Informacja

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

Wyszukujesz frazę "dermal skeleton" wg kryterium: Wszystkie pola


Wyświetlanie 1-3 z 3
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:
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:
The squamation of “Ctenacanthus” costellatus (Chondrichthyes: Ctenacanthiformes) from the Carboniferous of Lublin area, south-eastern Poland
Autorzy:
Ginter, Michał
Skompski, Stanisław
Powiązania:
https://bibliotekanauki.pl/articles/138805.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Ctenacanthiformes
sharks
dermal skeleton
Viséan
Lublin Coal Basin
rekiny
szkielet skórny
wizen
Lubelskie Zagłębie Węglowe
Opis:
A sample of late Viséan limestone from the Włodawa IG-4 borehole, east of Lublin, Poland, yielded a piece of a tooth and a few hundred well-preserved scales comparable to those of “Ctenacanthus” costellatus Traquair, 1884 from Glencartholm, Scotland, UK. Most of the scales are typical compound body scales of the ctenacanthid type. Their crowns are composed of several separate odontodes whose distal ends are turned backwards and bases are characterised by concave undersides. In the material, there are also sparse scales with similar crowns but with flat or convex bulbous bases, as well as ornamented plates and single, star-like denticles, probably from the head region. The taxonomic status of “Ctenacanthus” costellatus was analysed and a new generic name for that species, viz. Glencartius gen. nov., is proposed.
Źródło:
Acta Geologica Polonica; 2019, 69, 4; 571-582
0001-5709
Pojawia się w:
Acta Geologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

    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