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A thylacocephalan fauna from the upper Olenekian (Lower Triassic) Osawa Formation in the South Kitakami Belt, Northeast Japan, is described. The fauna comprises three species belonging to three genera: Ankitokazocaris bandoi Ehiro and Kato sp. nov., Kitakamicaris utatsuensis Ehiro and Kato gen. et sp. nov., and Ostenocaris sp. This is the first report of fossils belonging to the class Thylacocephala from Japan, and it expands their paleogeographic distribution. As almost all genera of Thylacocephala inhabited low-latitude areas in each relevant geological time, their occurrence from the Osawa Formation supports previous opinions that the South Kitakami Belt was located in the equatorial region during the Triassic.
It has been experimentally shown that the shell morphology of concavo-convex productide brachiopods has the potential to generate passive flows for feeding. However, there still remains the problem of how the presence of internal soft parts influences the course and pattern of the flows. To clarify the effect of soft parts, we performed additional experiments of fluid visualisation using a flow tank and a transparent, polyhedral model with supposed soft parts in a postero-median region. Regardless of the ambient flow directions, the experimental results showed that inflows through ear gapes turned into symmetrical vortices inside the model. The soft parts altered the course of internal flows and interfered with the vortices entering the median region. Therefore, stepwise inflows pushed the precedent vortices forward as the rotational speed decreased. As a result, the slower vortices aligned with the brachial ridges on which the lophophore was arranged. Morphologically, productide brachial ridges tend to lie in the antero-lateral corners of the dorsal disc. The rectifying effect by means of soft parts, though consequential, would enable productides to sieve food particles from gentle vortices rather than from swift vortices just after the inflow through the ear gapes.
Two species of Darriwilian (late Middle Ordovician) nautiloid cephalopods are described from the Wunbye Formation and its equivalent strata in the Shan Plateau of Myanmar (Sibumasu Block). They are the orthocerid Sibumasuoceras langkawiense (Kobayashi) and the discosorid Tasmanoceras sp. First, Sibumasuoceras is proposed for a new genus of the cayutoceratin pseudorthoceratids. Sibumasuoceras langkawiense [originally Ormoceras langkawiense, the type species of the genus] was previously assigned either to the Actinocerida or the Discosorida. However, the present investigations reveal that it possesses thin connecting rings and differentiated endosiphuncular deposits and lacks a detailed endosiphuncular canal system, all suggestive of a relationship to the Orthocerida. Sibumasuoceras is known to occur so far from Malaysia and Myanmar of the Sibumasu Block, which was part of northern Gondwana during the early Palaeozoic. Second, the rare genus Tasmanoceras, which was previously known only in Tasmania, is confirmed in Southeast Asia for the first time; this implies an Ordovician marine biotic linkage between Sibumasu and Tasmania over northern Gondwana.
Turbo (Marmarostoma) matsuzakiensis Tomida and Kadota with an in situ operculum was found in limestone within the tuffaceous sandstone of the middle Miocene Yugashima Group, at Shikura, Shizuoka Prefecture, Japan. The presence of an operculum on T. (M.) matsuzakiensis Tomida and Kadota is confirmed and described in this paper, and demonstrates the autochthonous occurrence of the fossil.
Based upon large cerithiform gastropod specimens from the middle Miocene beds of Java, Indonesia and the Philippines, a new genus and new species, Megistocerithium magoi, is described herein. Ten fragmentary specimens from the lower and upper Miocene beds of the Philippines are tentatively referred to this species. M. magoi Kase sp. nov. is amongst the largest fossil cerithioidean gastropods (except for Turritellidae). It was a dweller in intertidal sandy mudflats, probably in close proximity to mangrove forests. No species considered to be congeneric with this species have been found in the Cenozoic. On the other hand, M. magoi Kase gen. et sp. nov. shares apertural characters with the Middle Jurassic species Eustoma tuberculosa, the type species of a genus belonging to the yet to be well-recognized family Eustomatidae. M. magoi Kase gen.et sp. nov. is possibly a relict of the Mesozoic Eustomatidae. It is assumed to have been a grazer on mangrove litter like the potamidid genera Terebralia and Telescopium in modern mangrove swamps.
The Early Triassic conodonts Eurygnathodus costatus Staesche, E. hamadai (Koike), Neospathodus cristagalli (Huckriede), and Ns. pakistanensis Sweet are newly reported from the upper part of the Lang Son Formation in Lang Son City, northeastern Vietnam. This association and particularly E. costatus and E. hamadai indicate the lower Smithian (lower lower Olenekian). Thus, the geological age of the upper part of the Lang Son Formation ranges from Induan to early Olenekian, and the stage boundary lies within the upper part of the formation.
A trigonid of a lower molar of a primitive, large hippopotamus from the upper lower Miocene of Mfwangano Island in southwestern Kenya is described. The molar trigonid is similar in size to that of living hippopotamuses, and is comparable in morphology to that of kenyapotamine hippopotamids (Mammalia, Cetartiodactyla) in having a brachyodont crown, bunodont cusps, an M-like structure on the distal trigonid wall, a single-ridged premetacristid, and a buccolingually bifurcate mesial root, and in lacking a paraconid. On the basis of its size and morphology, the specimen appears to be assignable to Kulutherium, which is a putative kenyapotamine previously known from the upper lower Miocene of Kenya and is so far represented only by the upper dentition. The present specimen provides additional evidence that a hippopotamus-sized, large hippopotamid was already living during the early Miocene. If it proves to be Kulutherium, it provides additional evidence that Kulutherium should be assigned to the Kenyapotaminae.
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