In mammals, the recurrent laryngeal nerve (RLN) loops around the ligamentum arteriosum on the left side and around the subclavian artery on the right side. It is generally considered that such an asymmetric arrangement of the right and left RLN is brought about by a transformation of the aortic arches at an early stage of embryonic development. We have dissected rough-toothed dolphins and Pacific white-sided dolphins in this study. In both species, the right RLN hooked around the costocervical trunk, while the left RLN hooked around the ligamentum arteriosum. The external carotid artery, the internal carotid artery, the subclavian artery, and the costocervical trunk arose radially from the brachiocephalic trunk on the right side. The left costocervical trunk arose directly from the aortic arch. The right and left subclavian arteries ran ventral to the subclavian vein and the vagus nerve, in a similar manner to the secondary subclavian arteries in birds. These findings suggest that the replacement of the primary (or dorsal) subclavian artery by the secondary (or ventral) subclavian artery might occur at a certain embryonic stage in dolphins as well.

We examined the food habits of the Asiatic black bear in relation to availability of main foods (seeds of Fagus crenata, Quercus crispula, and Q. serrata) from 1213 scats in Shirakawa Village, Gifu Prefecture, Japan, over seven years. The study area comprises natural forest (approximately 88%) and had little bear-human conflict. The food composition was different in all months over the years. The bears mainly fed on green vegetation in spring, until the end of July, and on hard mast in autumn when its production was abundant. Insects, such as the Formicidae family, made up a higher proportion of the diet from July to August. In autumn of low hard-mast production, the bears consumed various fleshy fruits. The annual variation in food composition was especially greater in September because of the fluctuation in fruit production rather than a phenological time lag.

This study surveyed the relative usage, amount of food, and consumption of food of deer in three habitat types as artificial forests located more than 1 km away from an artificial grassland (hereafter FO), forest edges located within 50 m from the artificial grassland (hereafter FE), and the artificial grassland (hereafter AG). The relative usage by deer of the three habitat types was evaluated by using motion-triggered cameras, and the amount and consumption of food were evaluated through a comparison of plant biomass within and outside fences (control). The relative usage of AG was much higher than that of other habitat types except in winter. The relative usage of FO was generally lower than that of other habitat types but increased in winter. The plant biomass of control in AG was significantly lower than that of fence in AG regardless of season. The plant biomass of control in FO was significantly lower than that of fence in FO only in winter. This study showed that sika deer preferentially selected artificial grasslands but used forests in winter. The mosaic landscape of artificial grasslands and forests is the most suitable landscape for sika deer.

We examined whether the shapes of the teeth could be used to distinguish morphological differences of modern Sus scrofa between subspecies, and between regions. The occlusal outlines of the lower teeth of five populations of the Ryukyu wild boar (S. s. riukiuanus) and two populations of the Japanese wild boar (S. s. leucomystax) were photographed and digitized into landmarks. The landmark coordinates were statistically compared among the populations. As a result, correct assignment rates of the populations based on their tooth shape was the highest for the fourth deciduous premolar. Pairwise test detected significant differences in tooth outline shape between the two subspecies. In addition, the tooth outline shapes of geographically adjacent populations tended to be similar. The results in this study indicated that the evaluation of tooth outline shapes, especially that of the fourth deciduous premolar, is a powerful approach for distinguishing subspecies of S. scrofa as well as for evaluating geographic variation among them. This method is useful in archaeological and paleontological studies because of its applicability for isolated teeth, and has potential to increase our understanding about the history of macroevolution, migration, and introduction of S. scrofa in the Japanese archipelago.

This study presents a compilation of fossil and archeological records of the Ryukyu long-furred rat Diplothrix legata, a murid rodent endemic to the central part of the Ryukyu Archipelago (Amami and Okinawa Islands) of Japan, in order to further understand the distributional history of this endangered species. Although the species is currently confined to restricted forest areas on three islands (Amamioshima, Tokunoshima, and Okinawajima), fossiles or archeological occurrences have been reported at several extralimital localities on these islands, as well as on three other islands (Okinoerabujima, Kumejima, and Miyagijima). The records from the small island of Miyagijima are most likely remains from animals artificially brought to the island. The southern part of Okinawajima is devoid of Holocene records of the species during and after the Gusuku Period (from the 11th to 15th centuries Current Era [CE]) except for a single case. The species' decline in this area has been attributed to human activity in the Gusuku Period.

In the testis of the Sunda porcupine (Hystrix javanica), the distribution pattern of cytoskeletal proteins was immunohistochemically examined to understand their functional roles in the testis. Immunoreactivity for α-smooth muscle actin (SMA) was found in the peritubular myoid cells of the seminiferous tubules and in the sub-tubular myoid cells of epididymal ducts. In intermediate filaments, desmin was exhibited in the sub-tubular myoid cells of the epididymal ducts, and vimentin immunoreactivity was detected in the Sertoli cells, Leydig cells, peritubular myoid cells, and sub-tubular myoid cells of the epididymal ducts. However, cytokeratin was not expressed in the testes or epididymides. Strong immunoreactivity for vimentin was demonstrated between the infranuclear part of the elevated nuclei and the basal membrane in the Sertoli cells. Furthermore, vimentin was extended from supranuclear to apical parts in some Sertoli cells. Immunoreactivity for α-tubulin was detected only in the Sertoli cells. It is concluded that, in the porcupine testes, desmin plays no role in the contractile function of peritubular myoid cells, vimentin may contribute to the anchoring and transition of the elevated nuclei in the Sertoli cells, and α-tubulin and vimentin in the Sertoli cells are likely involved in their structure and function as the main cytoskeleton.

The Jarman-Bell Principle among ungulates explains that larger species feeding on high-fiber foods have developed fermentation chamber such as rumen than smaller species feeding on low-fiber foods. Among arboreal squirrels, it seems that larger Petaurista species feed on high-fiber leaves and smaller species feed on low-fiber fruits and seeds. Therefore, relative length of the cecum may be positively correlated with body mass which is associated with tendency of folivory. To test this hypothesis, we examined body mass, head-body length, and the alimentary tract lengths (small intestine, cecum, colon, large intestine, and total intestine) of 13 arboreal squirrel species (n = 19) from six genera. Spearman rank correlation analysis showed that larger folivorous Petaurista had a longer fermentation chamber. Smaller granivorous squirrels might have longer small intestine. These differences in alimentary tract morphology of arboreal squirrels could reflect feeding adaptation.

The silky short-tailed bat (Carollia brevicauda) is common and widely distributed in the Neotropic; however, data on reproductive biology is scarce. Here, we present the results of a monitoring of two colonies in the Andes of Colombia. The high recapture rate allowed us to estimate the length of pregnancy, lactation, and between-births interval. Results showed that this species reproduced with low synchrony throughout the year and may exhibit a polyoestry reproductive pattern with oestrous postpartum that lasts around eight months. The pregnancy length was two and a half months to three months and lactation length was one and a half month to two months. Males also showed reproductive activity throughout the year. The asynchronous reproduction of this species at the study area suggests that factors related to body condition may be more important for timing of reproduction than environmental cues. The reproductive life-history traits of this species are similar to other species of the genus Carollia and Phyllostomidae family.