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Wyszukujesz frazę "Oesia disjuncta" wg kryterium: Temat


Wyświetlanie 1-3 z 3
Tytuł:
The Burges Shale animal Oesia is not a chaetognath: A reply to Szaniawski [2005]
Autorzy:
Morris, S C
Powiązania:
https://bibliotekanauki.pl/articles/21841.pdf
Data publikacji:
2009
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
discussion
paleontology
Middle Cambrian
Burges Shale
Oesia disjuncta
chaetognath
Opis:
The Middle Cambrian Oesia disjuncta, a monospecific genus, is known only from the celebrated Burgess Shale of British Columbia. It has been re−interpreted by Szaniawski (Acta Palaeontologica Polonica 50:1–8; 2005) as a chaetognath, a distinctive phylum whose exact position in the protostomes is still controversial. Unequivocal chaetognaths, that have no similarity to Oesia, are already known to occur in the Chengjiang Lagerstätte (Lower Cambrian, S.W. China), and here I describe the first example of a chaetognath from the Burgess Shale itself. Comparisons between Oesia and chaetognaths fail to find any significant homologies. Whilst the phyletic position of Oesia is very uncertain, a place in the hemichordates may be worth exploring.
Źródło:
Acta Palaeontologica Polonica; 2009, 54, 1; 175-179
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Cambrian chaetognaths recognized in Burgess Shale fossils
Autorzy:
Szaniawski, H
Powiązania:
https://bibliotekanauki.pl/articles/20273.pdf
Data publikacji:
2005
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Oesia disjuncta
fossil
Burgess Shale
paleobiology
protoconodont
Canada
Cambrian
Chaetognatha
chaetognath
Opis:
Oesia disjuncta, one of the species of the soft−bodied fauna collected and described by Walcott (1911) from the Middle Cambrian Phyllopod Bed (Burgess Shale, British Columbia, Canada) is recognized as a chaetognath. For anatomical comparisons many specimens of Recent chaetognaths were specially compressed and dried to obtain forms similar to the fossils preserved in shales. The most characteristic features shared by the fossil and Recent specimens include: strongly elongated, transversely striated and very flexible body, large size, and characteristically diversified shape of head, pronounced intestine and horizontally oriented caudal fin. Possible traces of other chaetognath structures—grasping apparatus, lateral fins, seminal vesicles, ventral ganglion, ovaries and anus—are also present but preserved in one specimen only. Among extant genera, those showing the closest similarity to Oesia Walcott, 1911 are the hyperbenthic Archeterokrohnia Casanova, 1986¹, and Heterokrohnia Ritter−Záhony, 1911, which are considered by some authors as evolutionarily most primitive.
Źródło:
Acta Palaeontologica Polonica; 2005, 50, 1
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fossil chaetognaths from the Burgess Shale: A reply to Conway Morris [2009]
Autorzy:
Szaniawski, H
Powiązania:
https://bibliotekanauki.pl/articles/21244.pdf
Data publikacji:
2009
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
paleontology
chaetognath
fossil
new genus
new species
Middle Cambrian
Chaetognatha
Oesia disjuncta
polychaete annelid
Cambrian
Amiskwia sagittiformis
Opis:
Walcott (1911) erected the new genus and species Oesia disjuncta and assigned them to the polychaete annelids, based on a small collection of similar fossils from the famous Middle Cambrian Burgess Shale. In 2002 I suggested that the species is “possibly related to chaetognaths” (Szaniawski 2002: 405). Later, after obtaining new photos of the specimens and making comparative investigations with the extant chaetognaths, I was able to describe many significant similarities, and came to the conclusion that O. disjuncta indeed is an ancestral chaetognath (Szaniawski 2005). This interpretation already has been accepted in several publications (Vannier et al. 2005; Ball and Miller 2006; Hu et al. 2007. Giribet 2008). Ball and Miller (2006: 594) confirmed not only its “... remarkable resemblance to modern chaetognaths” but also correctness of recognition of all its organs. They even reproduced a part of my illustration showing them (Ball and Miller 2006: fig. 2). Vannier et al. (2006: 629) combined the problem with the open question of the systematic position of another Burgess Shale fossil Amiskwia sagittiformis Walcott, 1911, and expressed their reservation based on “...the lack of clear evidence of a grasping apparatus...”. Only Conway Morris (2009) firmly disagreed with this diagnosis and even devoted a special “discussion” article addressing the issue. However, that article contains several ambiguities and misunderstandings which need clarification.
Źródło:
Acta Palaeontologica Polonica; 2009, 54, 2; 361-364
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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