瑞浪市化石博物館研究報告
Online ISSN : 2435-0931
Print ISSN : 0385-0900
最新号
選択された号の論文の5件中1~5を表示しています
  • Stephen K. Donovan, Ben Dixon, Fiona E. Fearnhead
    2024 年 51 巻 1 号 p. 1-4
    発行日: 2024/05/17
    公開日: 2024/05/17
    研究報告書・技術報告書 オープンアクセス
    Identifiable crinoids are rare in the Devonian of the South Devon Basin, south-west England (UK). Hitherto, only two taxa have been described, both in open nomenclature, namely Ctenocrinus? spp. (Lower Devonian) and a twenty-armed camerate sp. indet. (Upper Devonian). A new collection, labelled ‘Lower Devonian’ and ‘unidentified crinoid stems’, is described here in slates from Trevone, near Padstow, north Cornwall. Three out of seven specimens are orthoconic nautiloids, not echinoderms. The crinoid gen. et sp. indet. is represented by pluricolumnals; there are no disarticulated ossicles, suggesting that burial was rapid. Some specimens on the largest slab are parallel, likely due to current-induced orientation. Autotomy may have released the crowns due to an environmental disturbance, leaving the columns to be buried locally.
  • Àlex Ossó, Barry W. M. van Bakel, Pedro Artal, José Luis Domínguez
    2024 年 51 巻 1 号 p. 5-14
    発行日: 2024/05/17
    公開日: 2024/05/17
    研究報告書・技術報告書 オープンアクセス
    A new species of Distefania Checchia-Rispoli, 1917, is described from the upper Cenomanian (Upper Cretaceous) Picofrentes Formation, of the Iberian Inner Castilian Platform in Guadalajara Province (Spain). Distefania buerai nov. sp. represents the third formal record of fossil decapod crustacean, and the second record for brachyuran decapods in the Cenomanian of Iberia. The paucity of crustacean remains, which contrast with the rich invertebrate faunas known in the extensive Cenomanian basins of Iberia, it may be due to the lack of favorable environments for the establishment of decapod communities in the inner Castilian Platform.
  • 天野 和孝, 稲田 陽, 佐藤 時幸
    2024 年 51 巻 1 号 p. 15-37
    発行日: 2024/05/17
    公開日: 2024/05/17
    研究報告書・技術報告書 オープンアクセス
    From the Middle to Upper Pleistocene deposits on the seabed at upper bathyal depth in the southwestern part of Japan Sea, five species of Macoma (Macoma) were recovered with some cold-water species; Macoma (Macoma) lipara Dall, 1916a, M. (M.) scarlatoi Kafanov and Lutaenko, 1997, M. (M.) golikovi Scarlato and Kafanov, 1988, M. (M.) lama meridionalis Scarlato, 1981 and M. (M.) moesta (Deshayes, 1855). All species are living in Primorye, Hokkaido and northwards. It has been elucidated that one of the characteristic species of the Omma-Manganji fauna, M. praetexta oinomikadoi Otuka, 1939 is a junior synonym of M. (M.) lipara Dall, 1919 living in Primorye via Bering Sea to California. This Macoma-dominated assemblage was deposited in the glacial stage, MIS 6 (~185–135 ka) and similar to that of the Lower Pleistocene Hamada Formation in Aomori Prefecture.
  • 加藤 進, 平松 力, 小村 健太郎
    2024 年 51 巻 1 号 p. 39-48
    発行日: 2024/08/23
    公開日: 2024/08/23
    研究報告書・技術報告書 オープンアクセス
    The Miocene sequence in the Hidaka observation well is lithologically divided into A and B formations in ascending order, whose boundary may be unconformable, and the latter is subdivided into B1, B2, B3 and B4 formations. Diatom fossils and calcareous nannofossils indicate that the A formation, which is Middle Miocene in age, is correlated to the Hiki Group in the Iwadono Hills. On the other hand, the B formation, whose age is late Middle Miocene to Late Miocene, is correlated to the Tokigawa Group. The “Kazusa Group” overlies unconformably thick Miocene sequences whose geologic ages are slightly different beneath the western part of the Kanto Plain.
  • James R. Thomka, Lilian K. Gunderson, Drew A. Billups, Thomas E. Bante ...
    2024 年 51 巻 1 号 p. 49-54
    発行日: 2024/08/23
    公開日: 2024/08/23
    研究報告書・技術報告書 オープンアクセス
    A recent article described an orthoceratid cephalopod from the Silurian of eastern midcontinental USA that is encrusted by two blastozoan echinoderms, with one attachment structure preferentially encrusting the attachment structure of the other. Discussion of the palaeoecological significance of this specimen centered around interactions between encrusting echinoderms, but as a note of secondary significance, it was reported that this occurrence supposedly represented the first published example of diploporitan encrustation of a cephalopod substratum that was not completely overgrown by the aboral region of the echinoderm. This claim is inaccurate, however, as two previously published examples have been documented. Nevertheless, the specimen represents the first published Silurian example of such a phenomenon, as both previously published examples were from other Palaeozoic systems. An additional Silurian cephalopod specimen (Dawsonoceras annulatum) displaying encrustation by a diploporitan echinoderm—the second example documented from Silurian strata—seemingly indicates that this relationship is less rare than the paucity of currently published descriptions suggests.
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