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A new genus Morewites is herein erected for a Cretaceous heteromorph ammonoid from the Campanian (Upper Cretaceous) of Hokkaido, northern Japan. The new genus differs from previously described genera of the family Nostoceratidae by its minute helical initial whorls, whose axis of coiling is at right angles to that of its loosely elliptically coiled planispiral whorls.
Seven species of Gastropoda and 21 species of Bivalvia were discriminated from the Miocene Ichibu Formation on Nishinoshima Island, Oki Islands, Southwest Japan. The co-occurrence of Nipponopecten akihoensis (Saga), Chlamys (Nomurachlamys) kaneharai (Yokoyama), and Miyagipecten matsumoriensis indicates a latest middle—earliest late Miocene age (ca. 12.5–11.5 Ma) for the formation. The Ichibu molluscan fauna commonly includes eurythermal and North Pacific elements, whereas only two warm-water species were recognized. This fact shows that the shallow sea around the Oki Islands was under a temperate marine climate weakly influenced by the Paleo-Tsushima Current in latest middle—earliest late Miocene time. Taxonomically described and/or discussed species include Costanuculana godaigoi Matsubara, sp. nov. and Yabepecten okiensis Matsubara, sp. nov.
We describe one new aporrhaid species, Kangilioptera inouei sp. nov., from the Paleocene Katsuhira Formation in Urahoro Town, eastern Hokkaido, Japan. This is the first record of a Cenozoic Aporrhaidae (Anchurinae) gastropod in Japan. Occurrences of Kangilioptera are confined to Paleocene deposits in western Greenland and Japan. With the addition of the bivalve Conchocele, the new find requires a reappraisal of the marine connection through the Bering Strait between Japan and Greenland during the Paleocene.
A stalk fragment of the millericrinid crinoid Pomatocrinus sp. from the lower Kimmeridgian of Małogoszcz Quarry (Central Poland) consists of a partly preserved holdfast and a distal stalk fragment, which yields numerous epibionts and echinoid grazing traces. Importantly, the described stalk shows evidence of narrowing of the proximal part. Such a pathological structure of the apical part of the column likely represents a nonregenerative overgrowth of the stalk following the loss of the proximal column and crown due to nektonic predation as inferred from associated bite marks. Analogous pathological structures in fossil crinoids, although rare, are known from as far back as the Ordovician.
Molluscan larval shells are described from the upper Carboniferous (Moscovian) Ichinotani Formation at Fukuji, Okuhida-onsen-gou, Takayama City, Gifu Prefecture, Japan. The vast majority of these larval shells are isolated and not metamorphosed. The larvae appear to represent species with planktotrophic larval development representing pseudozygopleurid, streptacidid and indeterminate gastropods and pteriomorph and anomalodesmacean bivalves. This is the first report of isolated molluscan larval shells from Palaeozoic deposits in Japan.
An ammonoid fauna comprising eight species belonging to seven genera (Agathiceras, Neoglaphyrites, Emilites, Somoholites, Marathonites, Eoasianites and Metapronorites) is described from the Uyamano Formation (Taishaku Limestone) at Miharanoro in the Akiyoshi Belt, Southwest Japan. The fauna includes two new species: Neoglaphyrites discoidalis and Somoholites miharanoroensis. The genera Emilites, Somoholites, Marathonites, and Metapronorites are described from Japan for the first time. From the coexisting interval of these seven genera, the age of the Miharanoro fauna is between the Kasimovian and Asselian, being very probably Asselian because some species show close resemblance to those known from Asselian strata. This is the most diverse early Permian ammonoid fauna ever known from Japan.