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Important artifacts have been found in situ (i.e., not redeposited) within lacustrine deposits in the Valsequillo region. These deposits contain many diatoms which indicate an age corresponding to the Sangamonian Interglacial sensu lato (80,000 to ca. 220,000yr BP). Two of the four samples in this study are associated with the Dorenberg skull or with stratigraphic units which contain bifacial tools. The remaining two samples are from diatomaceous deposits which are also Sangamonian and stratigraphically above the artifact units. These four diatomaceous samples yielded 30 extinct and 143 extant diatom taxa. The ages of the four samples correspond to other diatomaceous samples (some of which are associated with artifacts) from nearby Valsequillo localities. A post-Sangamonian age for these four diatom-bearing samples is discounted by the presence of Navicula bronislaae and N. dorenbergi, both of which have short stratigraphic ranges and are known only from the Sangamonian (or its equivalents), and by 13 diatoms which evidently have known long stratigraphic ranges and extinctions before the end of the Sangamonian. An age no older than Sangamonian for the artifacts and their enclosing diatomaceous deposits is indicated by the presence of two diatoms (Epithemia zebra var. undulata and Navicula creguti) known only from Sangamonian (or = age) or younger and by an extant diatom, Cymbella cistula var. gibbosa (C. gibbosa), which has its first occurrence in the Sangamonian.
Year-round changes in species composition and flux of calcareous dinoflagellates at station JT (34°09.8′N, 141°59.3′E; water depth, 8942m; trap depth, 916m) are reported. A time-series of thirteen sediment-trap samples of 29 days each, between March 5, 1991 and March 2, 1992, provided materials for this study. Vegetative cysts of a calcareous dinoflagellate, Thoracosphaera heimii, were found to be overwhelmingly dominant forming >95% of the calcareous dinoflagellate associations in all trap samples. Its' flux ranges from 910,000 shells·m−2·day−1 in May, 1991, to 76,000 shells·m−2·day−1 in September, 1991. Cysts of other calcareous dinoflagellates (Leonella granifera, Calciodinellum albatrosianum and Calciodinellum levantinum) were also found, with a maximum flux of 11,000 shells·m−2·day−1 for C. albatrosianum between December, 1991 and January, 1992. Based on physiological information, we suggest that species flux depends on water mass distribution linked to migration of the path of the subtropical Kuroshio Current. High to moderate flux of T. heimii occurred when the current took a meandering or a straight nearshore pathway. Waters southeast of the current prevailed over the trap station during this time. The most favorable environment, May, 1991, for T. heimii production seems to occur around a shallow thermocline formed above Subtropical Mode Water (STMW) in the waters southeast of the current. The species flux dropped when the current took an offshore pathway and flowed over the trap station. Surface and subsurface waters of the Kuroshio Current, especially during summer to autumn, is not productive of this species. The species flux also dropped while a “cold water mass” (i.e. lower salinity water cut off from the subarctic Oyashio Current) emerged over the trap station. Three cysts, L. granifera, C. albatrosianum and C. levantinum, show broadly similar abundance fluctuations to T. heimii. This close relationship between temporal changes in T. heimii productivity and path migrations of the Kuroshio Current, which is linked to the wind stress field over the North Pacific, should potentially provide information for paleoclimatic reconstructions.
Specimens of a new soritid foraminifer were collected from Bird Island, of the Lizard Island Group, Great Barrier Reef, Australia. Differences in aperture arrangement, shape, and number, and in internal test morphology are reported which distinguish the Bird Island specimens from previously described soritines. The analysis supports the establishment of a new species that we name Amphisorus sauronesensis. Molecular systematic comparison suggests that the new species is closest to Amphisorus hemprichii (Ehrenberg 1839) and supports the placement of the new species in the genus Amphisorus (Quoy and Gaimard 1830). Cytological investigations indicate the presence of symbiotic dinoflagellates throughout A. sauronesensis sp. nov., with the highest concentration of symbionts located in the intermediate chambers.
A new, very small to small (2.4 to 4.6µm) reticulofenestrid coccolith, Reticulofenestra calicis n. sp., is described by scanning electron and light microscopy from the Lower Pliocene (Zone CN11 of Okada and Bukry 1980) of the South Caribbean Sea. The coccolith shows typical reticulofenestrid distal and proximal shields but the distal shield is surmounted by a cup-shaped structure formed from extensions of the inner and outer tube elements. A new genus is not introduced, although this structure is peculiar for reticulofenestrids. We base generic attribution on the distal shield morphology. The species occasionally has few slits between the distal shield elements. Attribution to the genera Reticulofenestra instead of Pseudoemiliania is discussed in detail.
R. calicis n. sp. is structurally similar to the modern Emiliania huxleyi var. corona and to Reticulofenestra maceria.
R. calicis n. sp., readily recognized under the light microscope in side view, has a short stratigraphic range. If the species proves not to be under strong ecological control, it will constitute a new biostratigraphic marker for subdivision of the R. pseudoumbilicus Zone.
The genus Semicytherura develops a broad thin calcareous lamella inside the adult carapace, and this feature is one of the characters which define this taxon. However, neither anatomical nor histological studies have so far been done on this character. In earlier works, the lamella was regarded as an extension of the marginal infold, i.e. the “calcified inner lamella cuticle.”
In this study scanning and transmission electron microscope observations have clarified that the lamella is a different structure from the outer lamella cuticle, and that the epidermis does not exist inside the lamella. The lamella is called the “prismatic layer,” because of its calcareous crystal form. Development of this layer causes a restriction of the epidermis, which has a function in respiration and metabolism. Species of this taxon are thought to support their respiratory and metabolic systems by their small body size and low energy of locomotion, or through some specialized structures in the epidermal layers.
As a symptom of evolution, human beings are always trying to better understand current and past events so as to be able to foresee future situations. In order to do that the development of new tools and/or methods is a must. Currently, the Modern Analog Technique (MAT) is one of the most used techniques in paleoceanography and it is applied for the quantitative reconstruction of environmental conditions of the past. Here we propose a new tool, PaleoAnalogs, a method that combines the MAT technique with an interactive analysis to produce faster and more accurate down core reconstructions of (i.e.) sea surface temperature. The tool is tested here using planktonic foraminifers from Pleistocene sediments in the Mediterranean sea, where a well-build database is available. PaleoAnalogs is programmed with flexibility in order to enable the use of this technique for different micropaleontological groups and it is available for any operating system.
Lakadongia indica n. gen., n. sp. erected by Matsumaru and Jauhri (2003) is a junior synonym of Setia tibeticaFerràndez-Cañadell 2002. The genus Lakadongia is based on ambiguous characters and misinterpretation of oblique sections, and it is considered invalid. The postulated evolutionary relationship of these Paleocene orbitoidiform foraminifera with those of Cretaceous age is not justified by structural similarities and inconsistent with the stratigraphical record.