a relatively long neck, proportionately larger manus, shorter, more gracile humerus and shorter forearm in the juvenile specimen. The observed morphology suggests that adult morphology was either achieved early in ontogeny of Plateosaurus, or alternatively that developmental plasticity, which has previously been found to result in high variability of adult body size, could potentially also extend to morphological development.
    Źródło:
    Acta Palaeontologica Polonica; 2020, 65, 4; 679-708
    0567-7920
    Pojawia się w:
    Acta Palaeontologica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Phyllotactic pattern formation in early stages of cactus ontogeny
    Autorzy:
    Gola, E M
    Powiązania:
    https://bibliotekanauki.pl/articles/59078.pdf
    Data publikacji:
    2006
    Wydawca:
    Polskie Towarzystwo Botaniczne
    Tematy:
    phyllotactic transformation
    pattern formation
    early stage
    cactus
    Cactaceae
    ontogenesis
    phyllotaxis
    Opis:
    Representatives of the family Cactaceae are characterized by a wide range of phyllotaxis. To assess the origin of this diversity, early stages of phyllotactic pattern formation were examined in seedlings. The analysis of the sequence of areole initiation revealed intertribal differences. In seedlings from the Trichocereeae (Gymnocalycium, Rebutia) and Notocacteae (Parodia) tribes, two opposite cotyledonal areoles developed as the first elements of a pattern. Usually, next pair of areoles was initiated perpendicularly to cotyledonal areoles, starting the decussate pattern. This pattern was subsequently transformed into bijugate or into simple spiral phyllotaxis. In seedlings from the Cacteae tribe (Mammillaria and Thelocactus), cotyledonal areoles were never observed and the first areoles always appeared in the space between cotyledons. It was either areole pair (mainly in Mammillaria), starting a decussate pattern, or a single areole (mainly in Thelocactus) quickly followed by areoles spirally arranged, usually in accordance with the main Fibonacci phyllotaxis. Differences in the initial stages of pattern formation do not fully explain the phyllotaxis diversity in mature cacti. Only two, the most common phyllotactic patterns occurred in the early development of studied seedlings, i.e. the main Fibonacci and the decussate pattern. Discrepancy in the range of phyllotactic spectra in seedlings and in mature plants suggests that phyllotaxis diversity emerges during further plant growth. Initial phyllotactic transformations, occurring already in the very early stages, indicate great plasticity of cactus growth and seem to support the hypothesis of the ontogenetic increase of phyllotaxis diversity due to transformations.
    Źródło:
    Acta Societatis Botanicorum Poloniae; 2006, 75, 4; 271-279
    0001-6977
    2083-9480
    Pojawia się w:
    Acta Societatis Botanicorum Poloniae
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Ontogeny and autecology of an Early Cretaceous trigoniide bivalve from Neuquén Basin, Argentina
    Autorzy:
    Echevarria, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/945794.pdf
    Data publikacji:
    2014
    Wydawca:
    Polska Akademia Nauk. Instytut Paleobiologii PAN
    Tematy:
    mollusca
    bivalvia
    trigoniida
    ontogeny
    larval development
    shell growth
    allometry
    life habits
    cretaceous
    argentina
    Opis:
    Understanding ontogenetic variation is fundamental for adequate species definition and is the key for recognizing evolutionary relevant processes like heterochrony or developmental constraints. The larval and post-larval shell ontogeny and the ecology of the trigoniide bivalve Myophorella garatei are described in this paper. The species occurs in offshore transition facies of the late Valanginian Pilmatué Member of the Agrio Formation in the Neuquén Basin, Argentina. The larval shell has a rather small prodissoconch I; and if prodissoconch II is present, it is rather weakly developed. From these data, a larval stage of low dispersal capability is inferred for Myophorella garatei, either short-lived planktotrophic or nonplanktotrophic. The study of post-larval development included general shell shape and ornamentation. To assess general shell shape a geometric morphometric analysis was performed on the lateral view, together with a study of allometry for the shell width. As a result, two main allometric stages of development could be identified. During the first stage a relative size reduction of the area co-occurs with a slight elongation of the shell, while the second stage is marked by dorsal bending of the shell and an increase on relative width. Ornamentation was examined qualitatively, but also a geometric morphometric analysis was performed on the flank costae. The first two flank costae are subconcentric; from the third costa onwards they become oblique, intially changing from more curved to less curved shapes, while on a third stage they show the opposite trend. Finally, a general interpretation of the adaptive morphology of adult shell was performed, concluding that M. garatei was adapted to low energy, soft bottom environments, and probably lived with the posterior straight margin levelled at the water-sediment interface.
    Źródło:
    Acta Palaeontologica Polonica; 2014, 59, 2; 407-420
    0567-7920
    Pojawia się w:
    Acta Palaeontologica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Growth in early species of the conodont Ancyrodella and implications for correlation of the Middle-Upper Devonian boundary
    Autorzy:
    Miller, C.G.
    Powiązania:
    https://bibliotekanauki.pl/articles/2059511.pdf
    Data publikacji:
    2007
    Wydawca:
    Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
    Tematy:
    conodonts
    Devonian
    Givetian
    Frasnian
    Ancyrodella
    ontogeny
    Opis:
    The first occurrence of the conodont Ancyrodella rotundiloba has been used extensively for correlating the Middle-Up per Devonian (Givetian-Frasnian) boundary in sections worldwide despite many arguments as to its precise taxonomic definition. These arguments are summarised herein and three ontogenetic series illustrated from three samples across the Givetian-Frasnian boundary within the Vorota Formation of the Kozhym River section, Sub-Polar Urals, Russia. General trends within the three ontogenetic series suggest that the ratio of basal pit width to platform width in Ancyrodella pristina, and Ancyrodella recta in creases through ontogeny but the morphology of lateral secondary keel extensions to the basal pit remains constant and is a useful taxonomic feature. Folds and collars on the basal surface occur only in the later stages of development. The out line of the platform within species is variable and controlled by the formation of incipient nodes in juveniles; gerontic specimens can also have very variable platform out lines. Measure ments of platform width to basal pit width ratios and platform shape out lines may not therefore be a good way to compare between species. The three ontogenetic series provide typical late Givetian and early Frasnian examples and increase the potential for correlation of the Middle-Upper Devonian boundary particularly using juvenile Ancyrodella specimens.
    Źródło:
    Geological Quarterly; 2007, 51, 4; 443-452
    1641-7291
    Pojawia się w:
    Geological Quarterly
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-7 z 7

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