Well preserved molluscan fossils of Olenekian age (Early Triassic) were obtained from the upper part of the Bac Thuy Formation in Lang Son City, northern Vietnam. We report here an ammonoid, Xenoceltites variocostatus Brayard and Bucher, and describe two bivalve species, Crittendenia australasiatica (Krumbeck) and Crittendenia langsonensis sp. nov. Xenoceltites variocostatus is a characteristic species of the uppermost Smithian Anasibirites ammonoid zone and the earliest Spathian Tirolites ammonoid zone. Crittendenia australasiatica and C. langsonensis may thus be significant diagnostic species suggesting a middle Olenekian age. In addition, these occurrences demonstrate a probable faunal exchange between the eastern Tethys and eastern Panthalassa during the Olenekian, because many species of Crittendenia have been reported from Asia and from Panthalassic basins in the United States.

We present high-resolution, three-dimensional carbon (δ13C)- and oxygen (δO)-isotope compositions from calcite shells of two modern brachiopod species (Terebratulina crossei and Terebratalia coreanica) and their correlative relationships. δ¹³C and δ¹⁸O values from the secondary shell layer, which constitutes the main body of a brachiopod shell, are in and/or out of the range of δ13C and δ18O values of calcite precipitated in isotopic equilibrium with ambient seawater (equilibrium calcite). The δC and δ18O values of samples from the outermost part of the secondary shell layer show positive correlations. The values of high-growth-rate portions are less than those of low-growth-rate portions; these results are ascribed to a kinetic isotope fractionation effect. Metabolic influences are identified in the isotopic compositions of the low-growth-rate portions for T. coreanica, resulting in decreases in δ13C values compared with those of equilibrium calcite. We illustrate the effects of kinetic isotope fractionation and metabolism on the isotopic compositions of brachiopod shell calcite, which vary among shell portions within a single shell, as well as between the two species. However, appropriate selection of brachiopod taxa and shell portions that reflect the isotopic composition of ambient seawater enables their use as a reliable paleoenvironmental proxy.

The discovery of an extremely well preserved new juvenile specimen of Sapeornis provides more anatomical information about this basal avian, and documents the first avian specimen from the Jehol Biota with detailed foot-pad integument preserved. This is the first Sapeornis specimen with a well preserved carpal X, astragalus and calcaneum. Seven major skeletal components from five well preserved juvenile and adult skeletons of Sapeornis were measured. The allometric differences associated with growth are shown to be distinct; all linear regressions resulted in high correlation coefficients consistent with a single growth series. The number of sacral vertebrae and free caudal vertebrae vary during ontogeny, and this may indicate that all the specimens can be assigned to a single species: Sapeornis chaoyangensis.

A theropod tooth found in the Upper Cretaceous Himenoura Group in the Koshikijima Islands, Kagoshima Prefecture, is described. Recent paleontological work in the region suggests a middle Campanian age for the specimen. Lacking a feature diagnostic of any specific theropod clade, this specimen is considered merely as Theropoda incertae sedis. The present finding confirms the potential of the Himenoura Group as a new source of information on the diversity of Theropoda during the Campanian.

Gaudryceras hobetsense sp. nov. is described from the Nostoceras hetonaiense Zone (= lowest Maastrichtian) of the Hobetsu area, south-central Hokkaido, Northern Japan. Its shell is characterized by fine lirae on early whorls, distant rounded or flat-topped, narrow band-like ribs on middle and later whorls, and frequent collar-like ribs on later whorls. The occurrence of this new species strongly suggests the presence of lowest Maastrichtian strata in southern Alaska, and sheds light on the age delineation of the chronologically poorly defined beds in northern and eastern Hokkaido.

The aragonitic micro-bivalve Carditella iejimensis, which is less than 3.5 mm in height and length, inhabits the sediment surface in a submarine cave off the Okinawa Islands, Japan. To evaluate the use of this species as a quantitative paleoceanographic proxy, we analyzed the δ¹⁸O values of 50 living C. iejimensis specimens collected from the Daidokutsu submarine cave (ca. 30 m water depth). Results show that most individuals (96%) preserve δ¹⁸O values corresponding to the mean annual temperature and δ¹⁸O of seawater. The mean δ¹⁸O_shell of the 50 specimens was -1.10 ± 0.18‰. These results, when applied to fossil shell δ¹⁸O records from Daidokutsu cave, indicate that its mean annual surface water temperature is about 1°C higher than temperatures during the Medieval Warm Period and the Middle Holocene Climatic Optimum, and that the recent warming is likely exceptional during the past 7000 years.

Shell microstructures of five solemyid species from Japan were characterized by scanning electron microscopy. All five species examined had outer and inner shell layers, and were categorized into four groups according to the shell microstructure composition. Group 1 consist of Solemya (Petrasma) pervernicosa and Solemya (Solemya) tagiri. The outer layer of their shells is characterized by radially elongate simple prismatic structure (RESP) type A, and the inner layer by irregular prismatic structure. Group 2 is represented by Solemya (Solemya) pusilla. The outer layer of its shell has RESP type B structure, and the inner layer structure is homogeneous. Acharax japonica is in Group 3. Its outer shell layer has RESP type C, and the inner layer is characterized by laminar, homogeneous, and irregular complex crossed lamellar structures. Group 4 is represented by Acharax johnsoni. Its outer shell layer has a reticulate structure and the inner layer has a cone complex crossed lamellar structure. Reticulate microstructures have never before been found in shells of any molluscan species. These groupings indicate that these solemyid species have a variety of shell microstructures, but the groups are not consistent with previous solemyid systematics at the generic and subgeneric level. Solemyid shell microstructures may provide crucial signals for their phylogenetic grouping, but their significance is not clear from analyses of morphological characters only. In future studies, the utility of microstructural characteristics should be confirmed by mapping the character states of a larger taxonomic sample onto molecular phylogenetic trees.

We present a detailed dataset of planktonic foraminiferal biohorizons to enhance a biostratigraphy for the eastern equatorial Pacific. Middle Miocene to Pleistocene planktonic foraminiferal biostratigraphy is established using 269 samples from Cores 1H to 40H recovered from Integrated Ocean Drilling Program (IODP) Hole U1338B. In addition to the onboard study of Hole U1338A, a total of 60 biohorizons are recognized with three grades of reliability. Generally, these biohorizons are in agreement with each other and consistent with shipboard magnetostratigraphy, except for several discrepancies that may be caused by ecological diachronous processes. The studied sequence can be correlated with Zone M7 to Subzone PT1b. However, we cannot detect Miocene zones M6, M10, and M12 in this sequence because of discrepancies in some zonal marker biohorizons.