Paleontological Research
Volume 14, Issue 4, 2010
Volumes & issues:
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Reevaluation of the Late Carboniferous Cephalopod, Brachycycloceras? Spectrum Hansman, 1965 from Texas, USA
View Description Hide DescriptionAbstract.New material of the Virgilian (Upper Carboniferous) nautiloid cephalopod Brachycycloceras? spectrum Hansman, 1965, from the Necessity Shale and the Finis Shale (the type stratum of this species) members of the Graham Formation in Texas, has prompted a reevaluation of this insufficiently described species. On the basis of morphologic differences between the present material and Brachycycloceras normale Miller, Dunbar and Condra, 1933, the type species of the genus, the species is transferred from its previous placement with reservation to the orthoceratid genus Cryptocycloceras Shimansky, 1968 as C. spectrum (Hansman, 1965). Specimens of Cryptocycloceras have been recovered from Russia, and an older, related genus Hidamichelinoceras Niko, 2000 has been recovered in Japan.
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Terrestrial and Freshwater Pulmonate Gastropods from the Early Cretaceous Kuwajima Formation, Tetori Group, Japan
View Description Hide DescriptionAbstract.Five species of pulmonate gastropods are described from the fluvial deposits of the Early Cretaceous Kuwajima Formation (Tetori Group) of Shiramine district, Hakusan City, Ishikawa Prefecture, central Japan. Gyraulus sp., Aplexa kasekikabe sp. nov. and Zaptychius kuwajimaensis sp. nov. appear to be inhabitants of the marginal zone in shallow lakes. Pseudarinia wangyingensis and Tetoripupa costata gen. et sp. nov. are land snails that probably inhabited vegetated swamps located near shallow lakes. T. costata is the earliest record of the stylommatophoran pulmonate clade Pupilloidea. This fauna contains a common and closely related species to the Jehol molluscan fauna from the Early Cretaceous of northern China, and also appears to be utilizable for paleoenvironmental analysis of terrestrial to freshwater microhabitats.
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Discovery of the Middle Triassic Ammonoid Balatonites in the Quy Lang Formation, Thanh Hoa Province, Central Vietnam
View Description Hide DescriptionAbstract.The discovery of Balatonites sp. in the lower part of the Quy Lang Formation in the Lang Nuoc area, Thanh Hoa Province, Central Vietnam establishes that this portion of the formation is of late Middle Anisian age. This ammonoid's cooccurrence with Costatoria goldfussi mansuyi and Trigonodus tonkinensis suggests that this widely distributed bivalve assemblage in Asian shallow marine facies is at least partly of late Middle Anisian age, and its discovery may provide an important key for the establishment of a precise biostratigraphic framework for the Middle Triassic of Asia.
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Variation in a Population of Theropoda (Dinosauria): Allosaurus from the Cleveland-Lloyd Quarry (Upper Jurassic), Utah, USA
View Description Hide DescriptionAbstract.Ontogenetic and individual variation in a population of the large theropod Allosaurus cf. A. fragilis was examined using the Björk superimposition method on the premaxillae, maxillae, lachrymal, postorbital, and jugal. This method allows utilization of incomplete specimens without having to estimate (fabricate) missing data. In addition, it visually shows regions of ontogenetic change and variation. Comparison of these results with other morphometric studies of the same specimens show that most allometric trends are not supported. Instead, ontogenetic change is mostly isometric. In addition, the wide range of individual variation in all the skull elements analyzed makes some autapomorphic characters used to define other theropod taxa suspect.
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Late Middle Permian (Capitanian) Foraminifers from the Uppermost Part of the Taishaku Limestone, Akiyoshi Terrane, Japan
View Description Hide DescriptionAbstract.Forty-four species assignable to 32 genera of late Middle Permian (Capitanian) foraminifers are distinguished from Lepidolina limestone and microbial limestone of the uppermost part of the Taishaku Limestone, northeastern part of Hiroshima Prefecture, Japan. The microbial limestone contains Kahlerina taishakuensis sp. nov. enclosing problematic microfossils within their tests and is taxonomically less diversified than the Lepidolina limestone. Faunal composition of nonfusuline foraminifers is clarified in the Lepidolina Zone of the Akiyoshi Terrane for the first time. In addition to the new species, seven species are systematically described. They are Codonofusiella sp. cf. C. ashioensis Kobayashi, Chusenella otai (Nogami), Parafusulina sp., Lepidolina multiseptata (Deprat), Hemigordiopsis renzi Reichel, Baisalina ovata Han, and Partisania typica Sosnina. Taxonomic comments are given on Kahlerina and Hemigordiopsis.
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Ikiculter chojabaruensis, a New Genus and Species of Cyprinid Fish from the Miocene of Iki Island, Nagasaki, Japan
View Description Hide DescriptionAbstract.Ikiculter chojabaruensis is described on the basis of three specimens from the Miocene of Iki Island, Nagasaki, Japan, as a new genus and species of the family Cyprinidae. This new species possesses an elongate body, modified first unbranched fin ray of dorsal fin, extremely stout third dorsal spinelike fin ray with smooth posterior edge, apart tips of deeply forked basipterygium with a dorsal wing, elongated pterotic, smooth surface of opercle, large third vertebra twice as large as second one, 13 branched anal fin rays and 21 abdominal and 20 caudal vertebrae. A phylogenetic study using the character matrix of a previous study suggests that the species is related to leuciscins+phoxinins, Ecocarpia, Iquius, xenocyprinins and cultins and is probably a sister taxon to a clade of Iquius+xenocyprinins and cultrins. An extinct group closely related to Recent cultrins and xenocyprinins existed in Miocene East Asia.
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Panthalassan Seamount-Associated Permian-Triassic Boundary Siliceous Rocks, Mino Terrane, Central Japan
View Description Hide DescriptionAbstract.We describe the lithology and age of an intact section (NF 1212R) and two reference sections of Panthalassan seamount-associated Permian-Triassic boundary (PTB) siliceous rocks. The sections occupy the upper part of the Hashikadani Formation of the Mino terrane in the Mt. Funabuseyama area, central Japan. Section NF 1212R comprises a lower unit of gray chert (ca. 1.7 m thick), a middle unit of dark gray to black chert (ca. 0.8 m) with a pyrite-rich layer at the top (ca. 0.1 m), and an upper unit of black claystone with thin, intermittent beds of black to dark gray chert (ca. 1.2 m), in ascending order. The chert of the lower and middle units is rich in radiolarian remains with minor siliceous sponge spicules. The black chert of the middle unit is carbonaceous and includes tiny pyrite grains. The black claystone consists of microcrystalline quartz and clay minerals rich in carbonaceous matter. The chert of the upper unit is also carbonaceous and rich in radiolarian remains. The lower and middle units are correlated with the Neoalbaillella optima Zone (Changhsingian). The basal part of the upper unit is referable to the Hindeodus parvus Zone (basal Griesbachian), and the major part of the upper unit is possibly correlated with the middle to upper Dienerian. We position the PTB at the sharp lithologic boundary between the upper Upper Permian chert and lower Lower Triassic black claystone. The examined PTB siliceous rocks are stratigraphically attributed to the upper part of the Hashikadani Formation, reconstructed as an oceanic rock unit characterized by Lower Permian to Lower Triassic siliceous rocks that accumulated upon the lower flank of a mid-oceanic seamount in a pelagic realm of the Panthalassa Ocean. Our results present the world's first record of deep-marine PTB siliceous rocks associated with a Panthalassan seamount.