Fossils of Microporina species were collected and examined from the Soebetsu Sandstone Member of the Pleistocene Setana Formation in southwestern Hokkaido. A description is provided for M. japonica Canu and Bassler, and four species (M. sakakurai, M. minuta, M. quadristoma and M. soebetsuensis) are newly described. Some of them were previously reported as M. articulata (Fabricius). Among the five species, three (M. japonica, M. sakakurai, M. minuta) have a semielliptical or elliptical orifice, relatively large and deep frontal pseudopores, opesiules occluded with a thin plate showing vein-like surface sculpturing, and avicularia that are longer than wide. The other two (M. quadristoma, M. soebetsuensis) have a rounded-quadrate orifice (sometimes with a convex proximal margin), smaller frontal pseudopores, opesiules occluded but lacking vein-like surface sculpturing, and avicularia that are circular or wider than long. Marked orificial dimorphism is observed in two species, M. sakakurai and M. soebetsuensis.

The first detailed, systematic record of Silurian ostracod crustaceans from Vietnam is presented. Ostracods from the upper Silurian (upper Ludlow–lower Pridoli) Si Ka Formation of Ha Giang Province, northern Vietnam comprise ca. 10 species, including two new species of hollinoideans, two beyrichioideans, three species of eridostracine, at least one putative paraparchitoidean, and two indeterminate palaeocopid species. The fauna co-occurs with macroplant and fish fragments, and pterineid bivalves, in lithofacies that are interpreted as estuarine. The presence of beyrichioideans is consistent with their reported occurrence in marine, marginal-marine and estuarine ostracod assemblages elsewhere in the late Silurian and Devonian. One of the beyrichioidean species possibly represents Qujingsia nonaculeata, a species known from the Ludlow–Pridoli of South China, thus endorsing the supposed late Silurian age of the Vietnam fauna and its paleogeographical position on the South China paleo-plate. The other beyrichioidean is Beyrichia (Beyrichia), a globally distributed taxon in the Silurian and Early Devonian. Three species of eridostracine are referred to Cryptophyllus, a genus with a global distribution and temporal range from the Ordovician to Carboniferous. Hollinoidean taxa, whilst endemic at the genus-level, show affinities with glossomorphitine and sigmoopsinae taxa from Europe.

Six early late Maastrichtian (Late Cretaceous) ammonoid taxa are reported from the Krasnoyarka Formation of the Yezo Group in the Naiba area, southern Sakhalin, Russian Far East. These taxa are grouped into “immigrant species”, i.e., those that migrated from other regions (Pachydiscus subcompressus, Anagaudryceras mikobokense, Gaudryceras seymouriense and Zelandites varuna) and “indigenous species” with a North Pacific distribution (Anagaudryceras matsumotoi). It is unclear to which group Tetragonites sp. belongs. Zelandites varuna and G. seymouriense occur in both the lower upper Maastrichtian as well as the upper lower Maastrichtian in southern Sakhalin, but they have never been found in the middle Maastrichtian. The appearance of these two species in the cold-water regions, i.e., North Pacific and Antarctic, as well as intermediate southern mid-latitudes regions suggests that cooling events occurred during the late early and early late Maastrichtian in the Northwest Pacific region. Their disappearance during the middle Maastrichtian may indicate that the Northwest Pacific region was affected by the greenhouse Middle Maastrichtian Event (MME). This hypothesis suggests that the influx (e.g. P. subcompressus and A. mikobokense) and reappearance (e.g. Z. varuna and G. seymouriense) of many immigrant species into the Northwest Pacific region during late Maastrichtian time may have been associated with the post-MME cooling.

Over 100 well-preserved dissociated ophiuroid arm ossicles, i.e., lateral arm plates, dorsal arm plates, ventral arm plates, vertebrae and arm spines, were recovered from the upper Pleistocene Kioroshi Formation in the core of borehole GS-NY-1 at Nagareyama, Chiba Prefecture, central Japan. Following comparison with the lateral arm plates of ten extant amphiurid species occurring in the seas around Japan and with previously published fossil taxa in this family, the ossicles from Nagareyama were identified as belonging to the extant species, Amphiura multispina. This is the first fossil record of this form and the stratigraphically youngest of the Amphiuridae. The taphonomy and paleoenvironment of the brittle star fossils described are also discussed.

More than 23 extinct species and 10 extant species of the Balaenopteridae are known. Our knowledge of the family Balaenopteridae is increasing quickly, however, few fossil records support a circum-North Pacific distribution of balaenopterid genera and species. Because of limited preservations, most rorqual fossils reported from the western North Pacific can only be identified to the family level. A skull from the Shinazawa Formation (late Pliocene to Early Pleistocene) in Yamagata, Japan, is identified as aff. Balaenoptera bertae by possessing two diagnostic features of the species: large occipital condyles, and a posteriorly elongate postglenoid process. Combination of four more features also support that the specimen is a closely related to B. bertae. The specimen is probably a slightly older individual than the holotype of B. bertae, based on the estimated bizygomatic width and slightly longer posterior process of the tympanoperiotic. The first and only report of B. bertae was from the Pliocene Purisima Formation in California, USA. The specimen from Japan is incompletely preserved, but shows the occurrence of B. bertae in the western North Pacific for the first time, as many living balaenopterids are distributed across the North Pacific, such as Balaenoptera musculus, B. physalus, B. borealis, B. acutorostrata, and Megaptera novaeangliae.

The Early Cretaceous Kuwajima Formation, Tetori Group, Japan has yielded various aquatic and terrestrial vertebrates, but lissamphibian records are limited to albanerpetontids and an isolated longbone of a frog. Here we provide the first report of an associated frog specimen from the Tetori Group. The specimen is composed of a few skull elements and several postcranial bones, including the femur, ilium, and vertebrae. This new Tetori frog is distinguished from the previously reported Early Cretaceous Asian genera, Liaobatrachus from China, and Hyogobatrachus and Tambabatrachus from Japan, in having hatchet-shaped sacral diapophyses and a posteriorly tapering urostyle with a weakly developed dorsal crest. Phylogenetic analysis of this new material places it as a non-neobatrachian frog that may be related to previously described Chinese and Japanese taxa, but more complete material would be needed to establish its affinities with confidence.

A fragmentary and the largest single bone element from the Lower Cretaceous Kanmon Group in Kyushu Island, southwestern Japan reported yet to date is described. This specimen has a fossa and lenticular foramen on its lateral surface and internal chambers of both large and small sizes. It was identified as the cervical vertebra of a titanosauriform sauropod dinosaur mainly based on such pneumatic structure. This specimen represents the first titanosauriform to be described from the Kanmon Group.

Conglomerate of the Lower Jurassic Kuruma Group contains microfossil-bearing clasts. In the present study, these microfossils were investigated via the hydrofluoric acid (HF)-etched surfaces of the clasts and residues produced during acid treatment. As a result, Permian (mainly Guadalupian–Lopingian) radiolarians were obtained from mudstone and chert clasts; spicules of indeterminate age were obtained from the chert clasts. The mudstone clasts were derivable from the Akiyoshi, Ultra-Tamba, Maizuru, and/or Hida-Gaien belts or equivalent units, while the spicule-dominated chert clasts likely originated from the Akiyoshi belt or equivalent units. Except for tuff and acidic volcanic rocks, the clast components of the Kuruma Group in this study are similar to the component rocks of the Akiyoshi belt.