Wednesday, 22 October 2014

The role of aquatic polymers in transmitting disease in coastal ecosystems.

Toxoplasma gondii is a protozoan parasite that affects humans, and many other animals, across the globe. While it causes disease in many organisms, it reproduces only in Felids, particularly in Domestic Cats, with oocysts (egg-like cysts) being shed in Cat faeces spreading the disease to many other organisms (some of which are subsequently eaten by Cats). The response to infection is variable; in humans it can cause illness and even death, but many people appear to become infected without ever suffering symptoms.

The disease has been recorded in a variety of Marine Mammals off the coast of California, including Sea Otters, which appear to be particularly vulnerable, and there have been a number of cases of Humans becoming infected after consuming seafood or simply coming into contact with seawater in California. While it is possible for Toxoplasma gondii oocysts to reach the sea in runoff from land, the rate of infection seen in Californian Marine Mammals is hard to explain; oocysts can persist in the environment for years, but should still be at a far lower concentration in the sea than can explain the infection rates seen.

In a paper published in the Proceedings of the Royal Society SeriesB: Biological Sciences on 8 October 2014, a team of oceanographers, ecologists and epidemiologists from the University of California, Davis and University ofCalifornia, Santa Cruz, led by Karen Shapiro of the One Health Institute and Department of Pathology, Microbiology and Immunology at the School ofVeterinary Medicine at the University of California, Davis, describe the results of a series of investigations into the role of marine polymers in the transmission of Toxoplasma gondii in Californian coastal ecosystems.

Marine polymers are a diverse group of sticky organic chemicals produced by organisms for a variety of reasons, including defence (many organisms have a protective mucous coating), feeding (filter feeding and detritus consuming organisms often use mucus to aggregate small food particles into manageable clumps) and movement (such as the mucus trails left by Snails). They form drifting marine aggregates (marine snow), which tend to sweep up small particles in the water, aiding the settling of such particles onto the seafloor or other surfaces.

Firstly Shapiro et al. tested to concentration of Toxoplasma gondii oocysts in seawater with varying concentrations ofmarine polymers, finding that high concentrations of such polymers could raise the concentration of oocysts by up to 80%. This indicates that oocysts entering the marine ecosystem are highly likely to become associated with marine polymer aggregations, concentrating the infective particles, if causing them to settle out more rapidly (which is not a bad thing for the oocyst, settling close to shore where it may be consumed by a potential host is better than drifting into the open ocean where it will eventually die).

Toxoplasma gondii oocyst (arrow) associated with a TEP-embedded aggregate under DAPI epifluorescence. Shapiro et al. (2014).

Next Shapiro et al. looked at the ability of the Turban Snails Chlorostoma brunnea, Chlorostoma montereyi and Promartynia pulligo to absorb and transmit Toxoplasma gondii oocysts; it has previously been observed that Sea Otters that favour Turban Snails are more at risk of Toxoplasma gondii infection than those living in the same areas that favour other prey. The Turban Snails live on Kelp plants, where they consume mucus from the surface of the Kelp; the mucus is excreted by the Kelp as a defence, allowing the transmission of dissolved marine nutrients but excluding potentially harmful microorganisms. Shapiro et al. found that Turban Snails start to excrete Toxoplasma gondii oocysts in their faeces about 10 days after being exposed to a source of food contaminated with the oocysts, and that these oocysts are significantly concentrated in the faeces relative to the food.

Ventral surface of Turban Snail with enlargement of scraping radula. Shapiro et al. (2014).

Based upon these experiments Shapiro et al. propose the following mechanism for the transmission of Toxoplasma gondii in Californian coastal waters: The oocysts of the organism enter the water through runoff from the land at low concentrations, but are concentrated in floating aggregations of marine polymers. These aggregations may be consumed in the water column by filter feeding Fish such as Sardines, or settle out of the water column and be consumed by filter feeding shellfish such as Clams, both of which facilitate transmission to Humans via seafood.

In the specific case of Otters the chance of infection is significantly raised by the consumption of Turban Snails, which feed upon mucus on the surface of Kelp Plants (where the oocysts are likely to have become concentrated) and further concentrate the oocysts within their bodies.

Two mechanisms are proposed whereby polymers can mediate transmission of terrestrial pathogens in coastal ecosystems (depicted here for a modelzoonotic protozoan parasite, Toxoplasma gondii). Pelagic polymers such as TEPs may enhance the association of pathogens with sinking macroaggregates, while benthic exopolymer substances (EPS) can trap pathogens within sticky biofilms. Both mechanisms are likely to increase the probability ofpathogen entry into the marine food web through aggregate-consuming invertebrates such as Bivalves or surface scraping Molluscs such as Snails. Ingestion ofcontaminated prey items can then lead to pathogen exposure in susceptible hosts, including threatened California Sea Otters and Humans. Shapiro et al. (2014).

See also…

At least 467 people have died in an outbreak of  Ebola Hemorrhagic Fever in West Africa that began in February this year. The disease initially appeared in the remote border area between Guinea, Sierra Leone and...

Bull Kelp, Durvillaea antarctica, is a large Brown Algae forming dense colonies of fronds up to 8 m long on otherwise exposed rocky shores on the coasts of South America, New Zealand and the islands of the...

John Snow was a nineteenth century London doctor, who is widely credited with the discovery of the transmission mechanism of Cholera, a severe and often fatal infection of the small intestine caused by the bacterium Vibrio cholerae. In Snow's time our understanding of microbiology was in its infancy...

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The discovery of a Brown Dwarf companion to the star ζ Delphini.

Brown Dwarfs are objects intermediate to stars and planets in size; they are not large enough to fuse ordinary hydrogen in their cores, but are large enough to fuse the heavier isotope deuterium. These objects are thought to be quite variable in nature, with the largest and warmest resembling small Red Dwarf stars, but with cooler members of the group being more planet-like, and potentially having solid surfaces, planet-like atmospheres and even ice formation on their surface. Many of the Brown Dwarfs so far discovered are companions to true stars, though they are rarer as companions than both secondary stars and planets, with only a little over a hundred such companions observed since the first discovery in 1995. The larger number of companion stars discovered is easily explained, as such bodies tend to be easily visible, but as the number of planets discovered in other stellar systems has risen steadily it would have been expected that the number of Brown Dwarfs (typically larger, brighter and easier to spot than planets) would have kept pace, yet this has not happened.

In a paper published on the arXiv database at Cornell University Library on 30 September 2014, and accepted for publication in the Monthly Notices of the RoyalAstronomical Society, a team of astronomers led by Robert De Rosa of the Schoolof Earth and Space Exploration at Arizona State University and the School of Physics at the University of Exeter describe the discovery of a Brown Dwarf companion to the star ζ Delphini (Zeta Delphini) by the VAST (Volume-limted A-Star) Survey using the Near InfraRed Imager and Spectrometer (NIRI) and ALTitude conjugate Adaptive optics for the InfraRed (ALTAIR) systems on the Gemini North telescope, with additional observations made by the Canada France Hawaii Telescope and the MMT Observatory.

ζDelphini is an A3V star (a blue-white star considerably more massive than the Sun) 220 light years from Earth in the constellation of Delphinus. It is thought to be about 525 million years old with a mass of about 2.5 times that of the Sun and an effective surface temperature of 8336K (compared to 5778K for the Sun). No debris disk has been found around ζ Delphini (visible debris disks are associated with the early stages of planetary formation, though with an age of 525 million years it would be predicted that any such disk in the system would have dissipated) and the star has not been associated with any young stellar group (group of young stars with similar trajectories and ages, thought to share a common origin).

The new companion is named ζ Delphini B, making the original star ζ Delphini A. It is estimated to be between 40 and 55 times as massive as Jupiter, and to have an effective surface temperature of 1550K. ζ Delphini B is currently 912 AU from ζ Delphini A (i.e. 912 times as far from its parent star as the Earth is from the Sun), though it is thought to have an eccentric orbit with an average distance from the star of 907 AU, and an orbital period of about 10 000 years.

The Gemini/NIRI observation of the ζ Delphinisystem obtained on 2010 June 8 showing the location of the heavily saturated ζ DelphiniA, the substellar companion ζ Delphini B (zet Del B) and the seven background objects (BG 1-7) used in the astrometric analysis (indicated by the arrows). The image has been processed through a median filter to reduce the significant amount of scattered light from ζ Delphini A. The orientation and angular scale are given for reference; note that east and west are reversed in sky maps relative to ground maps as one is looking up rather than down, and that the scale is given in arcseconds (“) – the sky is divided into 360˚ (although only 180˚ is ever visible from any point on the Earth), with each degree (˚) divided into 60 arcminutes (‘) and each arcminute divided into 60 arcseconds. De Rosa et al. (2014).

There are currently three theories as to how a star could come to have a Brown Dwarf companion. The Brown Dwarf could potentially form as part of a large circumstellar disk, in a similar way to a planet, though the formation of a ~50 Jupiter-mass object at a distance of over 900 AU is improbable, both because this would require a remarkable amount of matter at the thin outer-edge of the circumstellar disk and because of the timescales that would be required for the object to coalesce (things tend to move slowly in the outer parts of stellar systems, as all motion is essentially driven by the gravity of the star, and the ζ Delphini system is only thought to be 525 million years old), however this possibility cannot be ruled out as it is possible that ζ Delphini B formed much closer to ζ Delphini A, and has subsequently migrated outwards due to gravitational interactions. Secondly it is thought possible that sometimes young pre-stellar cores can be fragmented, producing two bodies rather than one, though this is thought to be an extremely violent process, resulting in two bodies separated by distances measured in thousands of AU rather than hundreds. Finally it is possible that the two bodies formed separately and that ζ Delphini B was subsequently captured by the gravity of ζ Delphini A, though De Rosa et al. calculate that such an occurrence is unlikely, given the weak gravitational force exerted by the star at 900+ AU distances.

See also…

Brown Dwarfs are curious objects, intermediate between stars and planets. They lack the mass to fuse hydrogen in their cores like true stars, but are massive enough to fuse deuterium (a heavy isotope hydrogen, containing one proton and one neutron in its atomic nucleus), unlike planets. Brown Dwarfs therefore emit light in the infrared part of the spectrum, rather than simply reflecting light like a planet; though Brown Dwarfs within...

The KOI-13 system (Kepler Object of Interest system) comprises a pair of A-type White Dwarf stars 1630 light years from Earth, orbiting each to closely to be well differentiated. The larger of these, KOI-13α, has a mass 2.05 times that of the Sun, the smaller, KOI-13β, has...

M Class stars, or Red Dwarfs, are the most abundant stars in the Galaxy, and presumably the Universe. They are small (7.5-60% of the mass of the Sun) and cool (2300-3800 K, compared to 5778 K for our Sun), but can be very long-lived, as they burn their fuel slowly...

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The conservation status of Madagascan Palms.

Madagascar is considered to be one of the world’s biodiversity hotspots. The island has an area of 592 750 km2 and is located in the southern Indian Ocean, giving it a tropical climate with a diverse range of habitats. There is a range of mountains running from the north to the south of the island, which divide it into distinct climatic and environmental bands; the eastern part of the island having a much moister climate dominated by moist tropical forests, while the west of the island is more arid and dominated by dry thorn forests. Madagascar has been separated from all other landmasses since the Cretaceous, and has a unique flora and fauna comprised largely of species found nowhere else.

There are 195 known species of Palms found on Madagascar, of which 192 are known only from the island. 90% of these are restricted to the moist forests on the east side of the island, an environment considered to be particularly at risk; about 75% of these moist forests have been cleared to date and clearance is still ongoing in many areas. Palms are also targeted by humans for a variety of reasons, including for Palm hearts (which are consumed as food), timber for construction and, increasingly, collection for the horticulture industry.

In a paper published in the journal PLoS One on 30 July 2014, Mijoro Rakotoarinivo of the Kew Madagascar Conservation Centre in Antananarivo and John Dransfield, Steven Bachman, Justin Moat and William Baker of the Royal Botanic Gardens at Kew in the UK present a systematic review of the conservation status of the 192 indigenous Malagasy Palm species under the terms of the International Union for the Conservation of Nature’s Red List of Threatened Species; the first such assessment of Malagasy Palms published since 1995.

Rakotoarinivo et al. conclude that of the 192 known indigenous Malagasy Palm species, 61 species are Critically Endangered, 45 species are Endangered, 43 species are Vulnerable, 14 species are Near Threatened and 16 species are of Least Concern. 13 species were found to be Data Deficient; that is to say there was not sufficient information available to include them in the review.

Forest clearance for slash and burn cultivation by smallholder farmers, causing habitat loss for many species, such as Masoala kona (Endangered). William Baker in Rakotoarinivo et al. (2014).

The number of species considered to be at risk (Critically Endangered, Endangered and Vulnerable) has gone up since 1995, however this is in part due to the discovery of 28 new species of Palms since this time, 27 of which are considered to be at risk and 18 Critically Endangered (this is quite common; species with large populations and wide distributions are likely to have been discovered some time ago, so newly discovered species are often in high risk conservation categories); many of the newly described species are known only from very restricted areas, and several from less than 10 species.

Of the 130 species assessed in 1995, 80 have had no change in conservation status, while 32 species are considered to be less threatened than previously and 24 species are considered to be more threatened now than in 1995. While there have been some improvements in the protection of wild Palms in Madagascar, most notably the establishment of the new Système des Aires Protégéesde Madagascar Reserve network, many of the species considered to be at less risk than in 1995 are so considered because fieldwork by conservationists and botanists has discovered new populations of these plants, though 21 of the 32 less threatened species are still considered to be at risk.

Remnant populationsof species such as thisTahin aspectabilis (Critically Endangered), at Analalava, near Mahajanga, in vegetation remnants isolated within anthropogenic landscapes, are at risk fromfire, grazing and other human pressures. John Dransfield in Rakotoarinivo et al. (2014).

Rakotoarinivo et al. conclude that up to 83% of native Malagasy Palm species are currently threatened, making the group particularly threatened even for Madagascar (where 54% of plant species are considered to be threatened, compared to 21.5% of plant species globally). These Palms are at threat primarily due to human activity, particularly the clearing of forests for agriculture and unsustainable harvesting of wild Palms. Rakotoarinivo et al. note that the economic circumstances of Madagascar’s large rural communities are of particular importance to Palm conservation on the island, and that without economic changes that enable this population to change the way they live, forest clearances and unsustainable harvesting are likely to continue, making other conservation measures irrelevant.

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Industrial scale timber extraction began on Borneo in the 1970s and during the period 1980 to 2000 more timber was harvested from Borneo than from Africa and the Amazon Basin combined. In addition much forest has been cleared to make way for monoculture plantations, for the palm oil, rubber and timber industries, as well as being burned in forest fires.  For this reason the island...

Braconid Wasps are small parasitic Wasps which can typically lay several eggs on a large host species (typically another Insect or Spider). The larval Wasps grow inside the host, before emerging to pupate on its surface; unusually for parasitic Wasps the host is not...

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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Partial Solar Eclipse on Thursday 23 October 2014.

A partial Solar Eclipse will occur on Thursday 23 October 2014, visible from most of North America as well as parts of the Russian Far East. The eclipse will occur between 7.35 pm and 11.15 pm GMT, and be visible from most of Canada, the United States and Mexico, and parts of Guatemala, Belize, Cuba, the Bahamas and the Russian Far East.

The area over which the 23 October 2014 partial Solar Eclipse will be visible. Areas in darker grey will be able to observe the entire eclipse, in the lighter grey areas the eclipse will either begin before sunrise or end after sunset, so only part of the event will be visible. HMNautical Almanac Office.

Eclipses are a product of the way the Earth, Moon and Sun move about one-another. The Moon orbits the Earth every 28 days, while the Earth orbits the Sun every 365 days, and because the two Sun and Moon appear roughly the same size when seen from Earth, it is quite possible for the Moon to block out the light of the Sun. At first sight this would seem likely to happen every month at the New Moon, when the Moon is on the same side of the Earth as the Sun, and therefore invisible (the Moon produced no light of its own, when we see the Moon we are seeing reflected sunlight, but this can only happen when we can see parts of the Moon illuminated by the Sun). However the Moon does not orbit in quite the same plane as the Earth orbits the Sun, so the Eclipses only occur when the two orbital planes cross one-another; this typically happens two or three times a year, and always at the New Moon. During Total Eclipses the Moon entirely blocks the light of the Sun, however most Eclipses are Partial, the Moon only partially blocks the light of the Sun.

Although the light of the Sun is reduced during an Eclipse, it is still extremely dangerous to look directly at the Sun.

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A total Lunar Eclipse will occur on 8 October 2014, starting at about 9.15 am GMT. It will be visible across much of the Pacific, as well as eastern parts of the United States and Canada, northeastern Asia and eastern Australia. Part of the eclipse will be visible from remaining areas of the Americas as well as the rest of Australia most of Asia, although in these areas the Moon will either rise part way through the eclipse, or set...

The September Equinox will fall on 23 September 2014, when the day and night will be of equal length in both of the Earth's hemispheres. The Earth spins on its axis at an angle to the plain of the Solar System. This means that the poles of the Earth do not remain at 90° to the Sun, but rather the northern pole is tilted towards the...

At 5.44 pm GMT on Sunday 10 August 2014 the Moon will be at its closest point to the Earth in 2014, at a distance of 356 896 km. 27 minutes later it will officially...

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Tuesday, 21 October 2014

Human remains from the Middle Pleistocene of Normandy.

Early and Middle Pleistocene Human remains are extremely rare in northern Europe, having to date been found only at a single location (Biache-Saint-Vaast) in France, as well as three locations in the UK (Swanscombe, Boxgrove and Pontnewydd) and seven sights in Germany (Sarstedt, Bilzingsleben, Weimar-Ehringsdorf, Maur, Reilingen, Steinheim and Bad Cannstatt).

In a paper published in the journal PLoS One on 8 October 2014, a team of scientists led by Jean-Philippe Faivre of the Unité Mixte de Recherchede la Préhistoireàl’Actuel: Culture, Environnement et Anthropologie at the Université de Bordeaux describe the discovery of Middle Pleistocene Human remains from an additional site in northern France, Tourville-la-Rivière in Normandy, for the first time.

Location of the open-area site of Tourville-la-Rivière and other Northwest European (north to 45˚N and west to 16˚E) contexts, contemporaries of Early and Middle Pleistocene, that have yielded Human remains. Faivre et al. (2014).

The Tourville-la-Rivière site is a gravel quarry in the Seine Valley that has produced traces of Human activity since 1967, but has not previously produced any actual Human remains. Previous finds have included 726 stone tools as well as a wide variety of animal remains, some of which show signs of processing by Humans. The stone tools include numerous Levallois blades but no Levallois cores (rocks from which the blades would have been split off), which has led to the suggestion that the blades were being imported to the site (this is significant as it is thought that the first stone tool users made the tools they needed at the site they used them, then discarded them when they were finished, as is seen to some extent in Chimpanzees; the retaining of tools for later use being a development indicative of more advanced forward planning). Non-Lavallois blades and some non-Lacallois cores have also been discovered at the site, as well as some Rocourt-type tools (which are formed in a slightly different way, producing longer blades). The site has been dated to between 183 000 and 226 000 years old.

The Tourville-la-Rivièresite: General view of the site during excavation. Faivre et al. (2014).

Human remains were discovered at the Tourville-la-Rivière site by Antoine Cottard of the Institut national de recherches archéologiques préventives at the Centre archéologique de Grand Quevilly and Aminte Thomann. The material comprises the left humerus, radius and ulna (arm bones) all being blackened and eroded. The black colouration is probably indicative of having decomposed in standing water.

The Tourville human remains in situ. The posterior and medial surfaces were the first to be made visible for the radial (# 1175) andulnar (# 1176) diaphyses, respectively, while the postero-medial surface of the humeral diaphysis (#1174) and posterior surface of the distal extremity were the first to be exposed. (A)distal extremity of the humerus, posterior face; (B) fragments of the distal portion of the humeral diaphysis.Several elements have since been refitted to the diaphysis; (C) the humeral diaphysis, medial to posteromedial face, proximal extremityto the north-west; D: radius, posterior face, proximal extremity to the north; (E) ulna, medial face, proximal extremity to the north. Dotted lines indicate the alignment of the broken part of the distal and proximal extremities of the ulna and radius. Faivre et al. (2014).

The precise taxonomy of Early and Middle Pleistocene Humans from Europe is debatable, with experts holding differing opinions as to whether Neanderthals should be seen as a different species or just a distinct population of early modern Humans. Whatever their relationship to modern Humans, the group do present a distinctive set of morphological traits which enable their identification as a distinct subset of human remains, presumably with a shared ancestry. Identification of Neanderthals usually depends on examination of the skulls and teeth of specimens, which are not present in the Tourville-la-Rivière material; identification of bones from other parts of the body is harder, as there is considerable overlap between morphologies found in Neanderthals, Modern Humans and other Early Modern Human populations. Nevertheless on this occasion Faivre et al. feel confident in assigning these bones to the Neanderthal group, as their morphology falls within a range seen in 70.5% of Neanderthal specimens, but only 8.8% of other Early Modern Humans and 2.8% of Modern Humans.

The Tourville left upper limb remains. Top: humerus; bottom left: ulna; bottom right: radius. For all the bones: A: anterior view; M:medial view; P: posterior view; L: lateral view. Faivre et al. (2014).

See also…

Ritual use of raptor claws by Neanderthals, 90 000 - 40 000 years ago.
Ritual or symbolic behaviour is generally taken as a sign of cognitive levels comparable to those of modern humans by palaeoanthropologists studying ancient human populations. The earliest signs of this are often taken as the use of red ochre by Neanderthals in Europe and Archaic modern humans in Africa, but some specialists regard this as slightly suspect, since red ochre does have non-ritual applications.

Red ochre is a dye made from the mineral hematite (Fe₂O₃). It's use by ancient humans is generally assumed to be ritual, though modern...
On Tuesday this week (26 July 2011) Bristol University announced the discovery of a carving of a speared reindeer in a cave on the Gower Peninsula. It is thought the carving could be over 14 000 years old and is possibly Britain's oldest known art.
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Stone tools from the Middle to Late Pleistocene of the Nefud Desert.

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. The area is close to the southern extent of the range of the Neaderthals, who occupied much of Europe and West Asia during the Middle Pleistocene, and it is thought that Modern Humans dispersed through the region between about 130 000 and 75 000 years ago. The Nefud Desert has yielded a number of sites from which a variety of stone tools have been collected, however while a variety of Hominid remains have been found in other areas of the Middle East, none have been found from the Nefud, making it hard to assert the identity of the Nefud toolmakers with any confidence.

In a paper published in the journal Quaternary International on 8 October 2014, a team of archaeologists led by Eleanor Scerri of the University of Bordeaux discus the results of a survey of a survey of archaeological sites in the southern Nefud Desert carried out in 2013.

The area studied is currently hyperarid, and covered by a variety of and dune structures. However it is thought to have had a wetter climate at times over the past half million years, with lakes occupying the area at about 410 000 years ago, about 320 000 years ago, about 200 000 years ago, about 125 000 years ago, from about 40 000 to 25 000 years ago and from about 10 000 to about 6000 years ago. During some of these periods it appears likely that significant lakes covered much of the area, but during others it is more likely that smaller ephemeral (temporary) lakes were scattered across the region.

In 2013 Scerri et al surveyed 12 sites in the southern Nefud, five close to the village of Khall Amayshan (numbered KAM 1-4 and 6), two near Al Raba (Rab 3 and 4), two at Khabb Musayyib (KM 1 and 2), one in the T'is al Ghadah Basin (TAG 1), one in the Tayma Wildlife Reserve (WR) and one in the Munasafiyah Basin (HIS 1).

Map of the Middle and Upper Palaeolithic sites found during the Palaeodeserts 2014 survey of the southwestern Nefud. KAM 1e5 refer to Khall Amayshan sites; KM 1e2 andKM-RM refer to the sites at Khabb Musayyib; TAG 1 refers to Ta'is al Ghadah; HIS 1 refers to a site along a line of jibal; RAB 3 and 4 refer to the Al Raba sites; WR refers to the Wildlife Reserve site. Scerri et al. (2014).

The first Khall Amayshan site (KAM 1) was first discovered in 1998 and is thought to date to between 117 000 and 99 000 years ago. The site represents a circular lake which persisted some time, laying down at least 3.24 m of layered marls, silts and sands, from which fossils of a number of freshwater Diatoms have been recovered, providing a reliable guide to both the dates of the deposits and the conditions under which they were laid down. A variety of stone tools have been recovered from these lake deposits.

Exposed lakebed and location of the sampled section at KAM 1. Paul Breeze in Scerri et al. (2014).

Scerri et al. recovered 106 stone artifacts from this site, all being of good quality and most made of quartzite, with some chert objects; the quartzite appears to come from the local region, but the chert is from further afield. Eleven cores (stones from which numerous flakes had been removed) were found, along with numerous flakes. Most were of the Levallois type (a distinctive style of tool making first described from tools from Levallois, a suburb of Paris, in the nineteenth century; flakes are chipped away from the edges of a stone core in a way that leaves it resembling a tortoise shell), which is considered to be Middle Palaeolithic. Scerri et al. suggest that the artifacts were left by toolmakers who were sporadically visiting the lake, and working stone by the lake edge.

Selected artefacts from KAM1. (1) Conjoined Levallois flake with bidirectional flaking pattern; (2) Levallois flake with centripetal flaking pattern; (3) broken Levallois flake,possibly a point, with unidirectional flaking pattern; (4) broken Levallois flake, possibly a point, with bidirectional flaking pattern; (5) Levallois flake with centripetal flaking pattern; (6) centripetally prepared preferential Levallois core; (7) double side retouched point; (8) side retouched flake; (9) refitted single platform core and flake; (10) refitted core management flakes; (11) conjoined blade. Eleanor Scerri in Scerri et al. (2014).

The second Khall Amayshan site (KAM 2) was discovered for the first time during this survey. It yielded only two poorly preserved handaxes from a marl deposit, which were not collected. However the site was recorded for potential further investigation.

The third Khall Amayshan site (KAM 3) was also discovered for the first time during this survey. It produced a small number of Late Palaeolithic artefacts from a Diatom bed. Again these objects were not collected, but the site was identified for later investigation.

Acheulean Handaxes from KAM 3. The handaxes were heavily weathered andabraded, suggesting a long surface exposure. Eleanor Scerri in Scerri et al. (2014).

The fourth Khall Amayshan site (KAM 4) appears to represent an ephemeral lake site, where lakes appeared and disappeared over a long period of time. While these have not yet been accurately dates, the site yielded a total of 1561 artefacts, from several distinct phases of activity, ranging from Acheulean (expand) to Middle Palaeolithic in nature. Some handaxes from the site were made of a distinctive rock with a ‘wood grain’ pattern, which has also been found at the KM sites and KAM 1, but which has yet to be identified.

Artefacts from KAM 4. (1) Side denticulated flake; (2) Point produced using the unidirectional convergent Levallois method; (3) Recurrent centripetal Levallois core; (4) Centripetally prepared preferential Levallois core; (5-6) Handaxes. Eleanor Scerri in Scerri et al. (2014).

The fifth Khall Amayshan site (KAM 6) consisted of lake bed deposits made up of Diatomite with preserved Crayfish burrows, overtopped by gypsum beds (evaporite deposits probably formed as the lake dried up). The site yielded several cores and flakes of the Levallois type, which were not collected, the site being recorded for further investigation later.

The first Al Raba site (RAB 3) comprises an area of about 1.16 km2 of reworked sediments, mostly gypcretes and silts, which also produced Middle Palaeolithic objects; it is unclear if these objects are also reworked. These objects were not collected, but the site was recorded for further investigation.

The second Al Raba site (RAB 4) comprised an area of lake sediments about 1.5 km to the southeast of RAB 3. This also yielded Middle Palaeolithic artifacts, but again these objects were not collected, but the site was recorded for further investigation.

The two Khabb Musayyib sites (KM 1 and KM 2) are a pair of gypsum and marl lakeshore deposits, apparently derived from the remains of a single lake-bed which has otherwise eroded away. These sites have yielded a variety of Early Palaeolithic remains, including small, finely made handaxes, a chopper core and Levallois cores and flakes. A site of material for tool-making was also found at KM 2, with sandstone and quartz cobbles along with further tools.

KM1b (mid ground) and KM2 (background, viewed from the top of KM1a, looking south-east. Paul Breeze in Scerri et al. (2014).

The Khabb Musayyib sites yielded a total of 68 artefacts, mostly made from quartzite, though one handaxe made from high grade chert was also found. The artefacts from the lakeshore at KM2 appear to date from a different period to the artifacts at the material source. 57 objects were obtained from the lakeshore deposits, 40 of these being small, well-made bifaces (cutting tools with two cutting edges), averaging 91 mm in length.

Tools from the lakeshore deposits at KM 2. (1-2) Small finished bifaces; (3) unfinished biface; (4) large finished biface; (5-6) unfished bifaces; (7) discoidal core; (8) denticulated flake. Eleanor Scerri in Scerri et al. (2014).

Artefacts from the second site, KM-2. (1) Micoquian Handaxe with missing tip; (2-3) bifaces; (4-5) Levallois cores. Eleanor Scerri in Scerri et al. (2014).

The T'is al Ghadah Basin site (TAG 1) comprises a lake bottom with several well preserved horizons yielding numerous surface fossils. On top of this series of beds a number of collections of stone tools were found. The fossil remains have been dated from the Early Pleistocene to about 410 000 years ago, while analysis of the uppermost sediments suggest ages of 328 000 to 310 000 years ago. It is unclear if the artifacts found at the site date from this period or are more recent, but if they are then they represent some of the oldest Middle Palaeolithic material found in the Nefud.

76 artefacts were recovered from TAG 1, predominantly from scatter sites in two different areas of the basin. One such scatter site produced a distinctive set of simple cores and flakes, of apparent early Middle Palaeolithic origin made from a pale amber quartzite. Cores from elsewhere in the basin were predominantly of a darker quartzite, with a few chert objects, and comprised small cores and core fragments and flakes. This tool set includes bifaces, discoidal cores, bifacial flakes, Levallois flakes and simple blade cores, suggesting a late Early Palaeolithic or early Middle Palaeolithic origin.

Flakes from TAG 1. (1-5) Retouched flakes; (6) pointed flake; (7) Levallois flake; (8) Retouched flake; (10-13) Discoidal flakes. Eleanor Scerri in Scerri et al. (2014).

The Tayma Wildlife Reserve site (WR) comprises an area of exposed bedrock with eroded channels, with some infill material, leading downwards to an exposed mudflat. The material gathered here was trapped in the erosion channels. Scerri et al. recovered 94 flakes, two bifaces and 35 cores from this site, most made of local rock, but including some quartz, limestone, chert and rhyolite also used. This site is thought to contain material from several phases of occupation, but is of a broadly Middle Palaeolithic origin.

Flakes from the Wildlife Reserve site. (1-5) Single platform and discoidal flakes; (6-8) Levallois flakes; (9) Retouched Levallois point, probably recycled; (10) Levallois flake; (11) large, cortical flakes. Eleanor Scerri in Scerri et al. (2014).

Cores from the Wildlife Reserve site. (1-2) Centripetally prepared preferential Levallois cores; (3) recurrent centripetal Levallois core; (4) Single platform core; (5) bidirectional Levallois point core; (6-7) discoidal cores; (8) single platform core; (9) multiple platform core; (10-11) bifaces. Eleanor Scerri in Scerri et al. (2014).

The Munasafiyah Basin  site (HIS 1) comprised a scattered Palaeolithic site along the lower slopes of a jibal (line of rocky hills). The site featured considerable rock art, as well as artefacts of Early and Middle Palaeolithic origin, including handaxes, bifaces, Levallois cores and flakes, débordant flakes, core tablets and other material. All appeared to be made of local quartzite, suggesting the toolmakers were using scree slopes at the foot of the jebel as a source of material. None of the material was collected, but the site was marked for further investigation.

The sites yielded a great diversity of Late Pleistocene material, but very little from the Holocene, suggesting that conditions were considerably more favourable in the Nafud then. The Early Palaeolithic material suggests a long period of continuous occupation of the area, associated with fairly stable lakes, which existed for long periods of time. The Middle Palaeolithic material is more scattered and suggests more temporary occupation, associated with ephemeral lakes, which were not always present. Scerri et al. suggest that the area was occupied repeatedly from neighbouring areas, such as Jordan and the Sinai, when conditions were favourable, then abandoned again when the lakes dried up.

See also… Dating the Toba Eruption.                                    Sometime between 69 000 and 77 000 years ago a large volcano occupying the site of the current Lake Toba on northern Sumatra underwent what is believed to have been the largest volcanoc eruption of the Quaternary Period, covering much of south Asia in around 15 cm of ash, and probably causing... Toolmaking in the northeastern Thar Desert 95 600 years ago.                                                                 The Thar Desert covers over  200,000 km² of land in the northwest part of the Indian Subcontinent, straddling the border between Pakistan and India. It marks the... 20 000 year old stone huts from Kharaneh in Eastern Jordan.                                                                       The earliest stone structures are generally associated with the Epipalaeolithic Natufian culture of Southwest Asia (the term Epipalaeololithic applies to cultures outside the extent of the last glaciation that showed the same...
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A giant agglutinated Foraminiferan from the Western Mediterranean.

Foraminiferans are Amoeba-like single-celled organisms found either free-floating or attached to surfaces in marine ecosystems. Many build ornate tests (shells) from calcium carbonate, and planktonic forms are widely used in biostratigraphy (the use of small fossils to date sedimentary rocks), but others lack the ability to produce their own biominerals, and instead construct protective coverings by cementing together other items.

In a paper published in the journal Zootaxa on 10 June 2013, a team of scientists led by Manuel Maldonado of the Centro de Estudios Avanzados deBlanes describe a new species of agglutinated Foraminiferan from the Seco de Palos seamount in the Western Mediterranean.

The new species is placed in the genus Spiculosiphon, and given the specific name oceana, in honour of the non-profit organization for ocean conservation OCEANA, which was responsible for the collection of the samples from which the species is described. Spiculosiphonoceana lives attached to a substrate by a long stalk, both the stalk and the main body being covered by agglutinated Sponge spicules, though these are arranged laterally in a slight spiral around the stalk but radiate out from the body.

(A) General view of the Spiculosiphon oceana. (B) Detail of capitate region of the holotype, showing the globelike, central structure and the radiating tracts of spicules. Maldonado et al. (2013).

Spiculosiphon oceana is a giant by Foraminiferan standards, reaching in excess of 4 cm in length. It is only the second species assigned to the genus Spiculosiphon; the first species, Spiculosiphon radiata is also large, but less so than Spiculosiphon oceana, reaching only about 2 cm. This species was described from specimens collected off the coast of Norway in 1964.

Maldonado et al. note that both species of Spiculosiphon show remarkable convergent evolution with some small species of Carnivorous Sponge, using scavenged Sponge spicules to build a body very similar in form to the Sponge; both organisms then trapping relatively large prey and dissolving it externally.

(A) View of the carnivorous sponge Asbestopluma hypogea soon after trapping a small Copepod. The sponge isdisplaying the spiny-headed morphology, which is typical after a period of starvation in order to maximize the chances of new prey capture. (B) View of the capitate region of Spiculosiphon oceana for a comparison with the body shape of the Carnivorous Sponge. Maldonado et al. (2013).

Maldonado et al. further observe that many agglutinated Foraminiferans appear to have a preference for Sponge spicules when incorporating material into their tests, while tending to reject other sources of biogenic silica such as Diatom shells. They suggest that this may be linked to the ancient nature of the group; the earliest Foraminiferans are thought to have appeared about 770 million years ago, in the Middle Cryogenian Period (about the same time as the earliest Sponges), while the Agglutinated Foraminiferans are thought to have arisen in the late Ediacaran or early Cambrian, about the same time as the earliest Siliceous Sponges (Sponges producing spicules made of silica). The earliest Diatoms appeared in the Early Jurassic, about 199 million years ago, by which time Agglutinated Foraminiferans had evolved to use Sponge spicules wherever possible.

That said, they also acknowledge that while Sponge spicules and Diatom tests are generally considered to be chemically identical, Sponge spicules do persist for much longer in seawater without dissolving (which clearly has advantages when using recycled material as a construction material), leading Maldonado et al. to suggest their may be different trace elements or compounds in the two materials, which both contributes to the more durable nature of the Sponge spicules and is detectable to the Foraminiferans.

SEM micrograph of stalk. (Tightly packed needle-like spicule fragments, with no obvious cement betweenthem. Some debris (d) has flocculated on the spicules. Note that the silica of some of the oldest spicules started dissolving, asindicated by the occurrence of tiny cavities and pits (p) at their surface. Dissolution cavities are to be distinguished fromaccidental breakages (b) caused to the stalk during collection or laboratory manipulation. Maldonado et al. (2013).

Maldonado et al. also record patches of colour on the stalk of Spiculosiphon oceana which appear to derive neither from the mineralogy of the spicules nor any fouling organism living external to the stalk. Instead they suggest this may be caused by photosynthetic symbionts growing inside the stalk (beneath the translucent spicules). Other species of Agglutinated Foraminiferans have been recorded to host a variety of Dinoflagellates, Diatoms, unicellular Chlorophytes (Green Algae), unicellular Rhodophytes  (Red Algae) and Cyanobacteria; the colour of the markings on the Spiculosiphon oceana stalks tending to suggest Dinoflagellates, Rhodophytes, or Cyanobacteria might be present, though they were unable to confirm this.

The stalk in showing a region in which the translucent spicule wall gets a brownish to purplish coloration. Maldonado et al. (2013).

Finally Maldonado et al. report the presence of a Calcareous Foramiferan test attached to the stem of one of the specimens (presumably the remains of a past meal) and not that both this test and the adjacent area of the stem show raised levels of the element tellurium. This is a very rare element, and has never been reported in any Foraminiferan before (nor many other organisms). It is unclear whether the source of this tellurium is the Calcareous or the Agglutinated Foraminiferan, nor exactly what biological process it could have been used in.

(C) Detail of a calcareous foraminifer (f) externally attached to the wall of one ofthe collected stalks. Note that a triaene (t) has been incorporated into the test and that some debris (d) hasflocculated on the stalk. Maldonado et al. (2013).

See also…

Golden Algae (Chrysophyceae) are photosynthetic eukaryotic microbes (i.e. single celled organisms that posses cell nuclei similar to those found in the cells of animals and plants, but unlike bacteria which do not), found throughout the world, predominantly in fresh water. The group is mostly poorly studied, with the exception of a few species which are toxic to Fish. Four new species of fossil Diatom from the western United States.                                              Diatoms are single celled algae related to Kelp and Water Moulds. They are encased in silica shells with two valves. During reproduction the cells divide in two, each of which retains one valve of the shell, growing a new opposing valve, which is slightly smaller and fits flush within the older valve. This means that the Diatoms grow smaller with each new generation, until they... The oldest animals - Pre-Ediacaran Sponges from Namibia(?)                                                             Sponges are curious creatures. They are considered to be animals as they are multicellular and some of them have fixed body shapes, however they show no cell differentiation, and can be broken down into individual cells (by, for example, forcing them through a sieve) and they will re-assemble themselves without apparent ill-effect. In some ways they are more like colonial protists than true animals. Biologists have long regarded them as the most primitive animal...

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