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Wyszukujesz frazę "Arthrodira" wg kryterium: Temat


Wyświetlanie 1-3 z 3
Tytuł:
Placoderms from the Lower Devonian “placoderm sandstone” of the Holy Cross Mountains, Poland with biostratigraphical and palaeobiogeographical implications
Autorzy:
SZREK, PIOTR
DUPRET, VINCENT
Powiązania:
https://bibliotekanauki.pl/articles/945951.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
placodermi
arthrodira
actinolepidoidei
palaeobiogeography
devonian
poland
holy cross mountains
Opis:
The siliciclastic sequence of the Lower Devonian of the southern part of the Holy Cross Mountains in Poland is renown for abundant vertebrate fossils, including ostracoderm, sarcopterygian, acanthodian, chondrichthyan, and placoderm remains. Study of the vertebrate assemblage from the “placoderm sandstone” from Podłazie Hill in the Holy Cross Mountains reveals that the remains belong to Kujdanowiaspis sp. among other unspecified actinolepids and brachythoracids. The Polish actinolepid material is characterised by sizes bigger than those of the Podolian specimens; this may be related to geographic variation. Owing to the proximity between Podolia and Holy Cross Mountains we suggest that Kujdanowiaspis sp. from the Holy Cross Mountains may be a refugee of some species of Kujdanowiaspis from the Lochkovian–Pragian of Podolia and/or from Spain. Some anterolateral plates provisionally assigned to Arthrodira indet. probably represent a new genus due to the high overlapping surface for median dorsal and anteroventrolateral plates.
Źródło:
Acta Palaeontologica Polonica; 2017, 62, 4; 789-800
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ornamentation of dermal bones of Placodermi from the Lower Devonian of Morocco as a measure of biodiversity
Autorzy:
Antczak, M.
Berkowski, B.
Powiązania:
https://bibliotekanauki.pl/articles/94702.pdf
Data publikacji:
2017
Wydawca:
Uniwersytet im. Adama Mickiewicza w Poznaniu
Tematy:
Arthrodira
interspecific variation
ontogeny
fishes
North Africa
zróżnicowanie międzygatunkowe
ontogeneza
ryby
Afryka Północna
Opis:
Dermal bones are formed early during growth and thus constitute an important tool in studies of ontogenetic and evolutionary changes amongst early vertebrates. Ornamentation of dermal bones of terrestrial vertebrates is often used as a taxonomic tool, for instance in Aetosauria, extant lungfishes (Dipnoi) and ray-finned fishes (Actinopterygii), for which it have been proved to be of use in differentiating specimens to species level. However, it has not been utilised to the same extent in placoderms. Several features of the ornamentation of Early Devonian placoderms from Hamar Laghdad (Morocco) were examined using both optical and scanning electron microscopy to determine whether it is possible to distinguish armoured Palaeozoic fishes. Four distinct morphotypes, based on ornamentation of dermal bones, are dif-ferentiated. These distinct types of ornamentation may be the result of either different location of dermal plates on the body or of ontogenetic (intraspecific) and/or interspecific variation.
Źródło:
Geologos; 2017, 23, 2; 65-73
1426-8981
2080-6574
Pojawia się w:
Geologos
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A preliminary note of egg-case oviparity in a Devonian placoderm fish
Autorzy:
Carr, R. K.
Jackson, G.
Powiązania:
https://bibliotekanauki.pl/articles/139073.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Devonian
Famennian
Cleveland Shale
Ohio
USA
Placodermi
Arthrodira
oviparity
egg case
Chondrichthyes
dewon
famen
ryby pancerne
tarczowce
plakodermy
zawiasowce
jajorodność
ryby chrzęstnoszkieletowe
ryby chrzęstne
chrzęstniki
Opis:
Six enigmatic fossils from the Famennian (Devonian) Cleveland Shale in Ohio, U.S.A., are interpreted here as arthrodiran (Placodermi) egg cases. Recognition as egg cases is confirmed based on the observation of layered collagen fibers. The presence of a tuberculated bone fragment preserved within one case confirms a vertebrate source. The nature of the tubercles and the unique morphology of the egg cases supports the interpretation of an arthrodiran source. Reports of Devonian egg cases are limited to either assumed chondrichthyan producers or a putative ‘egg sac’ with a morphology atypical for any vertebrate. The Cleveland Shale egg cases thus represent the first record for a non-chondrichthyan producer. Among placoderms, behaviors of a pelagic life style with obligate nesting sites, reef fishes with live birth, and estuarine and fluvial nurseries, along with eggcase oviparity testifies to the diversity of reproductive strategies. As with modern fishes these strategies may be ecologically driven and the derived and variable reproductive biology of extant chondrichthyans is actually a primitive condition among gnathostomes. One consequence of the diversity of reproductive strategies (dependent on the topology of relationships) is the independent origin of internal fertilization within placoderms, possibly suggesting external fertilization as the primitive gnathostome reproductive mode.
Źródło:
Acta Geologica Polonica; 2018, 68, 3; 381-389
0001-5709
Pojawia się w:
Acta Geologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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