1 0 0 0 OA 美濃帯犬山地域のジュラ紀中世(Bajocian)放散虫類の群集変遷
- 著者
- 西原 ちさと 八尾 昭
- 出版者
- 日本古生物学会
- 雑誌
- 化石 (ISSN:00229202)
- 巻号頁・発行日
- vol.78, pp.32-39, 2005-09-28 (Released:2017-10-03)
This paper reports on a faunal change of Middle Jurassic (Bajocian) radiolarians from manganese carbonate nodules in the Inuyama area, Mino Terrane. Five radiolarian assemblages, distinguished from five horizons (IN-16, IN-10, IN-7, IN-3 and IN-1 in ascending order) of the Unuma section, are well-preserved and extremely diversified in specific composition. About 300 species of radiolarian fossils are obtained from each manganese carbonate nodule. Approximately two thirds of radiolarian species are composed of common species between two horizons. The value of Spumellaria/Nassellaria (S/N) ratio is high in the lowermost horizon (IN-16) and low in the uppermost horizon (IN-1). Although the extinction and origination rates of radiolarian species are totally constant through the section, the origination of nassellarian species in the uppermost horizon shows a high rate. On the basis of these faunal analyses, the radiolarian faunal change was constant during Bajocian time except for a little change of the S/N ratio and the origination rate of nassellarian species. It is suggested that there was not the large oceanic environmental change during Bajocian time in the western part of the Panthalassa.
- 著者
- 高橋 雅紀 安藤 寿男
- 出版者
- 日本古生物学会
- 雑誌
- 化石 (ISSN:00229202)
- 巻号頁・発行日
- no.100, pp.45-59, 2016-09
1 0 0 0 亀井節夫先生のご逝去を悼む
- 著者
- 神谷 英利
- 出版者
- 日本古生物学会
- 雑誌
- 化石 (ISSN:00229202)
- 巻号頁・発行日
- vol.97, pp.39-41, 2015
1 0 0 0 OA カキの古生態学 (1)
- 著者
- 鎮西 清高
- 出版者
- 日本古生物学会
- 雑誌
- 化石 (ISSN:00229202)
- 巻号頁・発行日
- no.31, pp.27-34, 1982-06-21
- 被引用文献数
- 4
Some paleoecologic aspects of oysters are discussed, giving special emphasis on the adaptive strategy of Crassostrea to the soft muddy bottom. Crassostrea is most abundant in the muddy intertidal facies despite their sessile and suspension feeding habit. Muddy bottom environment seems unfavorable for oysters because it offers very few basis of attachment, and gives continuous danger of suffocation by rapidly accumulating mud. Crassostrea surmounts these difficulties in living on mud, and becomes dominant in this environment. The basic strategy of Crassostrea for the survival in the muddy bottom is considered to be their gregarious tendency to constitute the densely aggregated colony. The colony supports the individual shell to stand above the surface of mud, and gives the firm basis for the attachment of later generations. The later generations grow on the colony, thus manage to keep living animals atop the rising mud level. Formation of the biohermal reef is the consequence of this characteristic behavior of Crassostrea. Nongenetic variations in shell morphology are conspicuous among Crassostrea individuals. The shell outline of fossil and living Crassostrea gigas is not controlled by the population density, but is probably related to the position of the shell : individuals in the upright position tend to be elongated irrespective of their density, and those lying on the bottom are usually more rounded. The population density apparently affects the individual shell size. Where the density is low, shells are very large, while they are small in densely populated reefs. The relationship may be explained by the competitive effect in the allocation of limited food supply.
1 0 0 0 OA メタセコイア属の古生態と古生物地理(生きている化石)
- 著者
- 百原 新
- 出版者
- 日本古生物学会
- 雑誌
- 化石 (ISSN:00229202)
- 巻号頁・発行日
- no.57, pp.24-30, 1994-11-30
- 被引用文献数
- 1
The fossil Metasequoia, Taxodiaceae, occurs in the upper Cretaceous and Tertiary of Northern Hemisphere. The Paleogene records are widely distributed in mid to high latitudes (N 40°-80°) except for eastern America and Europe. In the late Miocene, they were restricted to the area including Alaska, Kamchatka, and eastern Asia. The Pliocene and Early Pleistocene records are known only from Japan. The occurrence of fossil assemblages shows that Metasequoia constructed swamp forest in fluvial plains. The extant wild habitat of Metasequoia glyptostroboides restricted in the wet places in the valley bottom and backmarsh of the river. The fast growth and photophilous habit of the seedlings indicate Metasequoia is a pioneer plant.
1 0 0 0 ワニの筋学-古脊椎動物学者に必要な解剖- : II.肩帯・前肢
To understand the inter- and intraspecies variation and ontogenetic change in shell ornamentation of Polyptychoceras (Cretaceous diplomoceratid), reproduction of shell morphologies was carried out based on the creeping soft-part model and the lazy messenger effect. As a result, we found several constructional rules on this ammonite as follows. (1) The shell surface of Polyptychoceras consists of "striation-" and "smooth-parts", and the former was much more slowly formed than the latter. (2) The changes in shell ornamentation during growth of Polyptychoceras (Polyptychoceras) haradanum were probably caused by change in shell prolongation rate, and were successfully restored if the striation- and smooth-parts were assumed to be formed through gradual expansion and intermittent forward movement of the soft-part, respectively. (3) The formation of the multiple ribs observed in Polyptychoceras (Subptychoceras) yubarense can be attributed to a refractory period for propagation of the morphogenetic signals just after the formation of the continuous smooth-part including ribs. Our conclusion is that the great variability of shell ornamentation developed in Polyptychoceras is the result of compound effect of two factors, i.e. the rate of shell prolongation and the duration of the refractory period for ribbing.
1 0 0 0 OA 下部白亜系宮古層群のストーム卓越型浅海成シーケンスにおける軟体動物化石層
- 著者
- 北村 晃寿
- 出版者
- 日本古生物学会
- 雑誌
- 化石 (ISSN:00229202)
- 巻号頁・発行日
- no.88, pp.59-60, 2010-09-30
1 0 0 0 OA 第5回国際三葉虫学会TRILO2012参加報告(学術集会参加報告)
- 著者
- 椎野 勇太 鈴木 雄太郎
- 出版者
- 日本古生物学会
- 雑誌
- 化石 (ISSN:00229202)
- 巻号頁・発行日
- no.92, pp.40-42, 2012-09-28
1 0 0 0 OA 気候変動の現在,過去そして近未来地球温暖化問題を考える, 秋山雅彦(著), 地学団体研究会, 2012年5月19日, 96pp, ISSN0918-5372, 1,000円(税込), 送料180円
- 著者
- 後藤 仁敏
- 出版者
- 日本古生物学会
- 雑誌
- 化石 (ISSN:00229202)
- 巻号頁・発行日
- no.92, pp.38-40, 2012-09-28
- 著者
- 上田 庸平 ジェンキンズ ロバート G 安藤 寿男 横山 芳春
- 出版者
- 日本古生物学会
- 雑誌
- 化石 (ISSN:00229202)
- 巻号頁・発行日
- vol.78, pp.47-58, 2005
- 参考文献数
- 26
- 被引用文献数
- 3
Various-sized and -shaped calcareous concretions occur abundantly in the Lower Miocene Kokozura Formation of the Takaku Group which crops out on the Izura coast and its nearby north, Kita-Ibaraki City, north of Ibaraki Prefecture. The Kokozura Formation is mainly composed of intensely bioturbated, very fine-grained muddy sandstone, which may have been deposited on the outer shelf of the Joban forearc basin. The calcareous concretions are divided into the following six types on the basis of their shapes, sizes and modes of occurrence : Type I (large-sized concretions with undulatory surface, 1 to 6m in diameter), Type II (smaller, less than a few decimeters in diameter, and irregular-shaped concretions closely associated with Type I), Type III (pipe-shaped hollow concretions, a few decimeters in diameter and less than 2m in length), Type IV (sheet to lenticular concretions, 10 to 20cm in thickness and a few meters in lateral length), Type V (burrow-fill sand concretions concentrated and connected to each other in very fine-grained sandstone) which grades upward into Type VI (concreted sandstone bed, 2 to 3m in thickness, including abundant burrows). In the lower part of the outcrop, the Types I and II are dominant and commonly associated with Type III, whereas the uppermost part consists of Types V and VI which developed into a huge concreted bed, 2 to 3m thick, over 50m wide and 100m long. ^<13>C-depleted carbon isotopic compositions (-20.9 to -29.2‰ vs PDB) of Types I and II suggests that these concretions were formed under the influence of methane seepage. Molluscan assemblages dominated by Lucinoma acutilineatum are associated with the Type I, II, and III concretions. Most of L. acutileatum shells keep their life position. The mode of fossil occurrence indicates that L. acutileatum formed a chemosynthetic community and used methane seepage through chemosynthetic bacteria for their energy source.
1 0 0 0 OA 北海道,忠類産ナウマンゾウの再検討
The Churui specimen was found in 1969 and 1970 from Bansei, Churui, Makubetus-cho, Nakagawa-gun, Hokkaido, and is one of the most important whole skeletons of Palaeoloxodon naumanni. Herein, we reexamine the molar number and specific identification of this specimen. As a result of our observations, four molars that were previously identified as second molars of one individual are re-identified as third molars of one individual. These molars correspond to the group 25-27 of Laws (1966), and are therefore assumed to represent an age of about 50 years. Observations of the epiphyseal fusion of the postcranial bones in the Churui specimen support the result that the animal used its third molars. A molar that was previously identified as a third molar from the same individual as the four "second molars" of P. naummmni, is re-identified as a second or third molar of the woolly mammoth Mammuthus primigenius, as determined by morphological characters. It gave a radiocarbon date of 42,850+510BP. Woolly mammoths inhabited Hokkaido from 45ka to 16ka, while the horizon of P. naumanni from Churui is estimated to be 120ka. This suggests that the molar of the woolly mammoth fell from the upper part of the cliff at the excavation site of the Churui specimen, instead of being recovered from the excavation plane.
1 0 0 0 OA 古琵琶湖層群から産出した鳥類足跡化石
- 著者
- 岡村 喜明 高橋 啓一 琵琶湖博物館資料調査協力員
- 出版者
- 日本古生物学会
- 雑誌
- 化石 (ISSN:00229202)
- 巻号頁・発行日
- no.55, pp.9-15, 1993-11-30
Fossil footprints of a bird referable to the suborder Gruidea were found from the Pliocene Kobiwako formation of Mie Prefecture, central Japan. The footprints are relatively large and show four toes. Toes II to IV direct forwards with a wide splay angles, while toe I points backwards at a low position. Each toe is wide and with a claw impression at the tip. Metatarsal impression is preserved on the sole. A small area of webbing is present between III and IV only. The stride is 320〜500mm. This record provides additional information about the fauna of the Pliocene Kobiwako formation.
- 著者
- 高橋 啓一
- 出版者
- 日本古生物学会
- 雑誌
- 化石 (ISSN:00229202)
- 巻号頁・発行日
- no.56, 1994-06-30
- 著者
- 高橋 啓一
- 出版者
- 日本古生物学会
- 雑誌
- 化石 (ISSN:00229202)
- 巻号頁・発行日
- no.70, 2001-09-21
1 0 0 0 OA 香川県高松市塩江町の上部白亜系和泉層群より産出したオサガメ科化石
A partial skeleton of Mesodermochelys undulatus Hirayama and Chitoku, 1996 (Testudines: Chelonioidea: Dermochelyidae), with carapace estimated as 1.3m long, was collected from the Late Cretaceous (early Late Campanian) Izumi Group at Shionoe, Takamatsu City, Kagawa Prefecture, Western Japan. This occurrence supports the presence of highly localized sea turtle fauna dominated by Mesodermochelys in the sea adjacent to Japan during the Late Cretaceous.
- 著者
- 間嶋 隆一
- 出版者
- 日本古生物学会
- 雑誌
- 化石 (ISSN:00229202)
- 巻号頁・発行日
- no.44, pp.13-23, 1988-06-03
- 被引用文献数
- 1
Japanese Glossaulax ranges in age from the Middle Miocene to Recent, and consists of the following seven species : G. didyma (Roding), early Middle Miocene-Recent; G. vesicalis (Philippi), Early Pleistocene-Recent; G. hyugensis (Shuto), Early Pliocene-Late Pliocene; G. hagenoshitensis (Shuto), Late Pliocene-Early Pleistocene; G. nodai Majima, Late Pliocene-Early Pleistocene; G. bicolor (Philippi), Late Miocene-Recent; and G. reiniana (Dunker), Late Pliocene-Recent. Among them, the evolution of G. hyugensis, G. hagenoshitensis and G. nodai is discussed in part II of the present study. Glossaulax didyma is considered to be a descendant of a Glossaulax species in northwestern America where Glossaulax ranges in age from the Eocene to Recent. In Pliocene time, G. didyma gradually changed its morphology and increased its morphological variability. Glossaulax vesicalis evolved from G. didyma. In Late Pliocene time, G. didyma had a local population that showed an extremely wide range of morphological variation, including one variant very similar to the earliest known individuals of G. vesicalis. This population appears to be a transitional population between G. didyma and G. vesicalis. Glossaulax bicolor and G. reiniana are considered to be descendants of G. didyma. They share some important characters with G. didyma.
- 著者
- 間嶋 隆一
- 出版者
- 日本古生物学会
- 雑誌
- 化石 (ISSN:00229202)
- 巻号頁・発行日
- no.45, pp.1-7, 1988-12-15
(1) Glossaulax hyugensisは後期中新世ないし前期鮮新世にG. didymaから進化した.この種分化の際, G. hyugensisの個々の個体に生じた個体発生上の異なりが遺伝的に固定された.(2)後期鮮新世にGlossaulax hagenoshitensisはG. hyugensisからperamorphosisにより, またG. nodaiはG. hyugensisからpaedomorphosisにより進化した.これらの進化はheterochronyの特殊な様式によって説明される.3種は前期更新世までにいずれも絶滅した.
