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Wyszukujesz frazę "Hokkaidō" wg kryterium: Temat


Wyświetlanie 1-4 z 4
Tytuł:
Late Cretaceous record of large soft-bodied coleoids based on lower jaw remains from Hokkaido, Japan
Autorzy:
Tanabe, K.
Misaki, A.
Ubukata, T.
Powiązania:
https://bibliotekanauki.pl/articles/945495.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Late Cretaceous
Cretaceous
Cephalopoda
Coleoidea
Vampyromorpha
Teuthida
coleoid
jaw
remains
Hokkaido
Japan
Opis:
The origin and phylogenetic relationships of most modern coleoid groups have not yet been explained by reliable fossil evidence, in large part because of the reduction or disappearance of a calcified chambered shell during their evolutionary history. Herein we describe two exceptionally large coleoid lower jaws from the Upper Cretaceous strata in Hokkaido, Japan. On the basis of the comparison of gross morphology and morphometric data of the lower jaws of modern and fossil coleoids, we assigned the two lower jaws to the following new taxa: Nanaimoteuthis hikidai sp. nov. of the order Vampyromorpha (superorder Octobrachia) and Haboroteuthis poseidon gen. et sp. nov. of the order Teuthida (superorder Decabrachia). The lower jaw of N. hikidai is distinguished from other species of the same genus from the Upper Cretaceous of Vancouver Island (Canada) and Hokkaido by having a broader, more anteriorly curved hood of the outer lamella. The lower jaw of H. poseidon seemingly exhibits mosaic features like those of modern teuthids and sepiids but is assigned to Teuthida on the basis of the overall shape of the outer lamella and the development of a distinct fold on the lateral wall. Because of the unusually large lower jaws, these new taxa appear to be comparable in body size to modern giant squids (Architeuthis spp.) and the Humboldt squid (Dosidicus gigas). This and other discoveries of large jaws referable to octobrachian and decabrachian coleoids from the Upper Cretaceous strata of the North Pacific fill the gap in the relatively poor fossil record of mainly soft-bodied coleoids.
Źródło:
Acta Palaeontologica Polonica; 2015, 60, 1
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Gastropods from Late Cretaceous Omagari and Yasukawa hydrocarbon seep deposits in the Nakagawa area, Hokkaido, Japan
Autorzy:
Kaim, A
Jenkins, R.G.
Hikida, Y.
Powiązania:
https://bibliotekanauki.pl/articles/20568.pdf
Data publikacji:
2009
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
gastropod
Late Cretaceous
Cretaceous
Omagari
Yasukawa
hydrocarbon seep
deposit
Nakagawa area
Hokkaido
Japan
Gastropoda
Opis:
Sixteen gastropod species from two Campanian (Upper Cretaceous) hydrocarbon seep localities in Hokkaido, Japan are described. Seven species are new: the acmaeid limpet Serradonta omagariensis; three turbinids: Homalopoma abeshinaiensis, Cantrainea yasukawensis, and C. omagariensis; the trochid Margarites sasakii; the seguenzioid Cataegis nakagawensis; and the provannid Provanna nakagawensis. The most common species in the investigated localities are acmaeid limpets (S. omagariensis), tiny turbinids (H. abeshinaiensis, C. yasukawensis, C. omagariensis), and provannids/hokkaidoconchids (P. nakagawensis and Hokkaidoconcha hikidai). The Upper Cretaceous associations described here do not resemble Lower Cretaceous associations known from other regions but are composed of species similar to gastropods from Recent hydrocarbon seeps and hydrothermal vents in the Northwestern Pacific. This strongly suggest that this region possesses a regional pool of gastropods in chemosynthesis−based communities at least since Late Cretaceous time. The only group of gastropods described here which has no Recent counterpart is the Hokkaidoconchidae. A comparison to gastropods from plesiosaur falls and sunken wood of the same age and region strongly suggest that these invertebrate communities do not differ significantly from the coeval hydrocarbon seep communities described herein.
Źródło:
Acta Palaeontologica Polonica; 2009, 54, 3; 463-490
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Antiquity of the substrate choice among acmaeid limpets from Late Cretaceous chemosynthesis-based communities
Autorzy:
Jenkins, R G
Kaim, A.
Hikida, Y.
Powiązania:
https://bibliotekanauki.pl/articles/22869.pdf
Data publikacji:
2007
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Hokkaido
Gastropoda
Japan
fossil
Late Cretaceous
Cretaceous
methane-seep site
Bathyacmaea
Serradonta
paleoecology
chemosynthetic community
paleontology
Opis:
Two Campanian methane seep sites in the Nakagawa area of Hokkaido (northern Japan) yield fossils of the limpet genera Serradonta and Bathyacmaea that appear to have had the same substrate preference as do their modern counterparts. Serradonta cf. vestimentifericola was a species having an elongated and strongly compressed shell adapted to living on vestimentiferan tubes, like its modern relatives. Bathyacmaea cf. subnipponica was an acmaeid with a relatively elongated shell but with a more rounded aperture than Serradonta and thus apparently attached to small hard objects other than worm tubes. One Bathyacmaea specimen was found attached in situ to an ataphrid gastropod shell. The restricted present−day distribution of Serradonta possibly reflects its spreading route exclusively through the hot vent and cold seep communities settled by vestimentiferans.
Źródło:
Acta Palaeontologica Polonica; 2007, 52, 2
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Precursory siphuncular membranes in the body chamber of Phyllopachyceras and comparisons with other ammonoids
Autorzy:
Tanabe, K
Kulicki, C.
Landman, N.H.
Powiązania:
https://bibliotekanauki.pl/articles/22378.pdf
Data publikacji:
2005
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Ammonoidea
Late Cretaceous
organic membrane
scanning electron microscopy
morphogenesis
Hokkaido
body chamber
Japan
chamber formation
Phyllopachyceras ezoense
septal epithelium
paleontology
Phyllopachyceras
ammonoid
Opis:
Organic membranes preserved in the rear part of the body chamber of the Late Cretaceous phylloceratid ammonite Phyllopachyceras ezoense were examined with scanning electron microscopy (SEM) on the basis of well−preserved specimens from Hokkaido, Japan. SEM observations revealed that the membranes are continuous with the siphuncular tube wall in the phragmocone and consist of two layers, both of which are made of a dark, primarily conchiolin material; namely, a thinner inner homogeneous layer and a thicker outer layer with gently inclined pillar−like units. Hence, they are interpreted as the precursory siphuncular membranes. The precursory siphuncular membranes are not associated with any other organic components such as the siphuncular sheets reported in some Paleozoic and Mesozoic ammonoids. Unlike the tube−like condition in the phragmocone, the precursory siphuncular membranes in the body chamber of the specimens examined do not form a tube shape; on the ventral side the membranes are truncated and directly contact the outer shell wall. These observations suggest that the inner and outer layers of the precursory siphuncular membranes in the body chamber were respectively formed by the siphuncular epithelium from the inner side and by the invaginated septal epithelium from the outer side. It is also postulated that at the initial stage of septal formation, the rear part of the body moved slowly forward, developing a circumsiphonal invagination of the septal epithelium. Because similar conchiolin membranes are occasionally preserved in the body chambers of other phylloceratids, the above morphogenetic process applies to all members of the Phylloceratina. The tube−shaped structure in the rear part of the body chamber of desmoceratid Damesites consists only of nacreous layer. We interpret it as a pathologically overgrown prochoanitic septal neck.
Źródło:
Acta Palaeontologica Polonica; 2005, 50, 1
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
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