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Wyszukujesz frazę "Middle Ordovician" wg kryterium: Temat


Wyświetlanie 1-2 z 2
Tytuł:
First report on the occurrence of Neseuretinus and Ovalocephalus trilobites in the Middle Ordovician of Iran
Autorzy:
Ghobadi, Pour M
Popov, L.E.
Powiązania:
https://bibliotekanauki.pl/articles/21343.pdf
Data publikacji:
2009
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
trilobite
taxonomy
Trilobita
paleontology
Shirgesht Formation
Ovalocephalus
Neseuretinus
Ordovician
paleobiogeography
Middle Ordovician
Iran
Opis:
In the Derenjal Mountains of east Central Iran, the upper part of the Shirgesht Formation (uppermost Darriwilian) contains a distinct trilobite assemblage that includes Neseuretinus birmanicus and Ovalocephalus aff. obsoletus among others. Both genera were previously unknown in Iran. The occurrence of Ovalocephalus represents the earliest sign of westward taxon migration from China towards higher latitudes along the West Gondwanan margin, which may be related to global warming, after a short episode of cooler climate in the early to mid Darriwilian. Patterns of biogeographical distribution of Ovalocephalus and Neseuretinussuggest that Central Iran was part of an “overlap zone” where tropical and high latitude benthic taxa mingled.
Źródło:
Acta Palaeontologica Polonica; 2009, 54, 1; 125-133
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Enrolment in a Middle Ordovician agnostoid trilobite
Autorzy:
Bruton, D L
Nakrem, H.A.
Powiązania:
https://bibliotekanauki.pl/articles/22605.pdf
Data publikacji:
2005
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
trilobite
Trilobita
preservation
Agnostida
Middle Ordovician
Virginia
Ordovician
agnostoid trilobite
Edinburg Formation
life habit
Trinodus elspethi
paleontology
Opis:
Study of silicified material of Trinodus elspethi, from the Edinburg Formation, Virginia, USA, shows there is no gliding of distal parts of segments but an articulating furrow and opposing flange with prongs, acting as apodemes for muscle attachment, allowed cephalon and thorax to move as a single unit. Articulation between thorax and pygidium was more rigid with prongs from the thorax articulating in sockets on the pygidium. Support is given to the view that agnostoids lived partially enrolled with cephalon and pygidium gaping. They are unique in lacking an articulating half−ring between cephalon and thorax and the hinge joint is modified medially to provide an opening for what is interpreted as an exhalatory organ through which water passed during feeding and swimming. Peculiarities of the thorax are connected with the presence of only two thoracic segments articulating as a unit with distal tips directed anteriorly rather than posteriorly. Otherwise articulating half rings are present in the rest of the thorax and pygidium and lack of articulating facets is not unique. It is concluded that agnostoids can be shown to be trilobites.
Źródło:
Acta Palaeontologica Polonica; 2005, 50, 3
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-2 z 2

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