Sunday, 2 August 2015

Death toll thought to have exceeded 120 as Cyclone Komen makes landfall in Bangladesh.

Over 120 people are feared to have died after Cyclone Komen made landfall in Bangladesh on 1 August 2015. The storm brought widespread flooding to coastal areas of northern Myanmar, Bangladesh and West Bengal, Odisha and Manipur States in India. In Myanmar flooding has displaced around 150 000 people and destroyed over 17 000 homes, with at least 27 known to have died. In southern Bangladesh 23 people are known to have died and more than 130 300 to have been displaced, with over a meter of rain being recorded within 24 hours in parts of Chittagong. In India the state of Manipur has suffered the worst flooding in thirty years, with around 100 000 people having been displaced from their homes, with parts of the state cut off by flooding and 20 people reported to have died in a single landslide event; landslides are are a common problem after severe weather events, as excess pore water pressure can overcome cohesion in soil and sediments, allowing them to flow like liquids. Approximately 90% of all landslides are caused by heavy rainfall. In Odisha State at least 500 000 people have been forced to flee their homes due to flooding and at least three people have died. In West Bengal over 200 000 people have been displaced and 180 000 homes damaged or destroyed, with much of the city of Kolkata under water, after several hydro-electric dams were forced to release water to avoid catastrophic overload. At least 48 people have died in the West Bengal.

Damage to a bridge caused by high floodwaters in Chandel District, Manipur. NDTV.

Tropical storms are caused by solar energy heating the air above the oceans, which causes the air to rise leading to an inrush of air. If this happens over a large enough area the inrushing air will start to circulate, as the rotation of the Earth causes the winds closer to the equator to move eastwards compared to those further away (the Coriolis Effect). This leads to tropical storms rotating clockwise in the southern hemisphere and anticlockwise in the northern hemisphere.These storms tend to grow in strength as they move across the ocean and lose it as they pass over land (this is not completely true: many tropical storms peter out without reaching land due to wider atmospheric patterns), since the land tends to absorb solar energy while the sea reflects it.

Flooding on the streets of Kolkata on 2 August 2015. The Economic Times.

The low pressure above tropical storms causes water to rise there by ~1 cm for every millibar drop in pressure, leading to a storm surge that can overwhelm low-lying coastal areas, while at the same time the heat leads to high levels of evaporation from the sea - and subsequently high levels of rainfall. This can cause additional flooding on land, as well as landslides.

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Ten people are known to have died and several more are missing after Cyclone Helen made landfall in Andhra Pradesh State, India, at about 1.30 pm local time (8.00 am GMT) on Friday 22...

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Calcified Lizard eggs with preserved embryos from the Early Cretaceous of Thailand.

Among living Vertebrate groups, Lizards show the most diverse range of reproductive strategies, with species known that reproduce sexually and parthanogenically  (check spelling – a form of asexual reproduction in which the female fertilizes her own eggs, rather than producing clones as in some Insects and Plants), as well as egg laying and viviparous (live-birthing) Lizards being known. The majority of Lizards produce soft-shelled eggs, with casings with a leathery or parchment-like casing, similar to the eggs of Turtles and Crocodiles, however some members of one group, the Geckoes, produce calcified eggs, similar to those of Birds. Calcified Lizard eggs are known in the fossil record from the Early Cretaceous onwards, and have generally been referred to the Gekkota, however there is no strong basis for this assumption, as these eggs have not been found in close association with adult Lizards nor produced examinable embryos, so the possibility that members of other Lizard groups produced calcified eggs in the past cannot be ruled out.

In a paper published in the journal PLoS One on 15 July 2015, Vincent Fernandez of the European Synchrotron Radiation Facility and the Evolutionary Studies Institute at the University of the Witwatersrand, Eric Buffetaut of the Laboratoire de Géologie de l’Ecole Normale Supérieure at the Centre National de la Recherche Scientifique, Varavudh Suteethorn of the Palaeontological Research and Education Centre at Mahasarakham University, Jean-Claude Rage of the Sorbonne Universités and the Muséum national d’Histoire Naturelle, Paul Tafforeau, also of the European Synchrotron Radiation Facility, and Martin Kundrát of the Subdepartment of Development and Evolution at Uppsala University and the Institute of Physiology of the Academy of Sciences of the Czech Republic, describe a series of calcified Lizard eggs with preserved embryos from the Early Cretaceous Sao Khua Formation of Sakhon Nakhorn Province in northeast Thailand.

Material and geological settings. (A) Map of Thailand showing outcrops of the Sao Khua Formation (in green) and (B) close-up on north-eastern-Thailand with location of Phu Phok; (C) and photograph of 4 of the eggs from Phu Phok (SK1-1, SK1-2, SK1-3 and SK1-4). Scale bar is 1 cm. Fernandez et al. (2015).

The eggs were collected during official field campaigns of the Royal Thai Department of Mineral Resources and examined at the European Synchrotron Radiation Facility in Grenoble, and have subsequently been placed in the collection of the Sirindhorn Museum in Phu Kum Khao. When collected the eggs were thought to have been produced by a Theropod Dinosaur, but examination with phase contrast synchrotron microtomography (multiple X-rays used to build up a three dimensional computer model of the internal structure of an object) revealed the presence of  disarticulated embryonic Lizard skeletons in the eggs.

Three-dimensional rendering of two fossil eggs and their enclosed embryonic bones from Phu Phok. (A) SK1-2. (B) SK1-1. Colours: red, skull and mandible; yellow, vertebrae; grey, ribs; green, pectoral and pelvic girdle; blue, limbs. Scale bar is 5 mm. Fernandez et al. (2015).

The eggs were all crushed, but are interpreted to have been about 18 mm in height and 11 mm in maximum diameter, giving them a volume of about 1.15 cm3. The shells of the eggs appear to comprise a single layer of calcitic material overlaying an inner layer of fibrous material. The surface ornamentation of the eggs is nodular, with two distinct sizes of nodules, one tall and one smaller. Beneath these nodes are funnel-shaped canals, with their tips opening at the tips of the nodes and with wider depressions on the inner surface; these are interpreted as pore-canals (which would have allowed the living egg to breath and regulate moisture). The calcite layer is comprised of large crystals arranged in a columnar manner, arranged in a fan-shaped pattern around the pores/nodes.

Eggshell morphology and microstructure of the eggs from Phu Phok. (A) 3D rendering of a portion of the surface of the eggshell of SK1-2 showing the distribution of nodes. (B) Tomogram of SK1-1 showing two eggshell fragments that slid in the egg, outer surfaces oriented to the top of the figure. The inner half of both shell fragments is displayed in darker shades of grey indicating the shell is less dense than the whiter outer half. The funnel-shaped depression (d) do not seem to be obstructed. The pore canals (p) are highlighted by the edge interference resulting from the phase contrast effect (black and white fringes). (C-D) SEM photographs of an eggshell fragment showing the fan-shaped pattern of crystal at the level of a surface node (n). Note the fibrous layer (f) underlining the eggshell. (D) Close up from (C). Scale bars in (A, B) are 500 μm. Fernandez et al. (2015).

Computerised tomography enabled the reconstruction of two embryos of slightly different ages, both apparently the same species of long-snouted, large-braincased Lizard. A number of features of the skulls and teeth of these specimens suggest that they are members of the Platynota, the group of Anguimorph Lizards that includes the modern Monitor and Bearded Lizards as well as the extinct Mosasaurs, and definitely not to the Gekkota. This is the first time that a calcified egg has been shown to have been to have been produced by a non-Gekkotan Lizard.

Skull and mandible of the anguimorph embryos from Phu Phok. (A,B) skull, dorsal (A) and lateral (B) views. (C) left mandible, lateral view. Colours: yellow, SK1-1; green, SK1-2; red, absent or incomplete bone replaced by symmetrical reconstruction. Anatomical abbreviations: a, angular; ar, articular; c, coronoid; d, dentary; e, epipterygoid; ec, ectopterygoid; end, calcified endolymph; eo, exoccipital; f, frontal; j, jugal; m, maxilla; mf, mental foramen; op, opisthotic; p, parietal; pbs, parabasisphenoid; pf, postfrontal; pl, palatine; po, postorbital; pr, prootic; prf, prefrontal; pt, pterygoid; q, quadrate; s, stapes; sa, surangular; sm, septomaxilla; soc, supraoccipital; sq, squamosal; v, vomer. Scale bars are 1 mm. Fernandez et al. (2015).

See also…

Casquehead Lizards, Corytophanidae, are a group of Iguanid Lizards found from the tropical forests of southern Mexico, through Central America to the northwest of South America. They belong to a group of Iguanians, the Pleurodonta, found today...

In the 1980s a large collection of Avian eggs were uncovered at the campus of theNational University of Comahue at Neuquén City in Argentinean Patagonia. These ages were located on a single...

The Loma del Pterodaustro lake deposits of Central Argentina have produced large numbers of the Pterosaur Pterodaustro guinazui, which is interpreted...

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Saturday, 1 August 2015

Evidence of Cereal cultivation by the Sea of Galilee during the last Glacial Maximum, 23 000 years ago.

The domestication of agricultural plants is thought to have begun in the Middle East around the onset of the Holocene, about 11 700 years ago, with agriculture rapidly spreading across Europe, Asia and northern Africa as the practice was either adopted by hunter-gatherer communities or these communities were replaced by peoples who had adopted the new technology. Evidence for such agriculture comes not just from the presence of crops at archaeological sites, but also the presence of agricultural weeds, plants which have evolved to invade cultivated fields but which are not themselves cultivated. However caution needs to be used when relying on this form of evidence, as they are derived from wild plants specializing in the colonizing of disturbed ground, many of which have long histories of close associations with Humans, due to our habit of modifying environments by fire or other methods of clearing.

In a paper published in the journal PLoS One on 22 July 2015, Ainit Snir of the Martin (Szusz) Department of Land of Israel Studies and Archaeology at Bar Ilan University, Dani Nadel and Iris Groman-Yaroslavski of the Zinman Institute of Archaeology at Haifa University, Yoel Melamed of the Mina and Everard Goodman Faculty of Life Sciences at Bar-Ilan University, Marcelo Sternberg of the Department of Molecular Biology and Ecology of Plants at Tel Aviv University, Ofer Bar-Yosef of the Department of Anthropology at Harvard University and Ehud Weiss also of the Martin (Szusz) Department of Land of Israel Studies and Archaeology at Bar Ilan University discuss the presence of seeds from agricultural crops and weeds at the 23 000-year-old Ohalo II site on the southwest shore of the Sea of Galilee in southern Israel.

The Ohalo II site was occupied during the last Glacial Maximum by people interpreted as settled hunter-gatherers. The site comprises six brush huts, and several hearths (fire places) as well as a single grave, of an adult male. The site was inundated by rising waters on the Sea of Galilee shortly after it was abandoned, and remained covered by water until 1989, when it was exposed following several years of heavy water extraction from the lake. The site was excavated between 1989 and 1991 and again between 1998 and 2001.

Location map of Ohalo II and central area of excavation at the site. Snir et al. (2015).

Ohalo II has yielded a large number of seeds and fruits (about 150 000 specimens) suggesting the people enjoyed a diet including emmer wheat, barley, peas, lentils, almonds, figs, grapes and olives, similar to that of later agricultural peoples in the Middle East. The site is inferred to have been settled year-round from the presence of remains of migratory Birds which would have been present at different times of year and seeds and fruits from plants which would also have been produced at different times. As well as a wide range of artefacts and food remains, the site also shows evidence of invasion by pest species, including House Mice, Mus musculus, and Black Rats, Rattus rattus.

As well as a wide variety of food seeds, a large number of seeds from weed species were also recovered (15 726 identified specimens, about 10.5% of the total sample). These comprised thirteen different weed species, though the sample was dominated by Corn Cleavers, Galium tricornutum, with the presence of Darnel, Lolium temulentum, also considered to be important. These two plants are particularly significant as they are only known as agricultural weeds growing in cereal fields today, with their original habitat unknown. Four other species present, Chenopodium album, Malva parviflora, Notobasis syriaca and Silybum marianum, are also considered agricultural weeds today, though these species are also sometimes eaten, so caution needs to be used when implying their significance at archaeological sites.

When working with Holocene cereal samples archaeologists typically separate cultivated crops from wild plants by the disarticulation scars on their rachises (expand), with smooth scars being considered ‘wild-type’ and rough scars ‘domestic’; where more than 10% of the sample has domestic rough scars it is thought that the sample is likely to be of agricultural rather than wild origin. The Ohalo II samples of two cereals exceed this limit, with Wild Barley, Hordeum spontaneum, yielding 36% domestic-type scars and Wild Wheat, Triticum dicoccoides, yielding 25% domestic-type scars.

Wild-type (left) and domestic-type (right) scars in rachises of Wild Barley, Hordeum spontaneum, from Ohalo II. Snir et al. (2015).

Snir et al. are cautious in their interpretation of these results, noting that the ‘rough’ domestic scar is typically the result of harvesting dry, yellow seeds rather than green or yellow-green seeds, rather than any inherent difference in the plants. Domestic fields of cereals are planted at the same time and mature at the same time, leading to farmers being able to harvest more-or-less entirely yellow seeds. With wild-growing cereals plants at different stages of maturity tend to be present, leading to a mixture of yellow, yellow-green and green seeds being harvested, typically leading to a ‘wild-type’ sample, with a high proportion of smooth scars. However a number of experiments on Wild Barley harvesting at different sites in Israel have shown that a high level of smooth, domestic type, scars can be achieved if the plants are allowed to dry between harvesting and winnowing, suggesting that the Ohalo II sample could be a result of the practices used in food preparation rather than evidence of agriculture.

Wild Barley, Hordeum spontaneum. (A) Wild Barley field in Yakum Park (18 March 2013). It grows here with other species such as Galium aparine, Chrysanthemum coronarium, Notobasis syriaca, and Anthemis sp. (B) Same field, showing wild barley at three ripening stages – green, green-yellow and yellow. Snir et al. (2015).

The Ohalo II site has also produced a number of flint sickle-blades with a distinctive glossed surface pattern. This is considered typical of the Early Holocene Natufian culture, found in the Middle East roughly 10 000 years later than the Ohalo II site is thought to have been occupied. Experimental work on harvesting with flint tools has shown that such a smooth surface can be produced by cutting green and yellow-green cereal stems; this lends support to the idea that the Ohallo II inhabitants were harvesting green and yellow-green cereals then allowing them to dry before winnowing, and also suggests that the similarity between Ohalo II and Natufian tools is a product of similar practices rather cultural continuity.

Sickle blade from Ohalo II. (A) Macrograph of the sickle blade. (B) Micrograph showing the use-wear polish produced by cereal harvesting, observed along the sharp edge of the blade (original magnification ´ 200). (C) Micrograph showing hafting wear including streaks of polish associated with rounding observed along the opposite edge (original magnification ´ 100). Snir et al. (2015).

Snir et al. do not suggest that agriculture began at, or close to, Ohalo II 10 000 years earlier than previously realized and subsequently spread across the Middle East, but rather that some experimentation with plants that later became agricultural crops was occurring at this time. They note that this is common in palaeoarchaeological studies, with evidence suggesting that many technologies show a long period of experimentation before they are perfected and become widespread. There is no evidence to suggest that the practices present at Ohalo II led directly to later development of agriculture across the Middle East, but they do indicate that the population, reacted to similar environmental conditions as the later proto-agriculturalists in a similar way, by experimenting with the control and harvesting of cereal crops that became possible once the population was permanently settled in an area where these plants naturally occurred.

See also…

Early modern Humans expanded from Africa around the globe in the Late Pleistocene, from about 125 000 years ago onwards. In doing so they adapted to a wide variety of environments, though some habitats are thought...

Stone tools associated with the Acheulian technology first appeared around 1.75 million years ago and spread across much of Eurasia from about 900 000 years ago onwards. The technology is typified by tools in which pieces are chipped away from a central core to leave...

The Nefud Desert lies in the northwest of Saudi Arabia, and is thought to have been one of the key obstacles that early Humans, and other Hominids, had to pass as they expanded out of Africa into Southwest Asia...

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Catasetum telespirense: A new species of epiphytic Orchid from the southern Brazilian Amazon.

In 2011-2012 a series of series of rescue expeditions recovered and relocated around 105 000 epiphytic plants (plants which live on other plants, typically the branches of canopy trees) from the site of the planned Teles Pires Power Plant, which straddles the borders between Paranaíta County in Mato Grosso State and Jacareacanga County in Pará State on the banks of the River Teles Pires. This area is poorly explored by botanists, despite being an area high biodiversity, and many new species were discovered during this operation.

In a paper published in the journal Phytotaxa on 27 March 2015, Adarilda Petini-Benelli of the Instituto de Biociências at the Universidade Federal de Mato Grosso and Célia Regina Araújo Soares-Lopes of the Herbário da Amazônia Meridional at the Universidade do Estado de Mato Grosso describe a new species of epiphytic Orchid from the Teles Pires Power Plant site.

The new species is placed in the genus Catasetum, which currently contains at least 130 species of epiphytic Orchids with many undiscovered species thought likely to be present in unexplored areas of the Amazon, and given the specific name telespirense, in reference to the area where it was found. Catasetum telespirense is an epiphytic herb consisting of a 10-18 cm pseudobulb with 5-7 narrow leaves 20-45 cm in length growing from its base. These leaves are generally shed before the production of the inflorescence (flower-stem), also from the base of the plant. This is 20-45 cm in length and bears 2-10 fragrant yellow or yellow-green flowers 40-45 mm in width.

Male flowers from three specimens of the Catasetum telespirense showing different colours and lip forms. Adarilda Petini-Benelli in Petini-Benelli & Soares-Lopes (2015).

Catasetum telespirense was observed in the wild only at the Teles Pires Power Plant site, which is now lost to development. However discussions with Orchid collectors in Guarantã and Paranaíta Counties in Mato Grosso State and Jacareacanga  County in Pará State revealed that many had specimens of this plant, which most claimed had been collected from sites designated for development, in order to protect the plants, though one collector did admit collecting specimens from an unthreatened site. Clearly both urban development and unregulated collecting of the plants have implications for the conservation of Catasetum telespirense, and Petini-Benelli & Soares-Lopes suggest that the Orchid should be listed as Endangered under the terms of the International Union for the Conservation of Nature’s Red List of Threatened Species, due to the limited known range of the species, the low number of specimens recorded within this area, and the threats posed to the species by human activity.

Catasetum telespirense, general view of the plant flowering and without leaves, male flowers. Alexandre da Silva Medeiros in Petini-Benelli & Soares-Lopes (2015).

See also…

Orchids of the genus Liparis are found across tropical Asia, New Guinea, the islands of the southwest Pacific and tropical and subtropical regions of the Americas. There are currently sixty five species known to grow...

Orchids of the genus Gastrodia are found across temperate and tropical Asia, Oceania and Madagascar. They are mycoheterotrophs; parasitic plants which obtain nutrients and sugars from Mycorrhizal Fungi(Fungi which normally form symbiotic...

The International Union for the Conservation of Nature published its annual update of its Red List of Threatened Species on Thursday 12 June 2014, marking the 50th year of the list's existence, and revising the status of a number of Plant and Animal species from around the...

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Friday, 31 July 2015

Asteroid 2015 OQ21 passes the Earth.

Asteroid 2015 OQ21 passed by the Earth at a distance of 567 900 km (1.48 times the average distance between the Earth and the Moon, or 0.38% of the average distance between the Earth and the Sun), at about midnight GMT between Thursday 23 and Friday 24 July 2015. There was no danger of the asteroid hitting us, though had it done so it would have presented only a minor threat. 2015 OQ21 has an estimated equivalent diameter of 4-16 m (i.e. it is estimated that a spherical object with the same volume would be 4-16  m in diameter), and an object of this size would be expected to explode in an airburst (an explosion caused by superheating from friction with the Earth's atmosphere, which is greater than that caused by simply falling, due to the orbital momentum of the asteroid) in the atmosphere between 43 and 25 km above the ground, with only fragmentary material reaching the Earth's surface.

The calculated orbit of 2015 OQ21. JPL Small Body Database.

2015 OQ21 was discovered on 19 July 2015 (four days before its closest approach to the Earth) by the University of Hawaii's PANSTARRS telescope on Mount Haleakala on Maui. The designation 2015 OC21 implies that it was the 528th asteroid (asteroid C21) discovered in the second half of July  2015 (period 2015 O).

2015 OQ21 has a 254 day orbital period, with an elliptical orbit tilted at an angle of 1.33° to the plain of the Solar System which takes in to 0.50 AU from the Sun (50% of the distance at which the Earth orbits the Sun, considerably inside the orbit of Venus) and out to 1.07 AU (7% further away from the Sun than the Earth). This means that close encounters between the asteroid and Earth are fairly common, with the last thought to have happened in April this year and the next predicted in May 2017. Although it does cross the Earth's orbit and is briefly further from the Sun on each cycle, 2015 OQ21 spends most of its time closer to the Sun than we are, and is therefore classified as an Aten Group Asteroid. This also means that close encounters between 2015 OQ21 and Venus are quite common, with the last having occurred in February 2010 and the next predicted for August 2016.

See also...

Asteroid (242191) 2003 NZ6 passed by the Earth at a distance of 12 470 000 km (32.4 times the average distance between the Earth and the Moon, or 8.33% of the average distance between the Earth and the...

Asteroid (385186) 1994 AW1 passed by the Earth at a distance of 9 725 000 km (25.3 times the average distance between the Earth and the Moon, or 6.50% of the average distance between the Earth and the...

Asteroid 2011 YC29 passed by the Earth at a distance of 9 438 000 km (24.5 times the average distance between the Earth and the Moon, or 6.31% of the average distance between the Earth and the Sun), at about 10.10 am GMT on Wednesday 15 July...

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Magnitude 1.3 Earthquake near Glencoe, Scotland.

The British Geological Survey recorded a Magnitude 1.3 Earthquake at a depth of about 10 km about 5 km to the west of Glencoe in the district of Lochaber in Highland, Scotland, slightly after 9.25 pm British Summertime (slightly after 10.35 pm GMT) on Thursday 20 July 2015. This was not a major event, and presented no threat to human life or property, but was felt in the village of Ballachulish.

The approximate location of the 20 July 2015 Lochaber Earthquake. Google Maps.

Earthquakes become more common as you travel north and west in Great Britain, with the west coast of Scotland being the most quake-prone part of the island and the northwest of Wales being more prone  to quakes than the rest of Wales or most of England. 

The precise cause of Earthquakes in the UK can be hard to determine; the country is not close to any obvious single cause of such activity such as a plate margin, but is subject to tectonic pressures from several different sources, with most quakes probably being the result of the interplay between these forces.

Britain is being pushed to the east by the expansion of the Atlantic Ocean and to the north by the impact of Africa into Europe from the south. It is also affected by lesser areas of tectonic spreading beneath the North Sea, Rhine Valley and Bay of Biscay. Finally the country is subject to glacial rebound; until about 10 000 years ago much of the north of the country was covered by a thick layer of glacial ice (this is believed to have been thickest on the west coast of Scotland), pushing the rocks of the British lithosphere down into the underlying mantle. This ice is now gone, and the rocks are springing (slowly) back into their original position, causing the occasional Earthquake in the process. 

(Top) Simplified diagram showing principle of glacial rebound. Wikipedia. (Bottom) Map showing the rate of glacial rebound in various parts of the UK. Note that some parts of England and Wales show negative values, these areas are being pushed down slightly by uplift in Scotland, as the entire landmass is quite rigid and acts a bit like a see-saw. Climate North East.

Witness accounts of Earthquakes can help geologists to understand these events, and the structures that cause them. If you felt this quake, or were in the area but did not (which is also useful information) then you can report it to the British Geological Survey here.

See also...

The British Geological Survey recorded a Magnitude 1.4 Earthquake at a depth of about 2 km off the south coast of the Isle of Mull, in Argyll and Bute, Scotland...

The British Geological Survey recorded a Magnitude 1.3 Earthquake at a depth of about 3 kmto the west of Loch Rannoch in Perth and Kinross, Scotland, slightly...

The British Geological Survey recorded a Magnitude 2.2 Earthquake at a depth of about 11 km to the south of Loch Shiel in...

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