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Kent Brooks C.,Natural History Museum of Denmark
Geological Survey of Denmark and Greenland Bulletin | Year: 2011

The Palaeogene North Atlantic Igneous Province is among the largest igneous provinces in the world and this review of the East Greenland sector includes large amounts of information amassed since previous reviews around 1990. The main area of igneous rocks extends from Kangerlussuaq (c. 67°N) to Scoresby Sund (c. 70°N), where basalts extend over c. 65 000 km 2, with a second area from Hold with Hope (c. 73°N) to Shannon (c. 75°N). In addition, the Ocean Drilling Project penetrated basalt at five sites off South-East Greenland. Up to 7 km thickness of basaltic lavas have been stratigraphically and chemically described and their ages determined. A wide spectrum of intrusions are clustered around Kangerlussuaq, Kialeeq (c. 66°N) and Mesters Vig (c. 72°N). Layered gabbros are numerous (e.g. the Skaergaard and Kap Edvard Holm intrusions), as are under- and oversaturated syenites, besides small amounts of nephelinite-derived products, such as the Gardiner complex (c. 69°N) with carbonatites and silicate rocks rich in melilite, perovskite etc. Felsic extrusive rocks are sparse. A single, sanidine-bearing tuff found over an extensive area of the North Atlantic is thought to be sourced from the Gardiner complex. The province is famous for its coast-parallel dyke swarm, analogous to the sheeted dyke swarm of ophiolites, its associated coastal flexure, and many other dyke swarms, commonly related to central intrusive complexes as in Iceland. The dyke swarms provide time markers, tracers of magmatic evolution and evidence of extensional events. A set of dykes with harzburgite nodules gives unique insight into the Archaean subcontinental lithosphere. Radiometric dating indicates extrusion of huge volumes of basalt over a short time interval, but the overall life of the province was prolonged, beginning with basaltic magmas at c. 60 Ma and continuing to the quartz porphyry stock at Malmbjerg (c. 72°N) at c. 26 Ma. Indeed, activity was renewed in the Miocene with the emplacement of small volumes of basalts of the Vindtoppen Formation to the south of Scoresby Sund. Although the basalts were extruded close to sea level, this part of East Greenland is a plateau raised to c. 2 km, but the timing of uplift is controversial. Superimposed on the plateau is a major dome at Kangerlussuaq. East Greenland presents a rich interplay between magmatic and tectonic events reflecting the birth of the North Atlantic Ocean. It was active over a much longer period (36 Ma) than other parts of the province (5 Ma in the Hebrides, Northern Ireland and the Faroe Islands) and contains a wider range of products, including carbonatites, and felsic rocks tend to be granitic rather than syenitic. As expected, there are many similarities with Iceland, the present-day expression of activity in the province. Differences are readily explained by higher production rates and the thicker lithospheric lid during the early stages of development in East Greenland. The igneous and related activity clearly results from plate-tectonic factors, but the relationship is not understood in detail. In particular, the nature of the underlying mantle processes, primarily the presence or absence of a plume, is still not resolved. © De Nationale Geologiske Undersøgelser for Danmark og Grønland (GEUS), 2011. Source

Andreev P.S.,University of Birmingham | Cuny G.,Natural History Museum of Denmark
Journal of Vertebrate Paleontology | Year: 2012

This study identifies three new neoselachian tooth taxa from the Middle and Upper Triassic. On the basis of morphological and histological characters, Rhomaleodus budurovi, nov. gen. et sp. (Anisian of Bulgaria), is resolved as stem selachimorph, with an additional specimen from the same stratigraphic level assigned to Synechodus sp. Selachimorph grade of enameloid microstructural organization (crystalline bundles) was also identified during examination of the dental tissues of Polyacrodus holwellensis (Rhaetian of England), necessitating its transfer to the new genus Duffinselache. The present data reveal several levels of increasing architectural complexity in the arrangement of the enameloid crystalline bundles of stem selachimorphs, which are argued to convey a phylogenetic signal that can be used to establish relationships within the group. It is suggested that the evolution of the hypermineralized enameloid cover of neoselachian teeth progressed from a plesiomorphic single crystalline state, through amalgamation of individual crystals into loosely defined bundles (marking the appearance of Selachimorpha), and their subsequent differentiation into a highly ordered parallel bundles, followed by the development of an inner layer of haphazardly oriented bundles. The superficial shiny-layered enameloid of Neoselachii is interpreted as remnant of a much reduced single crystalline layer. © 2012 by the Society of Vertebrate Paleontology. Source

Djernaes M.,University of Alberta | Klass K.-D.,Senckenberg Naturhistorische Sammlungen Dresden | Picker M.D.,University of Cape Town | Damgaard J.,Natural History Museum of Denmark
Systematic Entomology | Year: 2012

We addressed the phylogeny of cockroaches using DNA sequence data from a broad taxon sample of Dictyoptera and other non-endopterygotan insect orders. We paid special attention to several taxa in which relationships are controversial, or where no molecular evidence has been used previously: Nocticolidae, a family of small, often cave-dwelling cockroaches, has been suggested to be the sister group of the predaceous Mantodea or of the cockroach family Polyphagidae; Lamproblatta, traditionally placed in Blattidae, has recently been given family status and placed as sister to Polyphagidae; and Saltoblattella montistabularis Bohn, Picker, Klass & Colville, a jumping cockroach, which has not yet been included in any phylogenetic studies. We used mitochondrial (COI + COII and 16S) and nuclear (18S and 28S) genes, and analysed the data using Bayesian inference (BI) and maximum likelihood (ML). Nocticolidae was recovered as sister to Polyphagidae. Lamproblatta was recovered as sister to Blattidae, consistent with the traditional placement (not based on phylogenetic analysis). However, because of the limited support for this relationship and conflict with earlier morphology-based phylogenetic hypotheses, we retain Lamproblattidae. S. montistabularis was consistently placed as sister to Ectobius sylvestris Poda (Blaberoidea: Ectobinae), indicating that the saltatorial hindlegs of this genus are a relatively recent adaptation. Isoptera was placed within Blattodea as sister to Cryptocercidae. Nocticolidae + Polyphagidae was sister to Isoptera + Cryptocercidae, and Blaberoidea was sister to the remaining Blattodea. © 2011 The Authors. Systematic Entomology © 2011 The Royal Entomological Society. Source

News Article
Site: http://www.nature.com/nature/current_issue/

Plague was plaguing humanity thousands of years earlier than previously thought, but in a less transmissible form. Yersinia pestis bacteria, which are thought to have been behind the Black Death that killed millions in the fourteenth century, have previously been found in burial sites dating back 1,500 years. But Eske Willerslev at the Natural History Museum of Denmark in Copenhagen and his colleagues looked even further back. They analysed DNA obtained from the teeth of 101 humans (pictured) who died in Europe and Asia between 2,800 and 5,000 years ago and found Y. pestis DNA in seven individuals. Analysis of the DNA showed that a strain similar to the Black Death strains was widespread in the Bronze Age, but only the more recent strains had a gene called ymt, which helps Y. pestis to colonize the guts of fleas. Without fleas to aid transmission, plague spreads less efficiently.

News Article
Site: http://www.washingtonpost.com/news/energy-environment

In a new feat of high-powered genetic research, a group of scientists has found that the early human population of Europe went through dramatic changes over 10,000 years ago, as a result of sharp swings of the Earth’s climate that went from a major glacial period to a warm period, then snapped back to a freeze again over the course of millennia. As these events occurred, humans in Europe first experienced a “bottleneck” when their numbers decreased during the last Glacial Maximum roughly 25,000 to 19,500 years ago, says the new research, published Thursday in Current Biology. But later, as a warm period kicked in around 14,500 years ago, it looks like this population was replaced or overwhelmed by a genetically somewhat different one, which may have been able to migrate into the area, thanks to retreating ice. The paper calls this “surprising evidence of a major population turnover in Europe around 14,500 years ago,” at the same time when there was also “a period of climatic instability.” “I think it’s a very interesting correlation, and I don’t think this correlation is just by chance, especially for those hunter-gatherer cultures who are largely dependent on the environment,” said Johannes Krause, one of the study authors and a researcher at the Institute for Archaeological Sciences at the University of Tübingen in Germany. The research was conducted by Krause and no less than 34 other authors. The study, based on 55 early modern human genomes from the period between 35,000 and 7,000 years ago, examined mitochondrial DNA — DNA that is contained within cellular structures called mitochondria rather than in the nucleus where most of our genetic material is located, and is passed down from mothers to their offspring. Examining this DNA, scientists have found slight mitochondrial differences between Asians, Australians and Native Americans on the one hand, and Europeans on the other. European mitochondrial DNA today shows what is called the “N” lineage, or “haplogroup,” but not what is called an “M” lineage. By contrast, Asian, Australasian and Native Americans show both. The M lineage, the research explains, is “today found predominantly in Asia, Australasia, and the Americas, although it is almost absent in extant populations with European ancestry.” Because of this difference, it has been argued in the past that humans did not all leave Africa at the same time some 50,000 years ago — rather, they left in waves that were, genetically, somewhat different. But the new research suggests that genetic information characteristic of the M lineage was “unexpectedly” present in Europe — present-day France and Belgium — 35,000 and 28,000 years ago, although it is not today. That not only suggests a single human migration out of Africa; it also raises the question — what happened to these people who were once in Europe but did not persist there? The study suggests that as the Last Glacial Maximum set in between 25,000 and 19,500 years ago, ice sheets grew to a vast extent and covered much of the continent, as well as much of present-day North America. Populations of humans in Europe in this time were not only driven southward by the ice sheets but may also have been separated into isolated areas by them, what the researchers call “refugia.” “We had a large glacier coming down from Scandinavia that pushed out people from central Europe,” Krause said. At the same time, the populations decreased in size — what the researchers call a “genetic bottleneck that may have been influenced by climatic events” — and may have lost some of their genetic diversity, including the mitochondrial DNA characteristic of the M lineage. “What we found was that there was more genetic diversity before the Last Glacial Maximum,” Krause said. “During the Glacial Maximum, diversity got lost.” But then came a period called the Bølling-Allerod “interstadial” (interstadials are relatively warmer periods during ice ages), beginning about 14,500 years ago. Ice sheets retreated, and indeed, this is when humans crossed the land bridge from Asia to North America. Something similarly dramatic happened in Europe, the new research suggests. A new flux of humans, perhaps able to move to new territory as ice sheets retreated, appears to have come into Europe and effected a “replacement” of the older one. These people did show the “N” lineage characteristic of Europeans today. “The people who survive the ice age, they change again,” Krause said. “There is a turnover.” It isn’t known, Krause said, where this mysterious new group came from. Nor is it known whether this means the two groups fought, interbred, or simply that the incoming group was much larger and, in effect, subsumed the smaller one. “We do not know what happened about 14.5 thousand years ago. That is just too little data that we had,” he said. “Whether it was a traumatic event that caused those new people coming in, like a pandemic or sudden climatic change, or was the population just bigger, and they absorbed the smaller population.” But it seems likely that warmer conditions helped the event happen. At the same time, Krause noted, forests were regrowing across Europe around the same time, and there were extinctions of major land mammals (or megafauna), probably due in part to their hunting by humans. Later on came another cold snap — the Younger Dryas, beginning around 12,900 years ago and lasting another millennium. Then, finally, starting around 11,700 years ago, we moved into the current Holocene period, a warmer period of relative climatic stability that has fostered the growth of civilization. These climate snaps — warm, then cold again — are said by many scientists to involve shifts in the circulation of the Atlantic Ocean, whose “overturning” circulation is said to have started and stopped many times in Earth’s past. When it stops, less warm water is carried northward in the Northern Hemisphere, which triggers cooling in Europe and, some research suggests, potentially across the globe. [Why the Earth’s past has scientists so worried about the Atlantic Ocean’s circulation] It is important to note that while the new research does suggest significant mitochondrial DNA changes in human populations during these climate swings over 10,000 years ago, that does not mean that the world’s humans became substantially different from one another genetically. We’re all still the same species. “We’re focusing on minute differences in maternal ancestry here, definitely not huge differences,” said Jennifer Raff, a professor of anthropology at the University of Kansas who was not involved in the research, by email. However, these slight differences are permitting increasingly powerful studies of the history of human populations. The new research only used mitochondrial DNA — and on this basis, it will be “interesting to see what the nuclear genome shows,” said Eske Willerslev, a professor at the Centre for GeoGenetics at the Natural History Museum of Denmark, who was not involved in the study. Studies of this broader body of genetic material “has the potential power to reveal complex population histories,” Willerslev said by email. “This finding highlights how ancient DNA research is transforming our understanding of human history and evolution,” added the University of Kansas’s Raff by email. She continued:

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