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Diatomaceous laminites of the Pleistocene Shiobara Group (caldera fill), located in the volcanic front of the Northeastern Japan Arc, are the profundal facies of palaeo-Shiobara Lake. The laminites are subdivided into five types: clastic (Type A), diatom-preserved (Type B), porcelainised (Type C), double (Type D) and reversal (Type E). These varieties are mostly induced by lithification, due to localised hydrothermal alteration represented as the diatom frustules' transformation from opal-A to opal-CT. Type B laminite alters to Type C, Type D and finally Type E laminite in a progressive order. As alteration proceeds, the rock become more consolidated, and lamina texture changes from porous to massive. Exceptionally, Type A laminite, composed of grey terrigenous lamina, shows almost no changes, because of its poor content of diatom frustules. Type B laminite, composed of porous white diatomaceous lamina and grey terrigenous lamina, is replaced by Type C laminite, composed of tightly packed opal-CT lepispheres. Type D laminite is represented as a set of four laminae; grey, white-1, black, and white-2, in upwardsequence. The black laminae result from additional reprecipitation within the white laminae, and laterally fade. Type E laminite is the last stage of the alteration series of the laminites in Shiobara and consists of thin couplets of grey and black laminae. White laminae completely alter to black laminae. These laminite variations are likely derived from alteration by hydrothermal water associated with the caldera. Whereas Type A and B laminites are widely distributed in the basin, the distribution of Type C is restricted. Type D and E laminites are found only at one quarry which yields exceptionally well preserved megafossils: mice, frogs, a feather, fishes, and insects. We hypothesise that such silica transformation may have contributed to preservation of the megafossils by stabilization of the remains of biota and protection of the remains against dissolution.
The ostracod fauna from the middle Pleistocene Naganuma Formation (ca. 0.5 Ma) in the Sagami Group near Tokyo Bay, central Japan, was investigated. This study reports for the first time an ostracod fauna around 0.5 Ma in the marine oxygen isotope stage (MIS) 13 of Japan. This fauna consists of 58 species, and three assemblages were defined by Q-mode cluster analysis. The depositional environment of each assemblage can be defined as (1) outer bay, influenced by the open sea with relatively high salinity, (2) inner bay, with relatively low salinity, and (3) central bay, with intermediate salinity level between those of (1) and (2). A decrease in water depth occurred from the outer bay through the central bay to the inner bay during the depositional period of the studied horizons. The three most abundant species of each assemblage are Krithe japonica, Bicornucythere bisanensis and Amphileberis nipponica. The fossil fauna does not include the shallow-bay species Neomonoceratina delicata, currently found south of the Japanese main islands. This result is consistent with previous palaeobiogeographical studies of Japanese bay-dwelling ostracods. Its absence near Tokyo Bay at 0.5 Ma would be due to the distance from its original southern habitats and timing of the species' northward migration.
A mammal tooth discovered from the upper Eocene Ergilin Dzo Formation of southeastern Mongolia is identified as an upper second molar of a small amphicyonid (Mammalia: Carnivora). It is similar to Cynodictis, which is a primitive amphicyonid from the late Eocene to early Oligocene of Europe, in overall size, relative size of the trigon cusps, and smooth lingual cingulum. However, it differs from Cynodictis and other amphicyonids in having an extremely thick lingual cingulum that bulges posterolingually and a parastyle that positions anterior to the paracone, indicating that it belongs to a new genus of the family. Reappraisals of previously reported “Cynodictis” materials from the Paleogene of Asia imply that none of them belong to the Amphicyonidae, and only the present material confirms the existence of an amphicyonid in the Eocene of northern East Asia. This opens questions on the previously proposed existence of Cynodictis and migration of amphicyonids in the Paleogene of Asia.
Three species of the Middle Permian echinoconchoide brachiopod Vediproductus from the Kamiyasse area, northeast Japan, V. mugenjin sp. nov., V. punctatiformis, and V. sp., are described, and their paleogeographic significance is discussed. V. mugenjin sp. nov. is characterized as having spine bands on both the outer and inner surface of the valve, showing a strong relief with a comparatively wide interval of each band and a typical sawtooth outline of spine bands in cross-sectional view. The stratigraphic and paleogeographic distributions suggest that the genus flourished in the Tethyan province and was possibly restricted to a lower latitude than warm-cool water transitional environment.
Although the modern lesser panda (Ailurus; Ailuridae; Carnivora; Mammalia) only lives in the temperate highland forests of the southern Himalayan region, its fossil remains of late Miocene to Pliocene age have been found widely across the Holoarctic region. Very few mandibles or lower teeth of these animals, however, have been identified. Here, we provide a detailed description of the mandible and lower dentition of a large-sized lesser panda, Parailurus baikalicus (Sotnikova, 2008), which has been discovered from the middle Pliocene of Udunga, Transbaikalia, Russia. In the Transbaikalian species, lower molars are low crowned and shows highly crenulated enamel pattern. The main cuspids of cheek teeth are heavily worn horizontally, suggesting a high specialization for leaf eating. The distinctive lower tooth morphology of P. baikalicus differs from those of other fossil lesser pandas discovered from Europe and North America and from those of modern species, suggesting that the morphology found in P. baikalicus is derived in the Ailuridae.
This contribution describes and interprets fossil hyracoids from four localities in the Peri-Tethys region and one in East Africa. Two of the Peri-Tethyan localities (Ad Dabtiyah, Saudi Arabia and Reguba, Libya) are of basal Middle Miocene age (MN 5=P III, ca. 16.5 Ma), the third (Beglia, Tunisia) is basal Vallesian (ca. 11–10.5 Ma) and the fourth (Maragheh, Iran) is Late Miocene (MN 12=P VII, ca. 9.5–7 Ma). The East African locality, Bukwa, Uganda, is basal Middle Miocene in age (ca. 17.5 Ma). A new genus and species of hyracoid, Regubahyrax Selleyi, is described from Libya, characterised by lower molars ornamented by well developed cristids and spurs and a new species, Prohyrax bukwaensis, is described from East Africa, intermediate in dimensions between Prohyrax tertiarius from the Early Miocene of Namibia, and Prohyrax hendeyi from the basal Middle Miocene of the same country. The Saudi Arabian hyracoid is attributed to Afrohyrax championi and the Tunisian and Iranian ones to Pliohyrax kruppi or rossignoli and Pliohyrax graecus, respectively.
The micro-bivalve Carditella iejimensis is less than 3.5 mm in shell height and lives in the surface sediment within a submarine cave at Ie Island, Okinawa Islands, Japan. A previous study interpreted that δ 18O-derived temperature obtained from C. iejimensis shells indicates the water temperature between May and July of each year. This interpretation is based mainly on a statistically significant correlation between shell size and δ 18O values obtained from empty shells. To assess the validity of this interpretation, we performed high-resolution isotopic analyses on 19 empty shells with the aim of examining ontogenetic variation in δ 18O values. The results reveal no systematic variation in δ 18O values, inconsistent with the previous interpretation. Our data indicate little or no influence of growth duration (shell size) on the δ 18O values of shells greater than 1 mm in height.
A checklist of Cenozoic species-group names of Campanile Bayle in Fischer, 1884 is presented. It includes 101 species-group names. Among them, 98 species-group names were found to be available, four were nomina nuda, one was an incorrect original spelling, and two were incorrect subsequent spellings. Two new replacement names, Campanile douvillei nom. nov. and Campanile martini nom. nov., are proposed herein.
Three rugose species of the family Holmophyllidae Wang, 1947 are described for the first time from the Gionyama Formation of the Kurosegawa Terrane, Southwest Japan. They are Holmophyllum sp., Holmophyllum? sp., and Labechiellata reguloris (Sugiyama, 1939). These species are found in the Middle Member of the Gionyama Formation, which is Late Llandovery to Early Ludlow (Silurian) in age. Holmophyllum and Labechiellata are typical cosmopolitan genera. The compound holmophyllids such as Labechiellata may indicate tropical environments and suggest that ‘Proto-Japan’ was, like other areas that yield these corals, located in subtropical to tropical latitudes during the Silurian.
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