Rhinocerotid fossils from the lower upper Miocene Namurungule and Nakali Formations, northern Kenya, are described. These materials reveal the following diagnostic characters of Chilotheridium pattersoni: a strongly constricted protocone with a flattened lingual wall, a hypocone groove, a developed crochet, and an antecrochet curved toward the entrance of the medisinus. Specimens previously described from the Namurungule Formation as rhinocerotids are re-identified as C. pattersoni. The Nakali Formation specimens presented in this study are the first discovery of C. pattersoni from this locality. In addition, deciduous teeth of C. pattersoni, which were unknown previously, are reported for the first time. This discovery of C. pattersoni extends its temporal range to the early late Miocene.

Morphogenetic mechanisms in modern Scleractinia provide insights into the habitats and growth forms of corals living in different environmental conditions. Scleractinian morphogenesis has been studied primarily in relation to extrinsic (e.g. environmental) factors, irrespective of specific regularities in budding and their impacts on growth forms. Morphogenesis in colonial dendrophylliids can be modelled by taking these developmental traits into account, so as to understand how intrinsic developmental factors affect morphologies resulting from colonial growth. We used a simple, voxel-based program to simulate the morphogenesis of dendrophylliid corals. Three parameters (budding orientation, inclination of budding, and interval of budding) were adopted to simulate a range of colonial growth forms, regardless of whether the forms exist in nature or not. The regularity of budding was fully taken into account, and various colonial morphologies were gained, even under strict regularity. The regulation of two of the parameters (inclination of budding and budding interval) gives rise to two distinct types of morphologies (branching and massive forms) that are represented by the extant taxa Dendrophyllia arbuscula and Tubastraea coccinea, respectively. This suggests that the growth forms of individual dendrophylliid colonies vary according to habitat conditions, and that they can be simulated by modifying only a few parameters, even given rigid developmental constraints on budding.

The megamouth shark (Lamniformes, Megachasmidae) is one of four extant planktivorous elasmobranch lineages, but its fossil record is quite limited. In the present study, we report a new discovery of a rare megachasmid shark fossil from the late Miocene—early Pleistocene interval of Okinawa Island, Japan. To date, this specimen represents the only reliable record of a megachasmid fossil from Asia.

Well preserved specimens of two ophiuroid species, both assignable to an unknown family (formerly Ophiolepididae) and here placed in Ophiomusium and Ophiosphalma have been recovered from lower Miocene deep-sea formations in Japan. The material consists of an assemblage of over 75 articulated body fossils and numerous semiarticulated arm segments from the lower Miocene Oi Formation (Ichishi Group), Mie Prefecture, central Japan, identified as the extant species Ophiomusium lymani Wyville Thomson and a single articulated body fossil assigned to the extant Ophiosphalma cancellata (Lyman) from the lower Miocene Shida Formation (Oigawa Group), Shizuoka Prefecture, central Japan. These occurrences constitute the oldest fossil record of these present-day brittlestar species. The latter is the first fossil record for the genus Ophiosphalma. The new material documents that the closely related genera Ophiomusium and Ophiosphalma had already diverged by the early Miocene. Furthermore our findings suggest that the ancient Ophiomusium lymani and Ophiosphalma cancellata inhabited the same upper bathyal environment as their Recent counterparts.

The taxonomy, biostratigraphy and paleobiogeographic origin of Churkites, an Early Triassic acuteventered arctoceratid ammonoid genus, are reported based on carefully controlled bed-by-bed sampling of several sections in South Primorye, Russian Far East. Churkites syaskoi is herein regarded as a synonym of the type species, C. egregius, which was described from the upper Smithian (loewr Olenekian) Anasibirites Zone of Russia. C. egregius is relatively abundant in sandstone laminae in the laminated mudstone beds of distal turbidites, but rare in the sandstone beds of relatively proximal turbidites. In contrast, Anasibirites is abundant in the sandstone beds, but very rare in the mudstone beds. This disparity in occurrence makes a precise biostratigraphic correlation difficult for the upper Smithian Anasibirites Zone in the mudstone facies, but C. egregius makes it possible to correlate the zone in the mudstone facies. The different modes of occurrence among ammonoid taxa strongly suggest that they either were preserved by different taphonomic processes or had different habitats. Churkites most likely evolved from Arctoceras tuberculatum on the eastern side of the Panthalassa during the middle Smithian and then crossed the Panthalassa and gave rise to C. egregius on the western side of the Panthalassa during the late Smithian. This westward dispersal across the Panthalassa was likely aided by westward equatorial currents as well as by stepping stones provided by the shallow waters around reefs and island terranes.

The evolution of paleoecosystems was often accompanied by the expansion of ecological niches; organismal habitats extended from the sediment surface to the water column, and then to the interior part of the sediment. A major step in ecosystem innovation was recorded in the macrobiota of the upper Doushantuo Formation during the middle-late Ediacaran Period, including the Miaohe biota from western Hubei and the Wenghui biota from northeastern Guizhou, in the Yangtze Block, South China. The macrobiota was dominated by branching and unbranching macroalgae, with abundant metazoans (including worms or vermiform animals, trilobozoans, poriferans, and medusiform animals) and ichnofossils. They lived in a warm and calm tropical ocean, with plentiful sunlight, oxygen, and nutrients. The habitats of the organisms can be subdivided into three layers of morphology and paleoecology: the epibenthic layer, the erect-benthic layer, and the plankton layer. In the case of the epibenthic and erect-benthic layers, the organisms lived on the depositional surface, or were fixed on the seafloor; in the plankton layer, the organisms floated in the water column or on the water surface. In middle-late Ediacaran macroorganism paleoecosystems, the following changes occurred: diversification, the intensification of competition between organisms, a reinforcement of the ability of organisms to change their surroundings, and the effective conversion of bioenergy. The macroorganism paleoecosystem was a key transition in the establishment of a complicated and multilayered ecological pyramid and increasing atmospheric oxygen, and a prelude to the Cambrian explosion.

A new specimen of Paleoparadoxia found from a marine lower Miocene deposit in the Chikubetsu area, Hokkaido, Japan, is described. The material consists of a distal part of the scapula, proximal end of the humerus from the right side, as well as a fragmentary rib, preserved in a float of calcareous fine sandstone. The specimen is referred to the order Desmostylia and subsequently to the genus Paleoparadoxia sp. The well preserved shoulder girdle of this specimen provides the first detailed morphology of this anatomical region in Paleoparadoxia. We compared the specimen with a wide range of desmostylid samples to reveal new diagnostic characters for the genus, such as the greater tubercle extending toward the proximal side above the head and the distinct lesser tubercle located on the medial side, projected medially. The lower Miocene Sankebetsu Formation outcrops in the area where the float was found, and the lithology and associated fossil fauna of the float indicate that it was derived from there. The fossil pollen assemblages and molluscs found in the formation indicate that it was deposited under cool to temperate conditions. The new specimen thus suggests that Paleoparadoxia had inhabited a cool environment in addition to warm areas, as suggested in previous studies. The published age estimate of the formation places the present specimen between 23.8±1.5 and 20.6±1.0 Ma. This represents the oldest record of the genus Paleoparadoxia, exceeding the previous record of ca. 19 Ma for a specimen found from the Chichibu Basin, and nearly matches the oldest record of Paleoparadoxiinae in the Northwestern Pacific. This indicates that the ages of the oldest occurrences of basal and derived paleoparadoxiines overlapped (i.e., Archaeoparadoxia from the Northeastern Pacific Region and Paleoparadoxia from the Northwestern Pacific, respectively). It is also likely that the geographic range of Paleoparadoxiinae had already expanded from the Northeast Pacific to the Northwest Pacific in the early stage of their evolution.