Paleontological Research
Volume 16, Issue 4, 2013
Volumes & issues:
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Spatial Distribution of Recent Ostracode Assemblages and Depositional Environments in Jakarta Bay, Indonesia, with Relation to Environmental Factors
View Description Hide DescriptionAbstract.Jakarta Bay is a semi-enclosed bay, located on the western side of the northern part of Java Island, Indonesia. This study reports the spatial distribution of recent ostracode assemblages from the top of 19 core samples collected in 1994 and the relationship between the assemblages and environmental factors. This study is the first of the ostracode species of Jakarta Bay, and succeeded in identifying 94 species living there. Ostracodes are common in the East Indian Province. The dominant species found were Keijella carriei Dewi, Hemicytheridea reticulata Kingma, Loxoconcha wrighti Dewi, and Hemicytheridea ornata Mostafawi. Species belonging to the genera Cytherella, Cytherelloidea, Neomonoceratina, and Pistocythereis were also abundant. According to Q-mode cluster analysis, three biofacies (I, II, and III) were recognized, clearly distributed from the inner to the outer parts of the bay. Biofacies I is distributed in the muddy bottoms of the inner to the middle parts of the bay and is composed mainly of K. carriei, L. wrighti, and H. reticulata. Biofacies II is distributed in the muddy bottoms of the outer part of the bay and is characterized by the abundance of H. reticulata, H. ornata, and Cytherella spp. Biofacies III is distributed in the sandy mud bottoms of the outer part of the bay, and is characterized by high-diversity assemblages composed of Atjehella kingmai Keij, Foveoleberis cypraeoides (Brady), Neomonoceratina bataviana (Brady), and Pistocythereis cribriformis (Brady). This study correlated relationships between dominant species and bottom environment factors such as total organic carbon (TOC), total sulfur (TS), total nitrogen (TN), total organic carbon/ total nitrogen ratio (C/N ratio), and total organic carbon/total sulfur ratio (C/S ratio). The results show that K. carriei and L. wrighti are common in areas with high TOC and TN contents, even when they are anoxic, while H. ornata and H. reticulata preferably thrive in deeper areas with low TOC and TN contents. Thus, because of these environmental factors, species diversity and density are low in near-shore sites where the TOC content of mud is relatively high and the bottom is anoxic or oxygen-poor even though the water is shallow.
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Early Carboniferous Ammonoid Dombarites from the Taishaku Limestone, Akiyoshi Belt, Southwest Japan
View Description Hide DescriptionAbstract.The Early Carboniferous ammonoid Dombarites taishakuensis sp. nov. is described from the Dangyokei Formation, which is the lowermost formation of the Taishaku Limestone in the Akiyoshi Belt, Southwest Japan. This is the first described ammonoid from the Taishaku Limestone and the first record of the genus Dombarites from the Panthalassa region. The age of D. taishakuensis is probably early Serpukhovian based on the ages of morphologically similar species of Dombarites.
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Middle Permian Ostracods from the Akasaka Limestone, Gifu Prefecture, Central Japan
View Description Hide DescriptionAbstract.Samples of Middle Permian organic-rich black unconsolidated mud were collected from a fissure of black limestone in Kinshozan Mountain, Akasaka City, Gifu Prefecture, central Japan. Nine new species, one new genus and one new family are described herein: Ikeyaparchitidae Tanaka fam. nov., Gifuaparchites Tanaka and Maeda gen. nov., Aurikirkbya kinshozanensis Tanaka sp. nov., Gifuaparchites takagii Tanaka and Maeda sp. nov., Cavellina hashintotoi Tanaka and Maeda sp. nov., Bairdia nishiwakii Tanaka and Nishimura sp. nov., Bairdia akasakaensis Tanaka sp. nov., Bairdia oogakiensis Tanaka sp. nov., Bairdiacypris? hayasakai Tanaka sp. nov., Acratia? okumurai Tanaka sp. nov., and Acratia? hamadai Tanaka, Ono and Maeda sp. nov. This is the first report from Japan of a typical Panthalassa ostracod assemblage during the Middle Permian, and of which is characterized by typically endemic species.
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Suids from the Pleistocene of Naungkwe Taung, Kayin State, Myanmar
View Description Hide DescriptionAbstract.The aim of this paper is to put on record an occurrence of fossiliferous spelean sediments at Naungkwe Taung, Myanmar, not far from the mouth of the Salween River where it debouches into the Martaban Gulf, Andaman Sea. The fauna from the deposits includes a diversity of mammals (suids, cervids, bovids, ursid carnivores) among which there is an extinct suid of diminutive dimensions related to the Pygmy Hog (Porcula salvania) and a larger species close in size to the extant Warty Pigs (Dasychoerus verrucosus). The small suid is morphometrically close to the species “Sus” sangiranensis from Sangiran, Java, and “Sus” xiaozhu from Bijiashan, China, and slightly larger than extant Porcula salvania. The fossiliferous deposits at Naungkwe Taung, Kayin State, Myanmar, correlate best to Bijiashan Cave, China, to the younger part of the Liucheng Cave succession, China, and part of the sequence at Sangiran, Java. A Middle Pleistocene age is suggested.
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A New Miocene Three-Spined Stickleback (Pisces: Gasterosteidae) from Central Japan
View Description Hide DescriptionAbstract.Gasterosteus kamoensis sp. nov. is described from the Upper Miocene Minamiimogawa Formation in Kamo City, Niigata, Japan. The new species represents the oceanic complete morph. It is characterized by: short and high ectocoracoid; presence of posttemporal bone; fully developed pelvic girdle with convex anterior margin; wide and not tapering posterior process of pelvic bone; four dorsal spines; comparatively long spines in dorsal, pelvic and anal fins; and large body size, apparently exceeding 130 mm in standard length. Gasterosteus kamoensis sp. nov. is the third nominal fossil species of this genus described from East Asia, along with freshwater G. orientalis Sytchevskaya and the marine G. abnormis Gretchina. Together, these discoveries demonstrate the wide distribution and morphological and ecological diversity of this genus during the Miocene in the northwestern Pacific.
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SHORT NOTE