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Principal component analysis (a) and cluster analysis (b) of Ordovician brachiopods of South China using time intervals as cases (based on graptolitic biozones) and brachiopod genera in each interval as variables. Six brachiopod faunas are recognized in the Ordovician: the Tritoechia Fauna, the Sinorthis Fauna, the Saucrorthis Fauna, the Foliomena Fauna, the Altaethyrella Fauna, and the Hirnantia Fauna. The Sinorthis Fauna could also be further differentiated into the Sinorthis Subfauna (a-2) and the Euorthisina Subfauna (a-1). The major faunal turnovers were represented by the appearance and disappearance of the Sinorthis Fauna. See Appendix A for details of faunal composition and the number code of brachiopod genera.
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The Ordovician radiation is the earliest and most important biodiversification event in the evolution of the Paleozoic Evolutionary Fauna (PEF), when the basic framework of PEF was established. The radiation underwent a gradual, protracted process spanning more than 40 million years and was marked by several diversity maxima of the PEF. Case studie...
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... of graptolitic biozones. In our study, a binary dataset, using graptolite biozones as cases and brachiopod genera as variables, was subjected to a multivariate analyses (principal component and cluster analyses) to detect major faunal dissimilarities between stratigraphically adjacent faunas (faunal turnovers) in the Ordovician of South China (Fig. 3). The cluster analysis indicated that the Sinorthis Fauna is the most distinct bra- chiopod fauna, showing a maximum difference in its gen- eric composition from any other Ordovician brachiopod faunas in South China. This implies two major brachiopod faunal turnover events, one being the transition from the Tremadocian Tritoechia Fauna ...Similar publications
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Over one hundred years of palaeontological research in northwestern Argentina has provided extensive knowledge of Andean lower Palaeozoic fossil assemblages, with trilobites, graptolites, brachiopods and echinoderms being among the most prominent groups. This record is enriched by the recent discovery of soft-bodied worms in Cambrian outcrops of no...
Early Silurian trilobites and graptolites from the Vargas Peña Formation of the western Paraná Basin are described. The studied material comes from two successions (San Fernando and Galeano quarries) on the southwestern flank of the Ypacaraí graben, about 30 km southeast of Asunción city, eastern Paraguay. The faunas include Calymene boettneri Harr...
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Citations
... The multivariate technique of cluster analysis (Hammer & Harper 2006) is widely used in palaeobiogeography for the identification of faunal differences between palaeocontinents, regions and faunas of various ages (Tychsen & Harper 2004;Harper et al. 2013), more specifically, in studies of the Ordovician biodiversification (Harper 2006) and faunal turnovers (Zhan et al. 2008). The present use of cluster analysis is somewhat unconventional and differs from those applications, because of its stratigraphically-oriented goals. ...
... Such conditions may also have occurred on the Jiangnan Slope adjacent to the Yangtze Platform, leading to differences among coral populations in the JCYT. A high degree of differentiation and endemism has been noted in Ordovician brachiopod faunas of South China (Zhan et al., 2008). ...
Catenipora is one of the most common tabulate coral genera occurring in various lithofacies in the Upper Ordovician Xiazhen Formation at Zhuzhai in South China. A combination of traditional multivariate analysis and geometric morphometrics is applied to a large number of specimens to distinguish and identify species. Based on three major principal components extracted from 11 morphological characters, three major groups as determined by the cluster-analysis dendrogram are considered to be morphospecies. Their validity and distinctiveness are confirmed by discriminant analysis, descriptive statistics, and bivariate plots. Tabularium area and common wall thickness are the most meaningful characters to distinguish the three morphospecies. Geometric morphometrics is adopted to compare the morphospecies with types and/or figured specimens of species previously reported from the vicinity of Zhuzhai. Despite discrepancies in corallite size, principal component analysis and discriminant analysis, as well as consideration of overall morphological characteristics, indicate that the morphospecies represent C. zhejiangensis Yu in Yu et al., 1963, C. shiyangensis Lin and Chow, 1977, and C. dianbiancunensis Lin and Chow, 1977.
Catenipora occurs in seven stratigraphic intervals in the Xiazhen Formation at Zhuzhai, representing a variety of heterogeneous environments. The coralla preservation is variable due to differential compaction; coralla preserved in limestones are commonly intact and in growth position, whereas those in shales are mostly crushed or fragmentary. The size and shape of corallites are considered primarily to be species-specific characters, but are also related to the depositional environments. In all species, morphological characters, including corallite size, septal development, and shape and size of lacunae, show high variability in accordance with lithofacies and stratigraphic position. The intraspecific differences in corallite size at various localities in the Zhuzhai area may indicate responses to local environmental factors, but may also reflect genetic differences if there was limited connection among populations.
... It has been suggested that, during the Great Ordovician Biodiversification Event (GOBE, also known as the Ordovician Radiation), the Paleozoic Fauna came to dominate in shallower waters and the Cambrian Fauna retreated offshore (Sepkoski and Sheehan, 1983;Sepkoski, 1991). This has been shown to be true in some cases, for example brachiopods (e.g., Patzkowsky, 1995;Harper, 2006), although it does not apply in all geographic areas (Zhan et al., 2008), nor does it apply to all other groups, such as trilobites (e.g., Westrop et al., 1995). Thus far, despite description of numerous Ordovician echinoderm faunas from individual deposits, data to test this idea directly for echinoderms in one localized region have not been available. ...
The Builth Inlier of central Wales exposes a highly fossiliferous Middle to Late Ordovician (Darriwilian to basal Sandbian) siliciclastic succession in a volcanic, back-arc basin setting. Articulated echinoderm faunas are preserved in a range of paleoenvironments, together with widespread, dissociated ossicles. These have enabled a reconstruction of the distributions of echinoderm groups across a range of noncarbonate facies. The oldest echinoderm assemblages are from sandstone and siltstone deposits, and have yielded only the crinoid Iocrinus pauli and rare asteroids. The most diverse echinoderm assemblages are from a nearshore siliciclastic facies at Llandegley Rocks and equivalent sites. These are dominated by crinoids, together with rare asteroids, caryocystitid rhombiferans, echinozoans, and possible mitrate stylophorans. Deeper-water environments were dominated by the mitrate stylophoran Anatifopsis, associated with variable numbers of holothurians, cornutes, solutans, and rare cystoids (rhombiferans and undetermined blastozoans). The ecological distribution of echinoderms in the area can be summarized as follows: (1) high-diversity faunas in the shallowest environments, composed primarily of large crinoids, with asterozoans and other groups; (2) low-diversity faunas in intermediate water depths, with crinoids (one species) and asterozoans; (3) moderately diverse faunas in deep-water communities with generally small taxa, dominated by stylophorans. These results agree with previous interpretations of environmental preferences among the different groups of echinoderms, but also indicate a separation of dominantly Cambrian-type classes in offshore sediments and Ordovician-type taxa in shallow water. Based on assessments of functional morphology and previously published data, the environmental distributions of these taxa are likely to have been controlled by a complex of factors including sediment type, flow regime, nutrient availability, and temperature. Shallow-water siliciclastic settings may have been crucial environments for echinoderm diversification during the Great Ordovician Biodiversification Event.
In this paper, we reported our experimental observations of the special scattered light inLiNbO3: Fe crystal. We studied the far-field scattering light of five kinds of configurations, respectively, when the angle between the direction of the c axis of the crystal and the direction of the incident long linear beam is 0°, 30°, 45°, 60°, 90°. We observed an interesting phenomenon firstly that strong light scattering appeared along the direction of the incident long linear beam on the crystal, and the scattering light is constituted of the filaments that perpendicular to the direction of the incident beam on the crystal in each situation. We also observed a new phenomenon that the scattering light appear perpendicular to the direction of the incident beam when the angle is 90°.
Extensive use of synthetic pyrethroids has resulted in concerns regarding their potential effects on human health and ecosystems.
In the present study, we evaluated the influence of coexisting Cu2+, Zn2+, soil water contents (15%, 25%, 40% by weight and waterlogged) and temperature levels (15°C, 25°C, 35°C, and 45°C) on the
dissipation of cypermethrin, fenvalerate and deltamethrin in red soil. To further clarify the influence of Cu2+ and Zn2+ on biological and chemical dissipation processes, serial concentrations of the synthetic pyrethroids containing Cu2+ (21.3, 50, 100, and 400mgkg−1) and Zn2+ (35.8, 100, 250, and 500mgkg−1) were used to spike the soil and then incubated at 25°C in the dark at 25% moisture. The results revealed a very severe inhibitory
effect on the dissipation rates with increasing Cu2+ and Zn2+ levels. Conversely, there were no significant decreases in dissipation rates in response to exposure to 50mgkg−1 Cu2+ or 100mgkg−1 Zn2+, and the dissipation rates decreased significantly (p < 0.05) when the Cu2+ and Zn2+ concentration increased to 100 and 250mgkg−1, respectively, which were the respective maximum field recommended rates. When compared with unsterilized batch treatments,
the t
1/2 in sterilized (chemical dissipation) batch treatments increased by 1.0–4.8-fold. Additionally, there was a highly significant
difference in the dissipation of pyrethroids in the 15% water content treatments and waterlogged treatments (p < 0.05). Finally, the difference in the dissipation rates at 15°C and 25°C was significant (p < 0.05).
KeywordsCypermethrin-Fenvalerate-Deltamethrin-Temperature-Water content
