The basic structural building block of the biomarkers is the isoprene unit (Figure 1A). The end closer to the methyl branch is called the "head/' and the other end is the "tail." Compounds formed biosynthetically from isoprene units are called "isoprenoids." Two isoprene units joined head-to-tail (with minor modifications, such as hydrogenation of double bonds) form a monoterpane (Figure IB). Two monoterpanes (four isoprene units) linked together form a diterpane, whereas six isoprene units can be joined either to form a sterane or a triterpane, depending upon how the linking is accomplished.

Pollen, diatom and foraminiferal analyses of a nearly complete Mikulino/ Eemian interglacial marine sequence in Petrozavodsk, Russian Karelia, is presented together with a comprehensive literature review of Mikulino biostratigraphical data in NW Russia earlier published mostly in Russian. Mikulino interglacial deposits have been investigated in numerous sites, and, similarly, palaeohydrology and duration and correlation of different phases of the Mikulino marine submergence in this region have also been under discussion in several papers.

Various palaeoecological trends have been identified in the Phanerozoic, each focusing on different aspects of the fossil record. Patterns that have been described include histories of tiering, palaeocommunity species richness, and guild occupation in evolutionary faunas, as well as onshore-offshore trends in origination, expansion and retreat. Patterns of change through time have also been documented from biosedimentological features (ichnofabrics, microbial structures, shell beds). Such trends can be compared and contrasted to yield unique insights into understanding the changing ecology of the past, and in particular may be helpful in evaluating the relative degree of ecological degradation caused by a mass extinction. This comparative approach can also shed light on a variety of fundamental palaeobiological problems, for example, why no new body plans (phyla) have evolved since the early Phanerozoic. Causes of this phenomenon are thought to be either: (1) ecospace was not sufficiently open after the early Phanerozoic for survival of new body plans; or (2) accumulating developmental constraints after the early Phanerozoic have prevented the evolution of new body plans. Because the Permian-Triassic mass extinction was the most devastating biotic crisis of the Phanerozoic, one might expect new body plans to appear if ecospace were the primary limiting factor and opened sufficiently by this mass extinction. Although previous studies have shown that ecospace availability in the Cambrian and Early Triassic was indeed different, this comparative approach indicates that ecological conditions in the Early Triassic were most like those of the Late Cambrian/Early Ordovician. Thus, if ecospace availability has constrained the survival of new body plans, then ecospace has always been sufficiently filled after the Cambrian explosion to inhibit their evolution.

Mud resistivity can be verified using the BKZ curve using the non –permeable interval with interval thickness / Bit Size > 16 and RT considerably higher than Mud resistivity.
BKZ departure curve is plotted on logarithmic transparency together with Bit Size constant vertical line (X axis AO/BS, Y axis Rapp/Rm). Bit size constant is overlaid with BS line on No-Invasion chart for appropriate device type (lateral or normal) The transparency is moved vertically along the BS line on the chart until the BKZ curve is matched with the chart (specifically the left part of the curve )  Verified RM  is defined as the Y value of the transparency grid crossed by Rapp / Rmud = 1 line (chart cross). Mud resistivity value is read from the transparency grid, RT defined as Y value on the chart grid where the BKZ measurement curve crosses the A line on the chart