The Tetori Group, which crops out in the Inner Zone of central Japan, has been extensively studied for its rich floral and vertebrate fossil assemblages. The authors provide the first contribution to the palynoflora of the Kitadani Formation, which has been dated as late Barremian to early Aptian on the basis of the freshwater bivalves recorded from it. The studied assemblage yields 45 genera and 41 species of spores and gymnosperm pollen grains, some freshwater algae, one epiphyllous fungus, and various plant fragments. No angiosperm pollen grains were observed. Some forms described here in detail are not yet known from the literature. They probably correspond to new species, but the scarcity of the specimens has caused us to place them temporarily in open nomenclature. This palynological study adds new data to the present knowledge on the Barremian-Aptian Tetori-type Paleoflora of eastern Asia. The authors compare the palynological inventory with recently published data obtained from the Barremian strata of the Choshi Group, the Outer Zone of Southwest Japan. Then, they situate the results among the previous paleoenvironmental reconstructions of the Tamodani Flora, and confirm a warm temperate and moderately humid climate, with locally drier conditions. Even if some elements of the assemblage suggest transportation, all of them are of continental origin and confirm a fluvio-lacustrine environment for the deposition.

Three odontaspidid fossil shark teeth previously reported from the “Lower Formation” of the Upper Cretaceous Mifune Group in Yamato Town and Mifune Town, Kumamoto, Japan as three separate taxa (“Carcharias” amonensis, “C.” cf. amonensis, and “Carcharias” sp.) are reexamined and described in detail. Restudy shows that all of these shark teeth should be assigned to the species “Carcharias” amonensis. These specimens establish that “C.” amonensis also inhabited the Pacific region and thus had a worldwide distribution in the temperate sea in the Cretaceous.

Other than trilobites and ostracods only a few species of arthropods are known from the Palaeozoic of Japan. Here we describe a new bivalved arthropod from the Lower Devonian of central Japan, Norikeya onoi gen. et sp. nov. It shows morphological similarities to both palaeocopine ostracods and phyllocarid malacostracans, but its systematic position remains uncertain. N. onoi lived in warm temperate shallow marine waters. Leperditicopid arthropods that occur in the same formation in central Japan are associated with the Early Devonian leperditicopid biogeographic province of South China, which concurs with the probable palaeogeographic position of central Japan based on other types of evidence.

The Ediacaran sediments in the Yangtze Block preserve valuable records of biological evolution and drastic climate changes. However, most of the Ediacaran fossil occurrences have been reported from the shallow platformal facies, and few fossils have been described from the deep basinal facies in the Yangtze Block. Here, we report mineralized microfossils from the basinal facies of the Ediacaran Doushantuo Formation at Fengtan in northwestern Hunan Province, China. The submillimeter-sized microfossils with oval-discoidal shapes have apatite walls of variable thickness. The lack of morphological regularity, ornamentation, and distinct apertures indicates that they are not protozoan shells or tests. The apatite walls have more likely replaced the recalcitrant organic walls of prasinophyte phycomata and/or algal resting cysts. These fell from shallow water and were quickly preserved in a deeper setting, associated with a local decline in pH caused by bacterial decomposition and elevated concentration of phosphate in seawater. This discovery provides new insight into the stratigraphic correlation between the shallow and basinal facies of the Chinese Ediacaran.

The tiny marine Cambrian ‘Orsten’ Cambropachycope clarksoni Walossek and Müller, 1990 (ca. 500 Ma), a derivative of the stem lineage toward Eucrustacea (= crown group), bore an unusual anterior projection of the head that has been designated a single compound eye. The cornea only of this eye has been preserved in three dimensions and in fine detail - unprecedented for a non-trilobite, Cambrian arthropod eye. Here we investigate the ultrastructure of this cornea. The cornea was found to be relatively thin and composed of three layers: an outermost and innermost layer of transparent material (a felt work of fibrils) and a hollow middle layer containing a dark material. This middle layer appears not to be an artefact of phosphatization or the consequence of moulting; probably it was present in the living, non-moulting-stage animal. The middle layer may have functioned as a filter - filled with pigmented oil that served to filter out the blue, scattered light from sunlight, thus enhancing the appearance of tiny light signals (i.e., potential prey). This adaptation would support the model lifestyle predicted from a study of the larger anatomy of C. clarksoni as a predator. However, the cornea of C. clarksoni remains enigmatic at this stage.

Patellogastropods are poorly recorded in sedimentary rocks. This hinders our understanding of their evolutionary and migratory history in the geologic past. The Middle Pleistocene Ichijiku Formation in the Boso Peninsula, central Japan, consists of sand wave deposits formed at 50 to 130 m water depth by unidirectional currents on a sea floor and contains an unusually well preserved and highly diverse patellogastropod assemblage. A total of 12 patellogastropod taxa have been collected: seven species of Cellana (Nacellidae), four species referred to as living Lotiidae, and one undetermined species of the family Lottiidae. Of the seven species of Cellana, five are described as new (Cellana yamamotoi sp. nov., C. bosoensis sp. nov., C. igniculus sp. nov., C. kobayashii sp. nov., and C. kamatakiensis sp. nov.), one is related to the modern C. toreuma (Reeve), and one poorly preserved taxon is unnamed but probably extinct. The assemblage represents a window into a Middle Pleistocene patellogastropod community in central Japan, which differs markedly from the modern fauna in the dominance of the genus Cellana. Selective extinction is noted for the genus Cellana. The habitat loss during the glacial lowstands of sea level is a plausible explanation for this selective extinction.

In this study, we explored the relationship between brain volume and brain width in a wide range of extant mammals and birds in an effort to determine whether brain width could be used as an appropriate variable for estimating the brain volume of extinct species. The relationship between brain volume and brain width in extant species was assessed using computed tomography images of mammalian skulls from 55 species representing 13 orders, and avian skulls from 64 species representing 21 orders. Brain volume and brain width showed a strong linear correlation in both mammals and birds. We also discovered that brain volume of extant as well as extinct mammals and birds can be estimated on the basis of brain width. The brain widths of Cynodontia, Triconodonta, and non-avian Theropoda were relatively narrower than those of extant mammals and birds. This data indicates that compared to their early ancestors, the brain width of both mammals and birds has increased with respect to brain endocast volume. Thus, on the basis of our results we have concluded that the relationship between brain volume and brain width is useful for estimating the brain volume of extinct mammals and birds. In addition, it was found that relative brain width of both mammals and birds has increased throughout their evolutionary history from early ancestors to extant species.