This study investigated an early Pleistocene ostracod fauna from the Kazusa Group in the Tama Hills (ca. 1.7-1.4 Ma) along the western side of Tokyo Bay, central Japan. We report for the first time an early Pleistocene ostracod fauna from the Kanto District. This fauna consists of 56 species, with three assemblages defined by Q-mode cluster analysis. The two most abundant species are Bicornucythere bisanensis and Spinileberis quadriaculeata in the assemblage BS, Pontocythere subjaponica and Buntonia hanaii in the assemblage PB, and Loxoconcha ikeyai and Pontocythere subjaponica in the assemblage LP. These assemblages indicate the following depositional environments: (1) the innermost to central area of an inner bay having relatively low salinity (assemblage BS); (2) the outer area of the inner bay and upper-shelf area influenced by open sea water with relatively high salinity (assemblage LP); and (3) the central to outer area of the inner bay having salinity intermediate between that of (1) and (2) (assemblage PB). We also report first occurrences on the Pacific side of Japan near Tokyo Bay for two cryophilic taxa, Laperousecythere robusta and Pectocythere sp. Laperousecythere robusta moved southward from the Japan Sea coast, probably through the Tsugaru Strait before reaching central Japan near Tokyo Bay by 1.6 Ma. Pectocythere sp. might have first appeared around Tokyo Bay during the early Pleistocene by 1.6 Ma. The species content of the assemblage BS suggests that Bicornucythere and Spinileberis commonly inhabited inner-bay areas near Tokyo Bay by 1.6-1.4 Ma at the latest. This fossil fauna does not include inner-bay species of the genera Neomonoceratina and Sinocytheridea. Their absence near Tokyo Bay in the early Pleistocene is consistent with previous palaeobiogeographical findings regarding Japanese bay-dwelling ostracods. These data provide information about the route and timing of the northward or southward migrations of shallow-marine benthos along the Northwest Pacific margin during the late Cenozoic.

A new species of the genus Sinamia of the family Sinamiidae of the order Amiiformes, S. kukurihime is described on the basis of a hyomandibula and many isolated bones and scales found from the Lower Cretaceous freshwater deposits of the Kuwajima Formation, Itoshiro Subgroup, Tetori Group in Kuwajima, Hakusan City, Ishikawa Prefecture, Japan. The new species is distinguished from other congeners by the forms of the hyomandibular, frontal, dermopterotic, maxilla, gular plate, preopercle, supracleithrum and scales. Among the genus Sinamia, S. kukurihime sp. nov. is considered to be closest to S. liaoningensis. This is the first record of the genus Sinamia from Japan. The presence of a new species of the genus from Japan demonstrates the wide distribution and diversity of the genus during the Cretaceous in East Asia.

We identified 40 genera and 83 species of scleractinian corals from middle Pleistocene reef limestones on Irabu-jima, located in the South Ryukyu Islands (South Ryukyus); these data were then combined with previously published data sets on Pleistocene coral assemblages on Okinawa-jima (southern Central Ryukyus), and Kikai-jima (northern Central Ryukyus) to perform statistical analyses, including cluster analysis and multidimensional scaling (MDS) ordination of Bray—Curtis (BC) similarity coefficients applied to coral taxa (R-type analysis) and coral assemblages (Q-type analysis). Results of the analyses, combined with field descriptions of the coral assemblages, allowed interpretations of reef paleoenvironments. Outcrops of Quaternary reef deposits in the Ryukyus comprise both shallow- and deep-water coral assemblages. Generally, coral diversity increases southward along the island chain. The statistical analyses highlight differences in the taxonomic compositions of fossil coral assemblages in different geographic areas and in distinct reef environments. We report on the differences among assemblages on Irabu-jima, Okinawa-jima, and Kikai-jima. Upper reef slope coral assemblages on Irabu-jima, which are similar to those on Okinawa-jima, are dominated by acroporid corals, mainly Isopora palifera and branching Acropora spp., encrusting to platy Porites spp., and branching Pocilloporidae. Porites spp. and faviids, such as Cyphastrea spp. and Favia pallida gr., are more typical of the upper reef slope on Kikai-jima. Lower reef slope assemblages on Irabu-jima are dominated by thin laminar colonies of Porites and/or Montipora species. Associated coral taxa are Stylocoeniella sp., Leptoseris spp., small fungiid corals, Trachyphyllia geoffroyi, and Montastrea valenciennesi. Data from two large outcrops on Irabu-jima highlight the relatively large spatial homogeneity of community structures in lower reef slope coral assemblages as compared with their upper reef slope counterparts.

Permianellids are a specialized fossil group of Brachiopoda characterized by a complicated forking lobe system. In this paper, we report two permianellid species (Pararigbyella doulingensis Shen and Zhang, 2008 and Dicystoconcha lapparenti Termier and Termier in Termier et al., 1974), from the middle Guadalupian (Wordian, middle Permian) of the Kamiyasse-Imo area, South Kitakami Belt, Northeast Japan, of which Pararigbyella doulingensis is the first record in Japan. A global review of all occurrences of the two genera suggests that Pararigbyella is restricted to the Cathaysian Province, while Dicystoconcha is mainly distributed in the Paleotethyan region and the two transitional zones between the Boreal or Gondwanan and Paleotethyan realms.

The Permian large gastropod “Pleurotomaria” yokoyamai Hayasaka was found for the first time from the Capitanian (upper Guadalupian) Iwaizaki Limestone in the South Kitakami Belt, Northeast Japan. A smaller planispiral gastropod Porcellia sp. was found in association with it. These taxa have been scarcely reported, except from the coeval Permian limestones at Akasaka in Southwest Japan and in the Balya Maden area, western Turkey. The Akasaka Limestone was deposited as a low-latitude atoll on a mid-Panthalassan seamount, whereas the Iwaizaki Limestone was laid down as a patch reef within a terrigenous clastics-dominated facies on a shallow marine continental shelf. The occurrence of this unique assemblage suggests that the Iwaizaki Limestone originated also in a Permian low-latitude domain, and that the South Kitakami Belt likely formed a part of the continental margin of South China, representing its eastern extension to Northeast Japan.

The ichthyopterygian Utatsusaurus hataii Shikama et al. 1978 is the only valid reptilian taxon known from the Lower Triassic Osawa Formation in Minamisanriku Town, Miyagi Prefecture, which records the recovery of the marine ecosystem shortly after the end-Permian mass extinction. In this paper, we describe a fragmentary specimen of an indeterminate ichthyopterygian which is distinguished from Utatsusaurus hataii based on rib morphology. The discovery of a previously unknown ichthyopterygian implies that the taxonomic diversity of the reptilian fauna of this formation is higher than previously assumed.