The Global Stratotype Section and Point (GSSP) for the base of the Katian Stage of the Upper Ordovician Series at Black Knob Ridge, Southeastern Oklahoma, USA

The International Subcomission on Ordovician Stratigraphy (ISOS) of the International Commission on Stratigraphy (ICS) recently defined the base of the global Upper Ordovician Series to be at the first appearance datum (FAD) of the graptolite species Nemagraptus gracilis in the Fågelsång GSSP in southern Sweden. This designation recognized the tremendous utility for global correlation of the first appearance of a cosmopolitan taxon that occurs within a consistent succession of other first appearance datums (e.g., Finney and Bergström, 1986; Bergström et al., 2000). Current efforts by the ISOS have focused on subdividing the Upper Ordovician into three stages and choosing appropriate levels and stratotypes for the bases of the middle and upper of these stages. The purpose of the present report is to describe the GSSP of the middle stage, for which the name Katian Stage was approved by the ISOS and ratified by the ICS in 2006 (Bergström et al., 2006). For a recent review of the long process of developing the new subdivisions of the Ordovician, see Finney (2005)

An Ordovician Global Reference Section Recently Selected in Oklahoma

Ordovician fossil faunas are characterized by a marked biogeographic differentiation that results in a minimal similarity between most North American faunas and those of major Ordovician areas elsewhere in the world. This provincial distribution of most fossils has led to establishment of different schemes of fossil-based regional stages in, for instance, North America, Baltoscandia, China, and the British Isles. Because these chrono-stratigraphic units have been largely based on shelly fossils with distributions restricted to a particular region, it has been impossible in most cases to establish a precise international correlation of these regional stages. Furthermore, some general terms, such as the Middle Ordovician;\u27 have a vastly different stratigraphic scope in different parts of the world causing confusion among stratigraphers and non-stratigraphers alike. Indeed, in view of the fact that many of today\u27s geology studies are of more than regional nature, there has been an urgent need for an international chronostratigraphic classification

Mind-reading ability: Beliefs and performance

Every adult possesses and uses to a various extent, a powerful tool, a theory of mind. The ability to recognize emotions, intentions, and thoughts of others is an important component of social competence. The use of personality questionnaires implies that people are aware of their personality traits, experienced emotions, values, and attitudes. Therefore, it is reasonable to expect that a normal adult is aware of his or her mind-reading abilities and can estimate, in relation to the others, how good he or she is at judging other person’s traits, states of mind, emotions, and intentions. In this study we have demonstrated that a person’s beliefs about their own mind-reading ability forms a single and unitary dimension. If a person believes that he or she is competent in forming judgments about another person’s personality traits then he or she has a relatively high opinion of their abilities to read another person’s thoughts and emotions. However, the results of our research show that the self-reported mind-reading ability was not correlated with actual performance. Those who believe that they are good at reading others’ minds are generally neither (1) significantly better than the others in recognition of emotions expressed in face or speech, nor (2) superior in their estimation of the personality traits of a stranger. The self-reported mind-reading ability was correlated with personality traits but not with psychometrically measured intelligence. On the contrary, the actual mind-reading performance was correlated with IQ scores. It is discussed why individuals are relatively accurate in estimation of their own personality but lack metaknowledge about their mind-reading abilities

Epipelagic chitinozoan biotopes map a steep latitudinal temperature gradient for earliest Late Ordovician seas: Implications for a cooling Late Ordovician climate

The Early–Mid Ordovician has long been considered a super-greenhouse world, based largely on high relative global sea levels and light stable oxygen isotope data from bulk carbonates. An alternative and largely untested hypothesis has suggested that, at least in equatorial palaeolatitudes, there was a steady cooling trend through the Early Ordovician reaching the range of modern equatorial sea surface temperatures by the Mid Ordovician. This hypothesis, though controversial, is supported by palaeobiogeographical studies of the early Late Ordovician (Sandbian) zooplankton (graptolite) biotopes. These are comparable to the modern planktonic foraminifera ‘provinces’ and suggest a latitudinal temperature gradient that is similar to the modern one.Chitinozoans are also an important group of Palaeozoic marine microfossils, but with a poorly known biological affinity. Here we present an analysis of chitinozoan species palaeobiogeography for the early Late Ordovician (Sandbian c. 460 Ma), which confirms that these microfossils, and likely their parent organisms, were epipelagic. Unlike the graptolites, chitinozoans had their highest diversity and abundance south of ~ 35°S during this time, which strongly suggests adaptation to temperate to cold waters. The distribution of chitinozoan biotopes during the gracilis time-slice allows us to identify the austral Subtropical, Subpolar and Polar belts; key oceanographic boundaries are identified as the Subtropical–Subpolar Transition at ~ 35°S and tentatively, the Polar Front at ~ 55°–70°S. Again, these are in a similar position to those in the modern Southern Ocean. Chitinozoan biotopes also map a steep latitudinal faunal gradient that is comparable to that of the graptolites and that of modern plankton. This likely indicates a steep latitudinal temperature gradient for early Late Ordovician seas and questions the notion that this interval of Earth history had a greenhouse climate

Polar front shift and atmospheric CO₂ during the glacial maximum of the Early Paleozoic Icehouse

Our new data address the paradox of Late Ordovician glaciation under supposedly high pCO2 (8 to 22× PAL: preindustrial atmospheric level). The paleobiogeographical distribution of chitinozoan (“mixed layer”) marine zooplankton biotopes for the Hirnantian glacial maximum (440 Ma) are reconstructed and compared to those from the Sandbian (460 Ma): They demonstrate a steeper latitudinal temperature gradient and an equatorwards shift of the Polar Front through time from 55°–70° S to ~40° S. These changes are comparable to those during Pleistocene interglacial-glacial cycles. In comparison with the Pleistocene, we hypothesize a significant decline in mean global temperature from the Sandbian to Hirnantian, proportional with a fall in pCO2 from a modeled Sandbian level of ~8× PAL to ~5× PAL during the Hirnantian. Our data suggest that a compression of midlatitudinal biotopes and ecospace in response to the developing glaciation was a likely cause of the end-Ordovician mass extinction

Polar front shift and atmospheric CO2 during the glacial maximum of the Early Paleozoic Icehouse

Our new data address the paradox of Late Ordovician glaciation under supposedly high pCO2 (8 to 22× PAL: preindustrial atmospheric level). The paleobiogeographical distribution of chitinozoan (“mixed layer”) marine zooplankton biotopes for the Hirnantian glacial maximum (440 Ma) are reconstructed and compared to those from the Sandbian (460 Ma): They demonstrate a steeper latitudinal temperature gradient and an equatorwards shift of the Polar Front through time from 55°–70° S to ∼40° S. These changes are comparable to those during Pleistocene interglacial-glacial cycles. In comparison with the Pleistocene, we hypothesize a significant decline in mean global temperature from the Sandbian to Hirnantian, proportional with a fall in pCO2 from a modeled Sandbian level of ∼8× PAL to ∼5× PAL during the Hirnantian. Our data suggest that a compression of midlatitudinal biotopes and ecospace in response to the developing glaciation was a likely cause of the end-Ordovician mass extinction