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Volume 1994 (1994)
- Issue 176 Pages 591-
- Issue 175 Pages 497-
- Issue 174 Pages 411-
- Issue 173 Pages 329-
Volume 1994, Issue 173
Displaying 1-6 of 6 articles from this issue
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YUKIO YANAGISAWA1994 Volume 1994 Issue 173 Pages 329-342
Published: April 30, 1994
Released on J-STAGE: May 25, 2010
JOURNAL FREE ACCESSMorphologic and stratigraphic study of the Miocene fossil diatom genera Katahiraia Komura and Yoshidaia Komura reveals that they are the initial valves of the genus Denticulopsis Simonsen. They have almost the same morphology and stratigraphic range as the corresponding vegetative valves of Denticulopsis, but differ in having a rounded valve shape in cross section and a central raphe. Probable vegetative Denticulopsis species are suggested for each of Katahiraia and Yoshidaia species on the basis of morphology and stratigraphic ranges.View full abstractDownload PDF (2371K) -
TOSHIMASA TANAI, KAZUHIKO UEMURA1994 Volume 1994 Issue 173 Pages 343-365
Published: April 30, 1994
Released on J-STAGE: May 25, 2010
JOURNAL FREE ACCESSThe reinvestigation of floristic components together with recent radiometric dating of the fossil-bearing deposits reveals that the "Miocene" floras including lobed oaks in East Asia (Japan, North Korea and Primorye) are Oligocene in age. These Oligocene floras consist mainly of temperate deciduous broad-leaved trees and conifers; they are characterized by commonly containing lobed and serrate/dentate oak leaves. Four fossil species of lobed oaks are confirmed from the Oligocene of East Asia : Quercus kobatakei Tanai and Yokoyama, Q. kodairae Huzioka, Q. sichotensis Ablaev and Gorovoi and Q. ussuriensis Kryshtofovich, all of which belong to the subgenus Quercus. Quercus ussuriensis belongs to the section Cerris, and is more closely similar to extant European or West Asian species than to those of East Asia. The remaining three species belong to the sections Prinus or Quercus, and they are similar to some extant species of North American Prinus or European/West Asian Quercus. A brief survey of the fossil lobed oak record in the Northern Hemisphere suggests that the phylad of Cerris originated in East Asia and eastern Kazakhstan during the Oligocene, and that it dispersed to West Asia and Europe, but never to the New World. Tertiary phytogeographic history of the sections Prinus and Quercus is conjectural, because these two sections are now difficult to distinguish only by leaf characters.View full abstractDownload PDF (4736K) -
TOSHIO KOIKE1994 Volume 1994 Issue 173 Pages 366-383
Published: April 30, 1994
Released on J-STAGE: May 25, 2010
JOURNAL FREE ACCESSA Triassic conodont Ellisonia dinodoides (Tatge) from pelagic carbonate rocks of the Taho Limestone in Ehime Prefecture, Southwest Japan is reconstructed as a quadrimembrate apparatus with the M, Sa, Sb and Sc elements. The elements represent well marked evolutionary trends in the length of the processes during the Smithian to Norian. The anterior or anterolateral and posterior processes of the elements decrease in total length from the Smithian to Anisian but seem to keep the size distribution constantly until the Norian. The inferred ratio of the M, Sa, Sb, and Sc elements is 2 : 1 : 2 : 6 in the Smithian to Anisian. The Sa element, however, is very rare or absent in the Norian. The correlation coefficient between the number of the denticles on the processes and the size of the processes varies from 0.09 to 0.75 and does not represent any evolutionary trends during the Triassic. The decrease in size of the processses during the Triassic seems a common phenomenon in long-ranged ramiform conodonts.View full abstractDownload PDF (2220K) -
KAZUSHIGE TANABE, NEIL H. LANDMAN, ROYAL H. MAPES1994 Volume 1994 Issue 173 Pages 384-400
Published: April 30, 1994
Released on J-STAGE: May 25, 2010
JOURNAL FREE ACCESSMicrostructural characteristics of the early shell portion in 41 species of Late Paleozoic Goniatitina and Prolecanitina (Ammonoidea) are described based on optical and scanning electron microscopy of well-preserved specimens from the midcontinent of North America, England, and Urals (Russia). The results of observations reveal that the two suborders exhibit certain distinct features in the embryonic shell characters that help distinguish them. Species of the Goniatitina have an elliptical caecum in median section and a relatively large ammonitella angle, whereas those of the Prolecanitina have a rectangular caecum and a proximally constricted initial chamber in median section. Furthermore, in the species of the Goniatitina, the second septum is either close to or attached to the proseptum on the dorsal side, forming a necklike structure, and the embryonic shells are sculptured by longitudinal lirae instead of the microtubercles that are present in the Mesozoic Ammonitida. These observations and the available data on Mesozoic taxa suggest that the external and internal features of embryonic shells are useful for higher-level systematics of the Ammonoidea.View full abstractDownload PDF (4682K) -
KIMIYOSHI SADA, WILBERT R. DANNER1994 Volume 1994 Issue 173 Pages 401-404
Published: April 30, 1994
Released on J-STAGE: May 25, 2010
JOURNAL FREE ACCESSDownload PDF (767K) -
KATSUMI UENO1994 Volume 1994 Issue 173 Pages 405
Published: April 30, 1994
Released on J-STAGE: May 25, 2010
JOURNAL FREE ACCESSDownload PDF (230K)
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