A fragmentary femur of the Rhinocerotidae (Perissodactyla, Mammalia) from the lower Miocene Yotsuyaku Formation of the Shiratorigawa Group, Ichinohe, Iwate Prefecture, Northeast Japan is redescribed, and the fossil record of Japanese early Miocene rhinocerotids, including footprints, is briefly reviewed. The femur is identified as belonging to an indeterminate species of rhinocerotid, cf. Aceritherini, in having the distal portion of the base of the lesser trochanter situated near the apex of the third trochanter and a less projected third trochanter than in most rhinocerotids. Since ca. 20 Ma, rhinocerotids have inhabited and been widely distributed in Japan, which formed an eastern margin of continental East Asia at that time.

This paper describes microgastropod fossils from the Kasimovian (late Carboniferous) limestone float collected from the Mizuboradani Valley, Fukuji, Okuhida-onsen-gou, Takayama City, Gifu Prefecture, central Japan. The microgastropod assemblage consists of a diversity of larval and/or early juvenile shells and represents late Palaeozoic cosmopolitan taxa, including Euomphalidae, Pleurotomarioidea, Anomphalidae, Naticopsidae, Trachyspiridae, Goniasmatidae, Orthonematidae, Pseudozygopleuridae, Subulitidae, Meekospiridae and Streptacididae. The microgastropod assemblage bears some resemblances to those from the early Carboniferous of New South Wales, Australia, and those from the latest Permian of Guangxi Province, China.

Researchers disagree on the identity of dinosaurs that left footprints in the Lower Cretaceous Tetori Group of the Oshirakawa area (Japan). To clarify these identities, we quantitatively analyzed footprint data obtained from three-dimensional laser scanning technology. From these data, we identified six tracks belonging to dinosaurs. These six tracks were bipedal with a tridactyl morphology, which we could differentiate into large theropods (the ichnofamily Eubrontidae) and large ornithopods (similar to Amblydactylus-type). Our results indicate that the ichnofauna of the Oshirakawa site is richer than previously thought. Additionally, the cooccurrence of large theropod and Amblydactylus-type ornithopod footprints in the Oshirakawa area is the oldest in the Tetori Group (although a similar assemblage was identified in the Kitadani Formation, which is the uppermost part of the Tetori Group). Thus, quantitatively assessing dinosaur footprints using 3D digital data is an effective approach to identify dinosaur footprints.

The external area-to-volume ratio of the ammonite shell has been held to be related to morphology but never evaluated quantitatively. A dimensionless ratio, the Vogel number, was computed for large samples of Devonian to Cretaceous ammonites with a new method based on the ADA-model. The estimated ratios range from 2.4 to 3.4. The highest values are exhibited by uncoiled serpenticone ammonites, lowering in the sequence serpenticone-oxycone-spherocone. It is shown that the area-to-volume relationships are controlled by the involution (degree of overlapping) and the relative width of whorl section. The typical evolutionary trends serpenticone–spherocone and/or serpenticone–oxycone, broadly documented through the history of the Ammonoidea, could have been driven, at least in part, by the lowering of the area-to-volume ratio.

A percoid fish from the middle Miocene freshwater beds of Iki Island, Nagasaki, Japan is described as a new species, Siniperca ikikoku of the family Sinipercidae based on three specimens. It is characterized by having 11 abdominal and 16 caudal vertebrae; 11 dorsal fin spines and 12 soft rays; three anal fin spines and eight soft rays; four large spines on the ventral arm and several short processes on the posterior margin of the preopercle; the first spine of the dorsal fin longer than half the second spine of the dorsal fin. This is the third known fossil species of the genus Siniperca and the second Miocene species of the genus. After the Miocene, fishes of Siniperca went extinct in Japan, because the large lakes and rivers disappeared in Japan. They were adapted to and dispersed in large rivers and lakes in China and Korea.