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Four skull specimens (MPC-D 100/537,100/538,100/539 and100/540) of Protoceratopsidae from the Upper Cretaceous in Udyn Sayr, Mongolia are described, and their ontogenetic stage and expression of sexual dimorphism are estimated. These specimens are identified as Protoceratops andrewsi (MPC-D 100/537, 100/539), P. cf. andrewsi (MPC-D 100/538), and Protoceratops sp. (MPC-D 100/540), respectively. MPC-D 100/537 and 100/539 are attributed to subadult “female” and MPC-D 100/538 to subadult “male”. MPC-D 100/540 is adult with unknown sex.
Based on the frill morphologies, the Udyn Sayr specimens are classified into three types: type 1 (MPC-D 100/539), well developed ridge on the lateral surface of the squamosal; posteriorly projected posterior margin of the squamosal; type 2 (MPC-D 100/537), posteriorly rounded posterior margin of the squamosal; developed ridge on the posterior margin of the parietal; and type 3 (MPC-D 100/540), large size; posteriorly curved posterior margin of the squamosal; the rugose surface texture on the dorsal side of parietal. MPC-D 100/538 could not be categorized because the specimen's frill is not preserved. These frill morphologies differ from those of Protoceratops from the Djadokhta Formation in the adjacent dinosaur locality Tugrikin Shire. The morphological differences among the Udyn Sayr specimens may indicate intraspecific variation of Protoceratops.
Sponge spicules were extracted from dolostone in the lower part of the Neoproterozoic Doushantuo Formation in the Yangtze Gorges area (South China), which has an age of ∼630 million years. The spicules appear to occur in at least two morphologies; monaxons and triaxons with rays in various planes. Energy dispersive spectrometer (EDS) analysis indicates that the spicules are siliceous. Furthermore, closely spaced occurrences of hexactinellid sponge spicules are observed in thin sections. This study represents the first discovery of siliceous sponges from the well known standard section of the Neoproterozoic in South China, and also confirms the stratigraphie extension of the most primitive multicellular animal before the Gaskiers glaciation.
Two ammonoids of the subfamily Gabbioceratinae, Obataceras manjiense gen. et sp. nov. and Tanabeceras pombetsense gen. et sp. nov., are described from the Upper Albian of Hokkaido, Japan. The Gabbioceratinae evolved and radiated mainly in the Mediterranean area during Late Aptian to Middle Albian times, but thereafter disappeared from the region. The occurrences of Gabbioceratinae in Hokkaido suggest that their geographical distribution was extended to the Northwest Pacific before the Late Albian, where they then flourished from Late Albian to Cenomanian time.
Late Early Carboniferous (late Visean) to late Middle Permian (Capitanian) foraminifers have been recovered from limestone blocks and fragments contained in the Tsunemori Formation in Yamaguchi Prefecture, Southwest Japan, which is unconformably overlain by the Upper Triassic Mine Group. An analysis of the Tsunemori fauna shows an almost identical composition with that of the Akiyoshi Limestone Group. The ages of the limestone clasts of the Tsunemori Formation nearly completely coincide with those of the strata of the Akiyoshi Limestone Group. The Akiyoshi Limestone Group is subdivided into 28 foraminiferal zones, and faunal elements corresponding to 24 of these 28 zones are recognized in limestone blocks and fragments of the Tsunemori Formation. Species from the remaining four zones (late Visean Endothyra sp. Zone, the late Moscovian Fusulinella bocki Zone, early Asselian Sphaeroschwagerina fusiformis Zone, and Bolorian Misellina dyhrenfurthi Zone) in the Akiyoshi Limestone Group have not been found in the Tsunemori Formation, whose blocks and fragments are thought to have been all derived from the ancient Akiyoshi seamount. A limestone conglomerate previously assigned to the basal conglomerate of the Mine Group should be separated from the Mine Group and instead included in the Tsunemori Formation. Twelve species of foraminifers are systematically described.
Discovery of Gaudryceras tombetsenseMatsumoto, 1984 in the Futakawa Formation of the Sotoizumi Group in the Aridagawa area, Wakayama, southwestern Japan establishes that this formation includes sediments of early Late Maastrichtian age, which is the youngest record of the Sotoizumi Group distributed in Shikoku and the Kii Peninsula. The occurrence of the youngest fossils from the easternmost area of the Sotoizumi Group may support the suggestion that the depocenter of the Sotoizumi basin migrated eastward due to movement along the Kurosegawa Tectonic Zone (KTZ), which was still active during Campanian to Maastrichtian time.
Azooxanthellate coral species obtain nutrients by themselves, retaining their colonial growth forms independently of other species. This study examines the regularity of budding in the bushy, azooxanthellate scleractinian oculinid Cyathelia axillaris in order to identify the developmental constraints on colony formation and the ecological significance of colonial forms. The sympodial form of C. axillaris develops its bushy morphology by repeated dichotomous branching without clear axial corallites. The regularities in budding process are as follows: (1) in most cases, two buds originate simultaneously on opposite sides of medially constricted corallites near two parental second-order septa at individual distal ends; (2) the two directive septa of lateral corallites are oriented almost perpendicular to the directive septa of the immediate parental corallites; (3) the lateral corallites grow more or less diagonally upwards; and (4) these regularities remain valid from parental to derived lateral corallites throughout growth. Thus, apparently complex, threedimensional colonies with numerous offsets are formed according to certain rules, irrespective of the generation of individual corallites. The strict developmental constraints and the subtle modifications on asexual reproduction greatly affect the colonial growth that is unique to C. axillaris, for which the regularities in budding are effective and adaptive ways of utilizing limited resources (i.e., growth spaces and nutrients).
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