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Wyszukujesz frazę "Lower Triassic" wg kryterium: Temat


Wyświetlanie 1-3 z 3
Tytuł:
The pustulated temnospondyl revisited - a plagiosternine plagiosaurid from the Lower Triassic of Brasil
Autorzy:
Dias-Da-Silva, S
Milner, A.R.
Powiązania:
https://bibliotekanauki.pl/articles/23465.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
temnospondyl
plagiosternine plagiosaurid
Lower Triassic
Triassic
paleontology
Brazil
plagiosaurid
systematics
morphology
Opis:
A recent contribution published in this journal (Dias−daSilva and Ilha 2009) reported a dermal skull fragment indicating the presence of a putative plagiosauroid temnospondyl in the Lower Triassic Sanga do Cabral Formation of the Paraná Basin, Southern Brazil. The taxonomic assignation of this specimen was necessarily tentative as it was based on circumstantial evidence, specifically the presence of a dense pustular ornamentation over four partial dermal skull bones, consideration of the described taxa known to bear such ornamentation, and the stratigraphic and paleobiogeographic range of such taxa. Therefore, Diasda−Silva and Ilha (2009) could not be totally certain about the plagiosauroid affinities of the new specimen and ascribed it to ?Plagiosauridae. It was particularly difficult to make a precise osteological identification of the specimen and six alternative osteological interpretations were made in comparison to both Gerrothorax and Peltobatrachus (see Dias−da−Silva and Ilha 2009: fig. 2). In spite of the poor taxonomic resolution, the new specimen raised interesting questions regarding the presence of plagiosauroid stereospondyls in western Gondwana, as well as their evolutionary patterns, biostratigraphic and paleobiogeographic implications. After Dias−da−Silva and Ilha's (2009) contribution was published, new data from Damiani et al. (2009) raised the possibility of narrowing down the taxonomic identity of the plagiosauroid from Brazil. Accordingly, this brief report provides a more precise taxonomic assignation for this material.
Źródło:
Acta Palaeontologica Polonica; 2010, 55, 3; 561-563
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An enigmatic chondrichthyan with Paleozoic affinities from the Lower Triassic of Western Canada
Autorzy:
Mutter, R J
Neuman, A.G.
Powiązania:
https://bibliotekanauki.pl/articles/19949.pdf
Data publikacji:
2006
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
histology
fish
Triassic
Lower Triassic
Paleozoic
Canada
chondrichthyan
paleontology
Listracanthus pectenatus
Western Canada
Opis:
Listracanthus pectenatus sp. nov. represents the youngest record of the enigmatic chondrichthyan Listracanthus. This new species is the only Mesozoic record of this genus and highlights survival of a rare and enigmatic group of cartilaginous fishes across the Paleozoic–Mesozoic boundary. In the Vega−Phroso Siltstone Member of the Sulphur Mountain Formation (western Canada), two kinds of numerous dermal denticles identified as Listracanthus occur predominantly in strata probably of early Smithian age. The new species differs from all other known species of the genus in the structure of the anterior and posterior borders of the large denticles. The small denticles appear to be less diagnostic than the large ones and are readily distinguished from small denticles generally assigned to the genus Petrodus. Histology reveals that the largest denticles were originally hollow, probably secondarily ossified as acellular bone. The conclusion drawn by previous authors that Listracanthus may be a petalodontid shark, based on ambiguous non−skeletal associations with Deltoptychius, Petrodus, or Calopodusis not supported by this study. The large number of denticles, the size of both types of denticles and their arrangement suggest that Listracanthus pectenatus sp. nov. was a large chondrichthyan of aberrant body shape and yet uncertain systematic position.
Źródło:
Acta Palaeontologica Polonica; 2006, 51, 2
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The brachyopoid Hadrokkosaurus bradyi from the early Middle Triassic of Arizona, and a phylogenetic analysis of lower jaw characters in temnospondyl amphibians
Autorzy:
Ruta, M.
Bolt, J.R.
Powiązania:
https://bibliotekanauki.pl/articles/21195.pdf
Data publikacji:
2008
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
brachyopoid
Hadrokkosaurus bradyi
Early Middle Triassic
Triassic
Arizona
phylogenetic analysis
lower jaw
temnospondyl amphibian
amphibian
Temnospondyli
Chigutisauridae
evolution
paleontology
holotype
Opis:
The holotype of the brachyopoid temnospondyl Hadrokkosaurus bradyi, represented by a right lower jaw ramus, is re−examined based upon new data and revision of various morphological features. Additional fragmentary jaw material referred to this species is briefly described. Prominent features are a large postsymphyseal foramen that is anteriorly open, and prearticular and surangular buttresses for support of the articular. Brachyopoid characters include a long and robust postglenoid area formed by surangular and prearticular, anterior and posterior keels on at least some marginal dentary teeth, and subtriangular outline of the adductor fossa in dorsal view. Five features of the holotype ramus, long thought to be at odds with its brachyopoid or temnospondyl nature, are critically re−evaluated. A phylogenetic analysis of lower jaw characters in temnospondyls retrieves most of the clades found in more comprehensive data sets, but the statistical node support is low. Brachyopoids are monophyletic, with Hadrokkosaurus emerging as their most basal taxon.
Źródło:
Acta Palaeontologica Polonica; 2008, 53, 4
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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