Paleochorological studies of Selaginella selaginoides (L.) P. Beauv. ex Mart. et Schrank and Diphasiastrum alpinum (L.) Holub in the younger dryas within plain part of Ukraine

The data on the presence of spores of Selaginella selaginoides and Diphasiastrum аlpinum in the spore-pollen spectra of Younger Dryas sediment within plains part of Ukraine are presented. Currently, these two species are listed in the third edition of the Red Data Book of Ukraine (2009) and are involved in the formation of highlands vegetation of the Ukrainian Carpathians. We found that Selaginella selaginoides and Diphasiastrum аlpinum were part of the periglacial community of the forest, forest-steppe and steppe zones during the Younger Dryas in Ukraine. Paleopalynological materials are shown that Selaginella selaginoides was distributed both on the right bank and left-bank parts of these zones. The occurrence of Diphasiastrum аlpinum was limited to the right-bank part of the forest and steppe zones of Ukraine. As a result of our investigation, the sketch maps of distribution of Selaginella selaginoides and Diphasiastrum аlpinum within the plain part of Ukraine were developed

Palynomorphological features of Suaeda acuminata (C.A. Mey.) Moq., Suaeda prostrata Pall. and Tamarix ramosissima Ledeb.

The pollen morphology of Suaeda acuminata , S. prostratа and Tamarix ramosissima from Ukrainian flora has been studied with light and scanning electron microscopy. The main morphological features of pollen grains of three taxa, which spread within halophytes vegetation, are determined. The results has considered as potential useful for identification of the fossil pollen under paleopalynological or paleoecological study

Effects of sampling standardization on estimates of Phanerozoic marine diversification

Global diversity curves reflect more than just the number of taxa that have existed through time: they also mirror variation in the nature of the fossil record and the way the record is reported. These sampling effects are best quantified by assembling and analyzing large numbers of locality-specific biotic inventories. Here, we introduce a new database of this kind for the Phanerozoic fossil record of marine invertebrates. We apply four substantially distinct analytical methods that estimate taxonomic diversity by quantifying and correcting for variation through time in the number and nature of inventories. Variation introduced by the use of two dramatically different counting protocols also is explored. We present sampling-standardized diversity estimates for two long intervals that sum to 300 Myr (Middle Ordovician-Carboniferous; Late Jurassic-Paleogene). Our new curves differ considerably from traditional, synoptic curves. For example, some of them imply unexpectedly low late Cretaceous and early Tertiary diversity levels. However, such factors as the current emphasis in the database on North America and Europe still obscure our view of the global history of marine biodiversity. These limitations will be addressed as the database and methods are refined

Pollen-based biomes for Beringia 18,000, 6,000 and 0 14C yr B.P.

A biomization method, which objectively assigns individual pollen assemblages to biomes ( Prentice et al., 1996 ), was tested using modern pollen data from Japan and applied to fossil pollen data to reconstruct palaeovegetation patterns 6000 and 18,000 14C yr bp Biomization started with the assignment of 135 pollen taxa to plant functional types (PFTs), and nine possible biomes were defined by specific combinations of PFTs. Biomes were correctly assigned to 54% of the 94 modern sites. Incorrect assignments occur near the altitudinal limits of individual biomes, where pollen transport from lower altitudes blurs the local pollen signals or continuous changes in species composition characterizes the range limits of biomes. As a result, the reconstructed changes in the altitudinal limits of biomes at 6000 and 18,000 14C yr bp are likely to be conservative estimates of the actual changes. The biome distribution at 6000 14C yr bp was rather similar to today, suggesting that changes in the bioclimate of Japan have been small since the mid-Holocene. At 18,000 14C yr bp the Japanese lowlands were covered by taiga and cool mixed forests. The southward expansion of these forests and the absence of broadleaved evergreen/warm mixed forests reflect a pronounced year-round cooling