||Shigeta, Y., Maeda, H., and Sakai, T., Dimorphism in the early Cenomanian (Late Cretaceous) ammonite Parajaubertella, Paleontological Research, 27, 2023.01, Ontogenetic development of ornamentation and whorl geometry of the Cretaceous ammonites Parajaubertella kawakitana and P. zizoh are studied based on well-preserved specimens collected from the lower Cenomanian in the Horokanai area, Hokkaido, Japan. Our results indicate that their comparably sized immature stages share identical ornamentation and shell morphology, while the size of their adult shells is discretely bimodal. They also share the same stratigraphic ranges in the lower Cenomanian and have overlapping geographic distributions in Northwest Pacific region, and lastly, they co-occur in the same concretions. This evidence strongly suggests that the two taxa should be considered as dimorphs, microconch and macroconch of a single species, which is herein described as P. kawakitana..
||Shigeta, Y. and Maeda, H., Late Maastrichtian (latest Cretaceous) ammonoids from the Naiba area, southern Sakhalin, Russian Far East, Paleontological Research, 26, 2022.12, Six taxa of early late Maastrichtian (Late Cretaceous) ammonoids are reported from the Krasnoyarka Formation of the Yezo Group in the Naiba area, southern Sakhalin, Russian Far East. These taxa are grouped into “immigrant species”, i.e., those that migrated from other regions (Pachydiscus subcompressus, Anagaudryceras mikobokense, Gaudryceras seymouriense and Zelandites varuna) and “indigenous species” with a North Pacific distribution (Anagaudryceras matsumotoi). It is unclear to which group Tetragonites sp. belongs. Zelandites varuna and G. seymouriense occur in both the lower upper Maastrichtian as well as the upper lower Maastrichtian in southern Sakhalin, but they have never been found in the middle Maastrichtian. Appearance of the two species in the cold-water regions, i.e., North Pacific and Antarctic, as well as intermediate southern mid-latitudes regions suggests that cooling events occurred during the late early and early late Maastrichtian in the Northwest Pacific region. Their disappearance during the middle Maastrichtian may indicate that the Northwest Pacific region was affected by the greenhouse Middle Maastrichtian Event (MME). This hypothesis suggests that the influx (e.g. P. subcompressus and A. mikobokense) and reappearance (e.g. Z. varuna and G. seymouriense) of many immigrant species into the Northwest Pacific region during late Maastrichtian time may have been associated with the post-MME cooling..
||Different preservational states of Lower Jurassic hildoceratid ammonoids by lithofacies.
||Maekawa, T., Kiyokawa, S., Maeda, H., Tanaka, G., Costa, J.E.F., and Freitas, A.T., First report of early Permian albaillellarian radiolarians from East Timor, Paleontological Research, 10.2517/2020PR009, 25, 1, 32-40, 2021.01, Two early Permian radiolarians, Pseudoalbaillella postscalprata Ishiga, 1983 and Pseudoalbaillella sakmarensis (Kozur, 1981), are described from a calcareous nodule of the Permian sedimentary rocks distributed in north-central East Timor. This is a first report of age-diagnostic Permian radiolarians from East Timor and provides a potential source of well-preserved radiolarians from the Permian sedimentary rocks..
||Oyama, N. and Maeda, H., Madygella fumioi sp. nov. from the Upper Triassic Mine Group, southwest Japan: the oldest record of a sawfly (Hymenoptera: Symphyta) in East Asia., Paleontological Research, 10.2517/2019PR005, 24, 1, 64-71, 2020.01, A primitive sawfly, Madygella humioi sp. nov., belonging to the family Xyelidae (Hymenoptera: Symphyta), is a newly described species from the Upper Triassic Mine Group, Yamaguchi Prefecture, southwest Japan. The new species differs from the other five Madygella species in having a shorter cell length of 1r plus 2r than that of 3r+4r and a lower cell height of 3r+4r than 2r plus pterostigma in a forewing. To date, this is the oldest fossil record of sawflies in East Asia. Regarding the genus Madygella, this is the first example found from a region other than Kyrgyz Republic. This discovery provides an insight into the early evolution of the order Hymenoptera and suggests a widespread distribution of the pioneering genus Madygella during the Triassic period..
||Stratigraphy and fossil assemblages of the Triassic Mine Group and Jurassic Toyora Group in western Yamaguchi Prefecture.
||Tanaka, G., Miyake, Y., Ono, T., Yuan, A.H., Ichida, M., Maeda, H., and Crasquin, S., Early Permian (Cisuralian) ostracods from Japan: characteristic ostracod assemblage from a seamount of the Panthalassic Ocean, Zootaxa, https://doi.org/10.11646/zootaxa.45151.1, 4515, 1-67, 2018.10, Silicified ostracods were recovered from Cisuralian micritic limestones of the Ryozensan Limestone Formation from the
southwestern part of Ryozensan Mountain, Taga City located in Shiga Prefecture, Central Japan. Twenty-seven species
belonging to 19 genera were obtained, of which six species are new and are described here: Bairdia tagaensis Tanaka sp.
nov., Bairdiacypris ikeyanoriyukii Tanaka sp. nov., Kellettina noriyukii Tanaka sp. nov., Microcheilinella shigensis Tanaka
sp. nov., Oliganisus ryozensannensis Tanaka sp. nov., and Pustulobairdia ohmiensis Tanaka sp. nov. Some Palaeozoic limestone localities in Japan cap greenstones and are surrounded by younger cherts (such as Mino Terrane of this study). They represent a characteristic reef and reef-slope environment around a seamount surrounded by deep sea ocean floor. This result is concordant with the ostracod assemblage. After this report, a Panthalassan ostracod fauna could be defined for the Cisuralian..
||Tanaka Gengo, Parker, A.R., Hasegawa Yoshikazu, Siveter, D.J., Yamamoto Ryoichi, Miyashita Kiyoshi, Takahashi Yuichi, Ito Shosuke, Wakamatsu Kazumasa, Mukuda Takao, Matsuura Marie, Tomikawa Ko, Furutani Masumi, Suzuki Kayo, Maeda Haruyoshi, Mineralized rods and cones suggest colour vision in a 300 Myr-old fossil fish., Nature Communications, 10.1038/ncomms6920, 5, 1-6, 2014.12, Vision, which consists of an optical system, receptors and image-processing capacity, has existed for at least 520 Myr. Except for the optical system, as in the calcified lenses of trilobite and ostracod arthropods, other parts of the visual system are not usually preserved in the fossil record, because the soft tissue of the eye and the brain decay rapidly after death, such as within 64 days and 11 days, respectively. The Upper Carboniferous Hamilton Formation (300 Myr) in Kansas, USA, yields exceptionally well-preserved animal fossils in an estuarine depositional setting. Here we show that the original colour, shape and putative presence of eumelanin have been preserved in the acanthodii fish Acanthodes bridgei. We also report onthe tissues of its eye, which provides the first record of mineralized rods and cones in a fossiland indicates that this 300 Myr-old fish likely possessed colour vision..
||Misaki Akhiro, Maeda Haruyoshi, Kumae Taro, Ichida Masahiro, Commensal anomiid bivalves on Late Cretaceous heteromorph ammonites from southwest Japan, Palaeontology, 10.1111/pala.12050, 57, 77-95, 2014.02, The heteromorph ammonite Pravitoceras sigmoidale from the Upper Cretaceous Seidan Formation (Izumi Group) in south-west Japan is frequently encrusted by sessile anomiid bivalves. Fossils of P. sigmoidale with anomiids are often concentrated at the top of or just above turbidite sandstones. Projecting retroversal hooks and apertures of P. sigmoidale are usually intact, and some individuals are associated with jaw apparatuses near apertures. Anomiids are found on both sides and ventral peripheries of P. sigmoidale conchs, attached predominantly to body chambers. These modes of occurrence suggest that the encrustation by anomiids occurred not on post-mortem floating or sunken carcasses but on live conchs and that these organisms were rapidly buried by turbidity current deposits shortly after death. Attachment to both flanks and ventral peripheries of the retroversal hooks may indicate that at least adult individuals of P. sigmoidale did not lie on the sea floor and did not drag their body chambers. It is suggested that fully mature individuals of this ammonite species lived for a long period of time after having formed the retroversal hook because a few generations of anomiids have colonized a single body chamber. Such colonization by anomiids is also observed on Didymoceras awajiense, which is considered to be the closely related ancestral species of P. sigmoidale. This anomiid–heteromorph ammonite commensal relationship might continue to persist in descendants during the course of evolution of these heteromorph ammonites..
||Tsujino Yasuyuki, Shigeta Yasunari, Maeda Haruyoshi, Komatsu Toshifumi, Kusuhashi Nao, Late Triassic ammonoid Sirenites from the Sabudani Formation in Tokushima, Southwest Japan, and its biostratigraphic and paleobiogeographic implications., Island Arc, 22, 10.1111/iar.12050, 549-561, 2013.02, Discovery of Sirenites senticosus (Dittmar) in the upper part of the Sabudani Formation of the Kurosegawa Belt, Kito area, Tokushima Prefecture, Japan, establishes a late Early Carnian age for this part of the stratigraphic unit. Because S. senticosus was mainly distributed in the Tethyan region, its occurrence provides evidence that Late Triassic ammonoids of Japan had strong affinities with those of the Tethyan faunas. This finding clearly differs from the biogeographic distribution of contemporary bivalves in the region, which are referred to as the Kochigatani bivalve faunas, and show strong affinities to faunas of the Boreal region..
||Yamaji Atsushi, Maeda Haruyoshi, Determination of 2D strain from a fragmented single ammonoid, Island Arc, 22, 126-132, 2013.02, Planispiral ammonoids are used for strain analysis, as the pre-strain shapes of their shells are thought to be approximated by logarithmic spirals. Comparison of the preand observed post-strain spirals determines the strain.We show in this short note that the Rf /f strain analysis is applicable to the ammonoids, where the interspaces of a shell are used as strain markers. Unlike the previous methods that assumed the spiral, the present technique can use fragmented shells, provided that they have at least half windings and clear limbs. A strain ellipse and its 95% confidence limit were determined by the hyperbolic vector mean method from the ellipses that were fitted to the interspaces of a fragmented, deformed ammonite from the Kitakami Massif, Northeast Japan, as a worked problem for the present technique..
||Fujino Shigehiro, Maeda Haruyoshi, Environmental changes and shallow marine fossil bivalve assemblages of the Lower Cretaceous Miyako Group, NE Japan, Journal of Asian Earth Sciences, 10.1016/j.jseaes.2012.12.13., 64, 168-179, 2013.01, We reconstructed the environmental changes recorded in the Lower Cretaceous Miyako Group via facies analysis and delineated the relationship between depositional facies and the occurrence of diverse marine invertebrate macrofossils. The Miyako Group consists of deposits from alluvial bay-head delta, bayhead delta front, central bay, and lower shoreface to inner shelf depositional settings. Fossil bivalve assemblages responded to shifts in these sedimentary environments. We defined three fossil bivalve assemblages from the central bay and lower shoreface to inner shelf deposits. The assemblages in the inner shelf and central bay deposits are clearly different, even though they occur within similar depositional facies. This contrast in assemblages results from environmental differences between closed and open settings; this interpretation is supported by the occurrence of stenohaline crinoids. We defined a fourth bivalve assemblage in a tsunami deposit intercalated within the bay-head delta front deposits. It consists of polygenic allochthonous shells, some that were derived from an estuarine environment or the shallow seafloor and others that were torn from small reefs..
||Tanaka Gengo, Matsushima Yoshiaki, Maeda Haruyoshi, Holocoene ostracods from the borehole core at Oppama Park, Yokosuka City, Kanagawa Prefecture, central Japan: Paleoenvironmental analysis and the discovery of a fossil ostracod with three- dimensionally preserved soft parts, Paleontological Research, 16, 1, 1-18, 2012.04.
||Maeda Haruyoshi, Tanaka Gengo, Shimobayashi Norimasa, Ohno Terufumi, Matsuoka Hiroshige, Cambrian Orsten lagerstätte from the Alum Shale Formation: fecal pellets as a probable source of phosphatic preservation, Palaios, 10.2110/palo.2010.p10-042r, 26, 225-231, 2011.04, The Furongian Orsten-type fossil Lagerstätte in the Alum Shale Formation of Sweden is an extraordinary deposit known for its detailed, three-dimensional preservation of the soft parts of small animal carcasses which have been replaced by calcium phosphate and occur in organic-rich nodular limestone. The exact cause and mechanism of this unusual fossil preservation, however, particularly the source of phosphorus, which plays a key role, remains unknown. Detailed observation in the Agnostus
pisiformis Zone in the Backeborg section (Kinnekulle district) reveals that the phosphatocopine crustaceans showing soft-part preservation occur
only in a few thin ( 3 cm) layers containing abundant fecal pellets (pellet beds). Development of cross lamination suggests that the pellet beds were formed by low density sediment-gravity flow. Orsten-type preservation has been attributed to high phosphate levels in global marine waters during the Cambrian period; however, wavelength-dispersive X-ray and Xray diffractometry analyses reveal that the Orsten limestones and surrounding shale were generally poor in phosphorus, which was mostly concentrated in the fecal pellets. The small animal carcasses preserved in such deposits were phosphatized during early diagenesis owing to the high local phosphorus levels of the accumulated fecal pellets. Searches for such cesspool-type preservation may yield further discoveries of Orsten-type fossil Lagerstätten in other strata of various ages..
||Misaki Akhiro, Maeda Haruyoshi, Stratigraphy of the mid- to upper Cretaceous System in the Aridagawa area, Wakayama, southwest Japan, Island Arc, 10.1111/j.1440-1738.2010.00727.x, 19, 517-529, 2010.06, The litho- and biostratigraphy of the mid- to upper-Cretaceous System around the Yagumaike Pond in the Aridagawa area, Wakayama, Southwest Japan, were investigated. Many Middle to Late Albian megafossils were found in the strata of a block bounded by faults. It was also revealed that the Upper Cretaceous System of other blocks ranges from the Middle Turonian to Santonian. The Albian megafossil assemblage contains few benthic organisms, in contrast with the abundance of nektons found (e.g. cephalopods). Sedimentological observations of the mudstone profiles also indicate that scarcely or weakly bioturbated, well-laminated mudstone is dominant among the Albian deposits. These results suggest deposition of the Albian mudstone under a dysaerobic to anoxic environment. It is comparable to the extended oceanic anoxia (OAEs) in mid-Cretaceous time. Albian deposits with similar characteristics are also known to exist in Shikoku, Southwest Japan. A wide sedimentary basin that was directly affected by global environmental events, such as OAEs, seemed to be formed on the Chichibu Belt in the Albian. The Upper Cretaceous strata in the study area are extremely thin, similar to the coeval deposits on the Chichibu Belt in Shikoku. It is suggested that the sedimentation rate in the sedimentary basin on the Chichibu Belt was extremely low during early Late Cretaceous time..
||Tanaka Gengo, Taniuchi, H., Maeda Haruyoshi, Nomura Shin'ichi, Original structural color preserved in an ancient leaf beetle, Geology, 38, 127-130, 2010.03.
||Maeda Haruyoshi, Kumagae Taro, Matsuoka Hiroshige, Yamazaki Yosuke, Taphonomy of large Canadoceras (ammonoid) shells in the Upper Cretaceous Series in South Sakhalin, Russia, Paleontological Research, 10.2517/1342-8144-14.1.056, 14, 1, 56-68, 2010.03, Based on materials from the Krasnoyarka Formation in the Naiba area in south Sakhalin, Russia, taphonomic histories of a large Campanian ammonoid, Canadoceras kossmati Matsumoto, 1954, were closely investigated. Large Canadoceras shells exceeding 30 cm in diameter are usually embedded horizontally and solitarily in muddy sandstone. Athin, lenticular calcareous concretion envelopes the shell (=envelope concretion). Their body chambers are mostly lost. The inner whorls comprising the center of the umbilicus completely disappear without exception, and only two or three outer whorls are preserved. The body and air chambers are somewhat compressed by compaction and are filled with sediments. Phycosiphon burrows are common not only in open body chambers but also in inner air chambers, which were originally closed. These observations suggest that the thin-shelled inner whorls and organic-rich siphuncular tubes degraded before final burial of the shell, and sediment infilling to the inside of the chambers followed. The early loss of inner whorls and siphuncular tubes gave rise to “draft-through currents.” The continuous supply of oxygen and nutrients by the draft-through currents supported the Phycosiphon producers in the inner air chambers. Compared with other calcareous concretions containing intact fossils, values of minus-cement porosity (MCP) remain relatively low (63–74%) and vary by areas even in the same envelope concretion. This indicates that the envelope concretions were cemented under a progressive increase of compaction during the later diagenetic stage. The formation of the envelope concretion appears to be a long-term phenomenon. Various events at different stages have been overprinted in a single large ammonoid fossil..
||Nishimura Tomohiro, Maeda Haruyoshi, Tanaka Gengo, Ohno Terufumi, Taxonomic evaluation of various morphological characters in the Late Cretaceous desmoceratine polyphyletic genus "Damesites" from the Yezo Group in Hokkaido and Sakhalin, Paleontological Research, 14, 1, 33-55, 2010.03.
||Tsujino Takumi, Maeda Haruyoshi, Maeda Yoko, Taphonomic processes in diatomaceous laminites of the Pleistocene Shiobara Group (caldera-fill, lacustrine), Northeastern Japan, Paleontological Research, 13, 3, 213-229, 2009.09, Diatomaceous laminites of the Pleistocene Shiobara Group (caldera fill), located in the volcanic front of the Northeastern Japan Arc, are the profundal facies of
palaeo-Shiobara Lake. The laminites are subdivided into five types of laminite: clastic (Type A), diatom-preserved (Type B), porcelainised (Type C), double (Type D) and reversal (Type E). These varieties are mostly induced by lithification, indebted to localised hydrothermal alteration represented as diatom frustules’ transformation from opal-A to opal-CT. Type B laminite alters to Type C, Type D and finally Type E laminites, in a progress order. As alteration is advancing, the rock become more consolidated, and lamina texture changes from porous to massive one. Exceptionally, Type A laminite, composed of grey terrigenous lamina, shows few changes, because
of poor content of diatom frustules. Type B laminite, composed of porous white diatomaceous lamina and grey terrigenous lamina, is replaced by Type C laminite, composed of tightly-packed opal-CT lepispheres. Type D laminite is represented as a set of four laminae grey, white-1, black, and white-2, in upward sequence. The black laminae result from the additional reprecipitation within the white laminae, and laterally fade. Type E laminite is the last stage of alternation series of the laminites in Shiobara and consists of thin couplets of grey and black laminae. White laminae completely alters to black laminae. Whereas Type A and B laminites is widely distributed in the basin, Type C is distributed in the restricted area. Type D and E laminites are found at only one quarry which yields the exceptionally-well preserved megafossils; mice, frogs, feather, fishes, and insects. These laminite variations are likely derived from alteration by hydrothermal water associated with an caldera..
||Matsunaga Takeshi, Maeda Haruyoshi, Shigeta Yasunari, Hasegawa Koji, Nomura Shin'ichi, Nishimura Tomohiro, First discovery of Pravitoceras sigmoidale Yabe from the Yezo Supergroup in Hokkaido, Japan, Paleontological Research, 12, 4, 309-319, 2008.12.
||Allison P.A., Maeda Haruyoshi, Tsujino Takumi, Maeda Yoko, Exceptional preservation within Pleistocene lacustrine sediments of Shiobara, Japan, Palaios, 23, 4, 260-266, 2008.08.
||Maeda Haruyoshi, Mapes, R.H., Mapes, G., Taphononic features of a Lower Permian beached cephalopod assemblage from central Texas, Palaios, 18, 4, 5, 421-434, 2003.10.
||Maeda Haruyoshi, Dimorphism of two late Cretaceous false-puzosiine ammonites, Yokoyamaoceras Wright and Matsumoto, 1954 and Neopuzosia Matsumoto, 1954, Trans. Proc. Palaeont. Soc. Japan, N.S., 169, 97-128, 1993.06.
||Maeda Haruyoshi, Sheltered preservation: a peculiar mode of ammonite occurrence in the Cretaceous Yezo Group, Hokkaido, north Japan, Lethaia, 24, 1, 69-82, 1991.03.
||Maeda Haruyoshi, Taphonomy of ammonites from the Cretaceous Yezo Group in the Tappu area, northwestern Hokkaido, Japan, Trans. Proc. Palaeont. Soc. Japan, N.S., 148, 285-305, 1987.12.