A total of 58 molluscan species was collected from the uppermost Lower Miocene Orito Formation at Kougasezaki, Sado Island, Niigata Prefecture. Fifty-two species, including six rocky shore gastropods are first recorded from the formation. Megacardita osawanoensis (Tsuda), Vepricardium okamotoi Taguchi, Timoclea itoigawae (Tsuda), Turbo (Marmarostoma) ozawai (Otuka), Haliotis notoensis Masuda and Littorinopsis miodelicatula Oyama are briefly described. These species suggest that the formation at Kougasezaki was deposited in the intertidal zone to 10–20 m depth, associated with a rocky shore environment.
Cenozoic pedunculate barnacles (Cirripedia, Thoracica) deposited in the paleontological collection of the Mizunami Fossil Museum, Japan, are clarified. Two new species of the scalpellid genus Arcoscalpellum Hoek are described: Arcoscalpellum s.l. isaonishikawai from the Miocene Bihoku Group and Arcoscalpellum s.l. joei from the Miocene Yotsuyaku Formation. Lepas azuminoensis Kawase, Koike, and Tanaka is moved to another lepadid genus, Dosima Gray. Smilium scorpio (Aurivillius) (Calanticidae), Lepas pectinata Spengler (Lepadidae), and Octolasmis orthogonia (Darwin) (Poecilasmatidae) from the Pleistocene of Japan are first reported in the fossil records. The new records of fossil pedunculate barnacles are as follows: Calantica sp. (Calanticidae) from the Pleistocene Ryukyu Group; Lepas sp. from the Miocene Katsuta Group; Oxynaspis sp. (Oxynaspididae) from the Pleistocene Atsumi and Shimosa Groups; and Capitulum sp. (Pollicipidae) from the Miocene Mizunami Group.
Munidopsis kaedetatsuyai, a new species of the squat lobster genus Munidopsis Whiteaves (Decapoda: Anomura) is described from the Higashibessho Formation (uppermost Lower–lowermost Middle Miocene) of the Yatsuo Group in Toyama Prefecture, central Japan. This is the first recognized species of the genus and the second record for Munidopsidae Ortmann from the Cenozoic of Japan.
James Carter first described Neptunus vectensis (now Portunus vectensis) in 1898 from several specimens, two of which were in the Woodwardian Museum, Cambridge, UK. All specimens he studied came from the Hampstead Beds, Isle of Wight, one of which was a partially preserved underside. Unfortunately, none of the specimens which Carter originally used can now be found (Quayle and Collins, 2012); therefore, a recently obtained and better-preserved specimen (IWCMS: 2020.424) is designated as the neotype for Neptunus vectensis and allows to re-describe the species.
Hemipneustes striatoradiatus (Leske) is a medium- to large-sized (up to c. 115 mm in length) holasteroid sea urchin that is locally common in the upper Maastrichtian (Upper Cretaceous) of the type area of that stage in the south-east Netherlands and contiguous Belgium. Tests of this species were bored both in vivo and post-mortem, and encrusted post-mortem, but evidence of predation by vertebrates in the form of tooth marks is surprisingly rare. A peculiar specimen from the upper Nekum Member (Maastricht Formation) preserves two clusters of parallel grooves in trapezoid groups, and on opposite sides of the test. These are interpreted as evidence of failed predation, namely the bite marks of a marine carnivore with a fairly large mouth and closely spaced teeth with a pointed, conical cusp and, possibly, smaller cusplets. The most probable culprit was a non-durophagous shark such as a representative of the families Scyliorhinidae Gill or Squalidae Bonaparte, but certain types of teleost fish (aspidorhynchids, saurodontids or ichthyotringids) cannot be ruled out either.
Mariaplax ohiranorikoae, a new species of the crab family Hexapodidae Miers is described from the Middle Pleistocene Atsumi Group of Aichi Prefecture, central Japan. This is the second record for Mariaplax Rahayu and Ng from the Pleistocene deposits of Japan. Hexapus anfractus (Rathbun) recorded from the Holocene Nanyo Formation is re-evaluated and identified with the extant species, Mariaplax chenae Rahayu and Ng.
Four molluscan associations, the Vicarya, the Cyclina-Anadara, the Sinonovacula-Hiatula, and the
Crassostrea, were identified from the Lower Miocene Kunimi Formation in the Ito Quarry, Kunimi-cho, Fukui Prefecture, central Japan. These associations suggest that the Kunimi Formation in Ito Quarry were deposited under the intertidal to subtidal zones. These molluscan associations are comparable to the tropical to subtropical Arcid-Potamid fauna (the lowest part of the Kadonosawa Fauna).
The strontium isotope ratio (87Sr/86Sr) of the shell of Crenomytilus grayanus (Dunker) from the Yamanouchi Member of the Akeyo Formation, Mizunami Group in Toki-cho, Mizunami City, Gifu Prefecture, Japan is determined. The strontium age suggests that the Crenomytilus grayanus-bearing horizon has been deposited at 17.8 ± 0.3 Ma. Therefore, the occurrence of C. grayanus in central Japan may have been related to the Early Miocene global cooling event (Mi1b) at 17.8 Ma.
Recently, a PhD candidate, Jessica N. Tashman, at Kent State University conducted a study of grooming behavior as demonstrated in fossil crabs (Tashman et al., 2008). She recognized areas on the carapace of the crabs that could be cleaned by the animals and areas that were beyond their reach. The study helped recognize living and post-mortem infestations of epibionts. The study would not have been possible without the contribution of extremely well-preserved fossil crabs (Fig. 1) made available by Bruce Thiel from Portland, Oregon. The provenance of the specimens was well documented, and the meticulous preparation permitted careful documentation of the biotic interactions. To assure long-term care of the specimens, referred to as T185 and T246 in Thiel’s collection and in Tashman et al. (2008), the material has been deposited in the Rice Northwest Museum of Rocks and Minerals, Hillsboro, Oregon, with catalogue numbers RM8623 and RM8624, respectively.
Orithyia eikii, new species discovered from the Lower Miocene Mizunami Group of Japan, constitutes the first reported occurrence of Orithyiidae Dana, 1852 in 1852–1853 in the fossil record. The new species superficially resembles Orithyia sinica (Linnaeus, 1771), the sole included extant species of the family and genus from East Asia, but it differs in having only one spine on the posterolateral margin of the carapace. The discovery of this species extends the geologic range for the family and genus back to the Early Miocene.
The detailed preparation of remains of the paguroid Eocalcinus eocenicus Vía Boada, 1959, from the middle Eocene of Central Catalonia, has revealed for the first time the, hitherto unknown, right chela of this hermit crab. A diagnosis is provided herein. Based on the new data, Eocalcinus eocenicus is herein transferred to the family Calcinidae.
The Lower Miocene Togari and Yamanouchi members (ca 18 Ma) of the Akeyo Formation, Mizunami Group, were exposed at the construction site of the Togari-Tsukiyoshi Road in Akeyo-cho, Mizunami City, central Japan. Their lithologies are described. The Togari Member, 25 m thick, overlies the Toki Granite and consists mainly of tuffaceous sandstone with three tuff layers including Tu-tuff. The middle part of the member contains lenticular shell lens of Crassostrea. The lower part of the Yamanouchi Member consists mainly of tuffaceous silty sandstone. Pinniped fossils occur in the lowermost part of the member (20 cm above the boundary between Togari and Yamanouchi members). Measurements of the anisotropy of magnetic susceptibility (AMS) suggest that a paleocurrent direction was NE–SW or NW–SE with an unknown upstream direction for the stratigraphic horizon just above the Togari/Yamanouchi boundary.
A pinniped fossil was found at the construction site of the Togari-Tsukiyoshi City Road in Akeyo-cho, Mizunami City, Gifu Prefecture, Japan in September 2020. We briefly report this new discovery of a partial skeletal bones belonging to a single individual (MFM18009), which was recovered from the lowermost part of the Yamanouchi Member of the Akeyo Formation, the Mizunami Group (lower Miocene: ca 18 Ma). MFM18009 is consisted from a complete skull, distal half of the left mandible, the atlas, distal half of the left humerus, proximal half of the left ulna, the third metacarpus, thoracic vertebrae and ribs. MFM18009 seems to belong in the Pteronarctos-Pacificotaria species complex of pinnipediforms, and is provisionally identified as Enaliarctine genus and species undetermined.