化石研究会会誌
Online ISSN : 2759-159X
Print ISSN : 0387-1924
45 巻, 1 号
選択された号の論文の3件中1~3を表示しています
原著
  • Sonia CHAVEZ, Sara ZUFAN, Sun H. KIM, Kenshu SHIMADA
    原稿種別: Original report
    2012 年 45 巻 1 号 p. 1-5
    発行日: 2012年
    公開日: 2025/01/23
    ジャーナル フリー

     The porbeagle shark, Lamna nasus (Bonnaterre), is an extant lamniform shark. We used linear regression analysis to quantitatively examine the relationships between the total body length (TL) and height of the tooth crown (CH) of each tooth in 19 Lamna nasus individuals ranging 104-244 cm TL from northern Atlantic Ocean. We obtained a total of 25 independent regression equations, and they all suggest that increase in CH of each tooth through tooth replacements is proportional to increase in TL with a high correlation coefficient between TL and CH. Our regression equations can increase the efficiency of the TL data collection from captured individuals useful for ecological monitoring. They can also be used to extrapolate the TL of fossil L. nasus from teeth that would help paleoecological inferences.

  • Takehisa TSUBAMOTO, Naoko EGI, Masanaru TAKAI, THAUNG-HTIKE, ZIN-MAU ...
    原稿種別: Original report
    2012 年 45 巻 1 号 p. 6-10
    発行日: 2012年
    公開日: 2025/01/23
    ジャーナル フリー

     The upper molar morphology of an enigmatic indeterminate artiodactyl (Mammalia), Artiodactyla indeterminate 1 (Tsubamoto et al., 2005, Acta Palaeontol. Pol. 50, 117-138), from the middle Eocene Pondaung Formation of Myanmar is described in detail and is compared with an enigmatic artiodactyl Aksyiria from the middle Eocene of Kazakhstan. This upper molar is characterized by bunodont cusps, a square occlusal outline, a hypocone, non-selenodont conules, a parastyle, and a straight ectoloph. This indeterminate artiodactyl is distinct from Aksyiria at the genus level in having a stronger parastyle, a large hypocone, non-selenodont conules without link to the cingulum, and a more mesially located protocone, and in being much larger. Although it represents a new genus and species because of its unique upper molar morphology, new taxa are not established here because of the scarcity and heavily damaged nature of the material.

講演録
  • 佐藤 たまき
    原稿種別: 講演録
    2012 年 45 巻 1 号 p. 11-13
    発行日: 2012年
    公開日: 2025/01/23
    ジャーナル フリー

     首長竜は中生代を代表する海生爬虫類であり,その化石は世界の様々な地域の三畳紀最後期から白亜紀末にかけての地層から見つかっており,非海成層からも少数ながら報告がある.ほぼ同時代に生息した恐竜とは頭骨や四肢の形状,系統学的な位置づけ,生殖形態などにおいて異なっていた.首長竜の起源は三畳紀のピストサウルス類と呼ばれる鰭竜類にあると考えられているが,様々な首長竜の系統関係については統一した見解が得られておらず,しばらくは議論が続くことが予想される.

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