化石研究会会誌
Online ISSN : 2759-159X
Print ISSN : 0387-1924
45 巻, 2 号
選択された号の論文の6件中1~6を表示しています
特集「北海道から生物進化の謎を解く-日本を往来した動物たちの軌跡-」
巻頭言
特集・講演録
  • 犬塚 則久
    原稿種別: 特集・講演録
    2013 年 45 巻 2 号 p. 31-43
    発行日: 2013年
    公開日: 2025/01/23
    ジャーナル フリー

     Paleoecological studies about two genera, Desmostylus and Paleoparadoxia, representative of the order Desmostylia have increased in number in recent years. To background the audience, the presenter informs about osteological differences between both genera and morphological data which resulted in ecological restoration. Moreover, recent studies by other authors with some comments are introduced.

  • 高橋 啓一, 添田 雄二, 出穂 雅実, 小田 寛貴, 大石 徹
    原稿種別: 特集・講演録
    2013 年 45 巻 2 号 p. 44-54
    発行日: 2013年
    公開日: 2025/01/23
    ジャーナル フリー

     In this article, we describe the research history and recent studies on elephant fossils from Hokkaido and present five new results of AMS 14C dating. Recently, the dates of many Naumann’s elephants, Palaeoloxodon naumanni, and mammoths, Mammthus primigenius, from Hokkaido were clarified by AMS 14C dating, and enabling discussions on the relationship of global climatic changes and the north-south migrations of the two fossil elephant species.

     Examination of previous AMS 14C dates, together with the five new dates presented herein, reviel that the range of Naumann’s elephants and, that of mammoths overlapped at around 34,000-35,000 cal BP and at 45,000 cal BP. However, it is known that these two kinds of elephant inhabited different environments, as shown by pollen analyses and plant macrofossils at some localities. The apparent overlapping ranges of the two kinds of elephant during these periods is a result of measurement errors, and it shows that it is difficult to mark their precise location on a graph of global climate change. We should not trust only results of AMS 14C dating, but must also consider the relationship between elephants and habitat in a comprehensive way by including paleoenvironment of data.

  • 古沢 仁
    原稿種別: 特集・講演録
    2013 年 45 巻 2 号 p. 55-60
    発行日: 2013年
    公開日: 2025/01/23
    ジャーナル フリー

     According to the analysis of paleo-sea levels by Haq et al. (1988), Late Miocene (10.5 Ma) levels were extremely low. If low sea levels indicate extremely severe climate, then species of Dusisiren on both sides of the North Pacific survived under the extremely cool conditions. It is assumed that the loss of functional teeth and enlargement of body size took place after severe climatic cooling. These dramatic changes in the hydrodamalines suggest the possibility that environmental changes influenced marine vegetation. The Hydrodamalinae changed the type of food and their way and amount of feeding. These changes were directly connected to the enlargement of body size and loss of functional teeth.

原著
  • Chiyomi YAMAKAWA, Shogo KONISHI
    原稿種別: Original report
    2013 年 45 巻 2 号 p. 61-69
    発行日: 2013年
    公開日: 2025/01/23
    ジャーナル フリー

     Fossil fern fronds of three taxa occur in the early Pleistocene Kobiwako Group in Minakuchi, Shiga Prefecture, central Japan. All fern fossils are impressions of sterile fronds, and they are described in terms of their morphological features: division of blades, forms of pinna and pinnule, and types of venation. The three taxa identified are Thelypteris cf. T. palustris (Salisb.) Schott, Onoclea cf. O. sensibilis L. var. interrupta Maximowiczi, and Polypodiales, and these ferns constitute important specimens among the sparse records of early Pleistocene fossil ferns in Japan.

     Fossil fern fronds were preserved in their growing position by a volcanic ash fall and were found in a tuffaceous peaty-silt bed just below the base part of the Hazama ash layer (c.a. 2.3 Ma), occurring together with Aristolochia, Acer, and Ilex, as well as fossil leaves of Cyperaceae. The ferns were growing in an open back-marsh or swamp habitat around a forested area.

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