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    Tytuł:
    A microanatomical and histological study of the postcranial dermal skeleton in the Devonian sarcopterygian Eusthenopteron foordi
    Autorzy:
    Zylberberg, L
    Meunier, F.J.
    Laurin, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/20289.pdf
    Data publikacji:
    2010
    Wydawca:
    Polska Akademia Nauk. Instytut Paleobiologii PAN
    Tematy:
    paleontology
    microanatomical study
    histology
    postcranial dermal skeleton
    Devonian
    sarcopterygian
    Eusthenopteron foordi
    Sarcopterygii
    Tetrapodomorpha
    Tristichopteridae
    Eusthenopteron
    elasmoid scale
    paleohistology
    transmission electron microscopy
    Late Devonian
    Frasnian
    fossil record
    Opis:
    The fin rays and two types of scales (enlarged and regular) of the Devonian sarcopterygian Eusthenopteron foordi are redescribed using light, scanning and transmission electron microscopy. The fin rays consist of lepidotrichia composed of ossified, jointed and branched segment pairs. The basal segments are cylindrical, but more distal elements are crescentic in section. The distribution of Sharpey’s fibres varies along the lepidotrichia. In the proximal segments, lateral bundles form a belt connecting adjacent hemisegments. In the distal segments, thin bundles are restricted to the area facing the fin surface. Both enlarged and regular scales have a similar spatial organisation. They are composed of a superficial highly mineralised layer covering a thick basal plate where the fibrils are distributed in superimposed strata forming a plywood−like structure. Nevertheless, the enlarged and regular scales differ in their shape, in the mineralised tissues of the superficial layer, and in the organisation of the plywood−like structure. The superficial layer of the enlarged scales is composed of parallel−fibered bone covering a deeper layer of woven−fibered bone. The basal plate is made of an orthogonal plywood−like structure. The thin, lamellar, imbricated regular scales display the characteristics of elasmoid scales. The mineralised tissue forming the superficial layer resembles that of extant teleost scales. In the basal plate, the twisted plywood−like structure is composed of closely packed fibrils that are preserved down to the ultrastructural level owing to the persistence of bridges connecting the fibrils. The enlarged and the regular scales of Eusthenopteron foordi do not present superficial odontodes, in contrast to ancestral thick rhomboid scales. The disappearance of enamel/enameloid and dentine may be related to the evolutionary trend towards a lightening of the dermal skeleton that would improve the swimming abilities of the animal. The characteristics of the dermal skeleton of Eusthenopteron foordi support the hypothesis that this process began early in osteichthyans.
    Źródło:
    Acta Palaeontologica Polonica; 2010, 55, 3; 459-470
    0567-7920
    Pojawia się w:
    Acta Palaeontologica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Osteoderm histology of Late Pleistocene cingulates from the intertropical region of Brazil
    Autorzy:
    Da Costa Pereira, P.V.L.G.
    Victer, G.D.
    Porpino, K.O.
    Bergqvist, L.P.
    Powiązania:
    https://bibliotekanauki.pl/articles/945892.pdf
    Data publikacji:
    2014
    Wydawca:
    Polska Akademia Nauk. Instytut Paleobiologii PAN
    Tematy:
    osteoderm
    histology
    Late Pleistocene
    Pleistocene
    Cingulata
    mammalia
    Glyptodontidae
    Pachyarmatherium
    paleohistology
    intertropical region
    Brazil
    Opis:
    During the Late Pleistocene, several possibly endemic cingulate species, known mostly from isolated osteoderms, carapace fragments, and caudal tubes, coexisted in the Brazilian Intertropical Region. Here, we describe the osteoderm microstructure of Pachyarmatherium brasiliense, as well as the glyptodonts Panochthus greslebini, Panochthus jaguaribensis and Glyptotherium sp., in order to provide additional species-diagnostic characters and shed light on their evolutionary relationships. Pachyarmatherium brasiliense lacks several derived features shared by glyptodonts and pampatheres, such as extensive bone remodeling, fibers arranged in large bundles, and relatively poorly developed layers of compact bone, thus supporting its exclusion from glyptodonts as suggested by a recent cladistic study. The osteoderm histology of P. greslebini resembles that of other species of Panochthus (e.g., Panochthus frenzelianus). By contrast, the presence of relatively thick layers of compact bone, the configuration and size of resorption areas, the absence of randomly oriented lateral fiber bundles, and the absence of an intermediary region between the compact and trabecular bone potentially support the exclusion of Panochthus jaguaribensis from the genus. Finally, osteoderms of the Brazilian specimens of Glyptodontinae share histological features with Glyptotherium floridanus, rather than Glyptodon, thus reinforcing their assignment to Glyptotherium. These results highlight the relevance of histological osteoderm characters in cingulate systematics, ands call for further and more comprehensive studies.
    Źródło:
    Acta Palaeontologica Polonica; 2014, 59, 3; 543-552
    0567-7920
    Pojawia się w:
    Acta Palaeontologica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A microanatomical and histological study of the postcranial dermal skeleton of the Devonian actinopterygian Cheirolepis canadensis
    Autorzy:
    Zylberberg, L.
    Meunier, F.J.
    Laurin, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/20617.pdf
    Data publikacji:
    2016
    Wydawca:
    Polska Akademia Nauk. Instytut Paleobiologii PAN
    Tematy:
    microanatomical study
    histology
    postcranial dermal skeleton
    Devonian
    actinopterygian
    Actinoterygia
    Cheirolepis
    ganoine
    dentine
    paleohistology
    Canada
    Cheirolepis canadensis
    Opis:
    The Devonian stem-actinoterygian Cheirolepis canadensis is potentially important to understand the evolution of the dermal skeleton of osteichthyans, but the last detailed histological study on this taxon was published more than forty years ago. Here, we present new data about the morphology and the histological structure of scales, fulcra, and fin-rays in the Devonian actinopterygian Cheirolepis canadensis through SEM and photomicroscopy. The scales have a typical palaeoniscoid organisation, with ganoine layers overlaying dentine and a bony basal plate, but the ganoine surface lacks the characteristic microtubercles that have been described on the ganoine surface of the scales of polypterids and many other actinopterygians. Fin-rays are composed of segmented and ramified lepidotrichia that show a structure reminiscent of scales, with ganoine and dentine components lying on a thick bony base. We describe articular processes between lepidotrichia that are reminiscent of, and plausibly homologous with, the peg-and-socket articulations between the scales. The analysis of the postcranial dermal skeleton of Cheirolepis canadensis shows that structural similarities between scales and lepidotrichia of this basal actinopterygian are greater than in more recent actinopterygians. The new data on histological and microanatomical structure of the dermal skeleton lend additional support to the hypothesis that lepidotichia are derivatives of scales, though they are also compatible with the more general hypothesis that scales, lepidotrichia and fulcra belong to the same morphogenetic system.
    Źródło:
    Acta Palaeontologica Polonica; 2016, 61, 2
    0567-7920
    Pojawia się w:
    Acta Palaeontologica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Unusual shell anatomy and osteohistology in a new Late Cretaceous panchelid turtle from northwestern Patagonia, Argentina
    Autorzy:
    DE LA FUENTE, MARCELO S.
    MANIEL, IGNACIO
    JANNELLO, JUAN MARCOS
    STERLI, JULIANA
    GARRIDO, ALBERTO C.
    GARCIA, RODOLFO A.
    SALGADO, LEONARDO
    CANUDO, JOSÉ I.
    BOLATTI, RAÚL
    Powiązania:
    https://bibliotekanauki.pl/articles/945623.pdf
    Data publikacji:
    2017
    Wydawca:
    Polska Akademia Nauk. Instytut Paleobiologii PAN
    Tematy:
    testudines
    pleurodira
    post-cranial morphology
    paleohistology
    cretaceous
    argentina
    río negro
    Opis:
    Rionegrochelys caldieroi de la Fuente, Maniel, and Jannello gen. et sp. nov. is a Late Cretaceous turtle from Rio Negro Province, Argentina. The holotype and the referred specimens of this new species show an unusual shell morphology and microanatomy. The proportion between the carapace and plastron and the peculiar morphology of the shell such as the heart shaped carapace, a very deep nuchal notch, peripheral bones 2–11 with strongly gutter, the first vertebral scute twice as wide as long and subrectangular in shape, the posterior margin of vertebral scute 5 is three lobe shaped, and the unexpected osteohistology characterized by a massive structure, with higher compactness (80.6%) than other chelids, suggests beyond doubt that this turtle may be considered a new taxon. A semi-aquatic habitat with tendency towards terrestrial environments is inferred for Rionegrochelys caldieroi similar to that of the extant pelomedusid Pelomedusa subrufa among the extant pleurodires. Rionegrochelys caldieroi is recovered as a stem chelid. This new species seems to be closely related to Bonapartemys bajobarrealis and the clade formed by Lomalatachelys neuquina plus Mendozachelys wichmanni.
    Źródło:
    Acta Palaeontologica Polonica; 2017, 62, 3; 585-601
    0567-7920
    Pojawia się w:
    Acta Palaeontologica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Comparative bone microstructure of three archosauromorphs from the Carnian, Late Triassic Chanares Formation of Argentina
    Autorzy:
    Marsa, J.A.G.
    Agnolin, F.L.
    Novas, F.E.
    Powiązania:
    https://bibliotekanauki.pl/articles/2082158.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Instytut Paleobiologii PAN
    Tematy:
    Archosauromorpha
    Lagerpeton
    Tropidosuchus
    paleobiology
    paleohistology
    Mesozoic
    South America
    Opis:
    The Chañares Formation exhibits one of the most important archosauriform records of early Carnian ecosystems. Here we present new data on the palaeohistology of Chañares archosauriforms and provide new insights into their paleobiology, as well as possible phylogenetically informative traits. Bone microstructure of Lagerpeton chanarensis and Tropidosuchus romeri is dominated by fibro-lamellar tissue and dense vascularization. On the other hand, Chanaresuchus bonapartei is more densely vascularized, but with cyclical growth characterized by alternate fibro-lamellar, parallel-fibered and lamellar-zonal tissues. Dense vascularization and fibro-lamellar tissue imply fast growth and high metabolic rates for all these taxa. These histological traits may be tentatively interpreted as a possible adaptative advantage in front of Chañares Formation environmental conditions.
    Źródło:
    Acta Palaeontologica Polonica; 2020, 65, 2; 387-398
    0567-7920
    Pojawia się w:
    Acta Palaeontologica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Growth dynamics and body size evolution of South American long-necked chelid turtles: A bone histology approach
    Autorzy:
    Pereyra, M.E.
    Bona, P.
    Cerda, I.A.
    Jannello, J.M.
    De La Fuente, M.S.
    Desantolo, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/2082231.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Instytut Paleobiologii PAN
    Tematy:
    Testudines
    Chelidae
    growth rate
    body size
    paleohistology
    ontogeny
    Paleocene
    Argentina
    Opis:
    Among turtles, cases of “gigantism” occur mostly in pleurodiran Pelomedusoides and cryptodirans, but are infrequent among pleurodiran chelids, which are mostly small-medium sized turtles. Yaminuechelys spp. are extinct South American long-necked chelids (from the Late Cretaceous–early Paleocene of Patagonia, Argentina) with caparaces almost three times larger than their extant sister taxon, Hydromedusa tectifera. Since evolutionary changes in size can be analyzed based on growth dynamics, we studied growth strategies from an osteohistological point of view. We sampled both extinct (Yaminuechelys maior) and extant (H. tectifera) species, in order to test hypotheses related to the mechanisms involved in the macroevolution of size within this clade. For this purpose, thin sections of long bone (humerus and femur) shafts of specimens of different ontogenetic stages for these species were prepared. The osteohistological study reveals a similar growth dynamic in both taxa, with a poorly vascularized cortex dominated by parallel- fibered bone and interrupted by lines of arrested growth (LAGs). The huge body size of Y. maior appears to be a consequence of the prolongation of the growth phase, suggesting that it had a longer lifespan than H. tectifera, allowing to reach greater sizes. In this way, and assuming that there is no displacement at the beginning of development (e.g., a delay in the earliest stages of growth) in H. tectifera, the acquisition of a large size in Yaminuechelys would be explained by hypomorphosis of the former or hypermorphosis of the latter, depending on the reconstruction of the ancestral condition of this clade.
    Źródło:
    Acta Palaeontologica Polonica; 2020, 65, 3; 535-545
    0567-7920
    Pojawia się w:
    Acta Palaeontologica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-6 z 6

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