Fifty-million-year-old fossil beetles that fed only on palm seeds are giving biologists new information about ancient climates. Credit: Image courtesy of Simon Fraser University
Fifty-million-year-old fossil beetles that fed only on palm seeds are giving Simon Fraser University biologists Bruce Archibald and Rolf Mathewes new information about ancient climates.
According to their research, published online this week in The Proceedings of the National Academy of Sciences, these fossil beetles indicate that during a period of global warming in the geological past, there were mild, frost-free winters extended even in the uplands of ancient western North America.
Working with co-authors Geoffrey Morse of the University of San Diego, California, and David Greenwood of Manitoba’s Brandon University, researchers used fossil beetles to determine winter temperatures where they couldn’t place a thermometer — in the 50-million-year-old uplands of British Columbia and Washington.
The key to their study was finding a particular group of beetles that only feed on palms.
“The natural distribution of palms is limited today to regions without significant frost days, which their seeds and seedlings can’t survive,” Archibald explains. “A cooler upland with palms indicates a specific climate type, where a temperate average yearly temperature — rather like Vancouver today — had warmer winters where palms can complete their lifecycles.”
But since detecting palm fossils is difficult, the research duo developed a new technique — they used the beetle fossils to test for the palms’ presence.
Understanding more about these temperate, yet mild winter climates by looking to the deep past may help show how natural communities are impacted by climate change, says Archibald. “We see this happening today in significant ways — warm the winters a little, and you get big changes, such as the explosion of mountain pine beetle populations that strongly affect forests and the people and economies that depend on them.
“Using the fossil record to understand climates of the deep past that had significant similarities to climates that we are now encountering may help forearm us with knowledge that will be important to our future as we increasingly experience the effects of global warming.”
The team’s research was made possible by funding from the Natural Sciences and Engineering Research Council of Canada.
Note : The above story is based on materials provided by Simon Fraser University.
Vertebrate paleontologist Richard Hulbert Jr. displays the holotype fossil specimen of a lower jaw of a 5-million-year-old saber-toothed cat, Rhizosmilodon fiteae, one of 103 new species Florida Museum researchers described in 2013. Florida Museum of Natural History photo by Jeff Gage
A 5-million-year-old saber-toothed cat, the world’s oldest grape and a bizarre hermit crab were among more than 100 new species discovered by University of Florida scientists last year.
Driven in part by the urgency to document new species as natural habitats and fossil sites decline due to human influences, researchers from the Florida Museum of Natural History, located on the UF campus, described 16 new genera and 103 new species of plants and animals in 2013, with some research divisions anticipating higher numbers for 2014.
An online search shows the only other major research institution reporting similar information is the California Academy of the Sciences, which described 91 new species in 2013 and has averaged 115 per year since 2009.
“Traditionally this isn’t a number many research institutions have tracked,” said Florida Museum Director Douglas Jones. “But the extra emphasis on biodiversity due to degradation of natural habitats and accelerating extinction rate of plants and animals worldwide has placed a higher emphasis on researchers documenting and describing new species before they disappear.”
UF researchers discovered species from more than 25 countries on four continents, including 35 fossil crustaceans, 24 Lepidoptera, 17 plants (11 fossils), eight mollusks, two fossil mammals and one fossil bird, among others. Thirty-one additional species were identified in the museum’s collections by visiting researchers.
Don Davis, curator of Lepidoptera at the Smithsonian Institution’s National Museum of Natural History, said the Florida Museum has actively pursued the goals of all natural history museums, including discovering new organisms to better understand the current distributions and history of all life.
“The scientists there are providing not only new knowledge for a broad range of organisms, but also an excellent, well-documented specimen database for all future researchers in natural history,” Davis said.
Scientists often happen upon new species while working in museum collections or exploring in the field, but recent museum biodiversity projects and collaborations have focused on discovering as many new species as possible.
Museum scientists utilized advanced taxonomic methods during recent biodiversity survey projects, including DNA bar coding, a process that uses a genetic marker to identify if an organism belongs to a particular species. Some of the new species discovered during these surveys prove rare discoveries still occur.
For example, during an international effort to document all animals and plants living on and in the waters surrounding the island of Moorea in French Polynesia, Florida Museum invertebrate zoology curator Gustav Paulay dredged from the deep sea a new hermit crab that exemplifies a rarely documented process in which hermit crabs move out of their shells and harden their bodies to resemble true crabs. Patagurus rex has a broad, armored body with pointy spines and long legs connected to large claws — making it one of the most distinctive hermit crabs discovered in decades, Paulay said.
“There is this idea that we can grab a field guide and work out there as scientists,” Paulay said. “But for large chunks of the world, those resources don’t exist and the science that would support those resources is just not there.”
This is especially true for museum scientists studying some of Earth’s smallest species in remote jungles of the Congo and isolated areas of Hawaii.
Florida Museum assistant curator of Lepidoptera Akito Kawahara said new species of insects sometimes lead to powerful discoveries that affect other fields, including agriculture and medicine.
“Future research will include the investigation of a potential new species of moth in Hawaii that appears to delay plant aging by altering the process of plant senescence (aging) in leaves,” he said. “This moth could have potential for improving agriculture and extending the shelf life of some foods.”
Last year, many scientists looked for new species from the past. Museum scientists described 56 new species of fossil plants and animals. Among these, the world’s oldest-known grape species, Indovitis chitaleyae, discovered in 2005 and described in 2013, pushed the record of the Vitaceae (grape) family into the Late Cretaceous, about 66 million years ago.
Florida Museum vertebrate paleontology collections manager Richard Hulbert described the 5-million-year-old fossils of Rhizosmilidon, a carnivorous saber-toothed cat from the same lineage as the famous Smilodon fatalis from the La Brea Tar Pits of Los Angeles.
“Today’s species represent only about 1 percent of life that ever existed,” said Bruce MacFadden, Florida Museum curator of vertebrate paleontology. “It is important to understand the other 99 percent of biodiversity that once inhabited the planet, because knowledge of the kinds of plants and animals that lived here in the past provide us with a framework for understanding today’s ecosystems.”
Note : The above story is based on materials provided by University of Florida.
Chemical Formula: Pb2(SO4)O Locality: Susanna Mine, Leadhills, Lanarkshire, Scotland. Name Origin: Named for the locality
Lanarkite is a mineral, a form of lead sulfate with formula Pb2(SO4)O. It was originally found at Leadhills in the Scottish county of Lanarkshire, hence the name. It forms white or light green, acicular monoclinic prismatic crystals, usually microscopic in size. It is an oxidation product of galena.
History
Discovery date : 1832 Town of Origin : MINE SUSANNA, LEADHILLS, LANARKSHIRE Country of Origin : ECOSSE
Optical properties
Optical and misc. Properties : Transparent to Translucent Refractive Index: from 1,92 to 2,03 Axial angle 2V : ~60°
The new kind of dinosaur dwarfs even the Argentinosaurus, the previous largest contender. Photograph: Guardian
Paleontologists in Patagonia, southern Argentina on Friday announced they have unearthed a 90-million-year-old fossil of what they claim is the largest dinosaur found to date.
“It’s the largest example ever found,” said Ruben Cuneo, director of the Feruglio Museum of Trelew, a city founded by Welsh settlers in the 1860s.
The new kind of dinosaur dwarfs even the Argentinosaurus, the previous largest contender. It is a 40-metre (130-foot) long sauropod discovered in farmland about 260km (160 miles) from the town of Trelew.
The dinosaur weighed about 80 tons, the equivalent of 14 grown elephants, said the museum director. A complete skeleton was found in a field discovered by a farm worker last year, where up to seven such complete skeletons are believed to exist, in the locality of El Sombrero.
“It’s like two trucks with a trailer each, one in front of the other, and the weight of 14 elephants together,” said José Luis Carballido, the Argentinian paleontologist who led the dig. “This is a real paleontological treasure. There are plenty of remains and many were nearly intact, which is unusual.”
Note : The above story is based on materials provided by Uki Goni in Buenos Aires for theguardian
Map showing schematically the distribution of the three volcanoes now thought to have made up the region of O’ahu, Hawai’i. From oldest to youngest these are the Ka’ena, Wai’anae, and Ko’olau Volcanoes. Upper panel: bold dashed lines delineate possible rift zones of the three volcanoes; also shown are the major landslide deposits around O’ahu. The lower panel shows how the three volcanic edifices overlap. Credit: J. Sinton, et al., UH SOEST
Researchers from the University of Hawai’i — Mānoa (UHM), Laboratoire des Sciences du Climat et de L’Environment (France), and Monterey Bay Aquarium Research Institute recently discovered that O’ahu actually consists of three major Hawaiian shield volcanoes, not two, as previously thought. The island of O’ahu, as we know it today, is the remnants of two volcanoes, Wai’anae and Ko’olau. But extending almost 100 km WNW from Ka’ena Point, the western tip of the island of O’ahu, is a large region of shallow bathymetry, called the submarine Ka’ena Ridge. It is that region that has now been recognized to represent a precursor volcano to the island of O’ahu, and on whose flanks the Wai’anae and Ko’olau Volcanoes later formed.
Prior to the recognition of Ka’ena Volcano, Wai’anae Volcano was assumed to have been exceptionally large and to have formed an unusually large distance from its next oldest neighbor — Kaua’i. “Both of these assumptions can now be revised: Wai’anae is not as large as previously thought and Ka’ena Volcano formed in the region between Kauai and Wai’anae,” noted John Sinton, lead author of the study and Emeritus Professor of Geology and Geophysics at the UHM School of Ocean and Earth Science and Technology (SOEST).
In 2010 scientists documented enigmatic chemistry of some unusual lavas of Wai’anae. “We previously knew that they formed by partial melting of the crust beneath Wai’anae, but we didn’t understand why they have the isotopic composition that they do,” said Sinton” Now, we realize that the deep crust that melted under Waianae is actually part of the earlier Ka’ena Volcano.”
This new understanding has been a long time in the making. Among the most important developments was the acquisition of high-quality bathymetric data of the seafloor in the region. This mapping was greatly accelerated after UH acquired the Research Vessel Kilo Moana, equipped with a high-resolution mapping system. The new data showed that Ka’ena Ridge had an unusual morphology, unlike that of submarine rift zone extensions of on-land volcanoes. Researchers then began collecting samples from Ka’ena and Wai’alu submarine Ridges. The geochemical and age data, along with geological observations and geophysical data confirmed that Ka’ena was not part of Waianae, but rather was an earlier volcanic edifice; Wai’anae must have been built on the flanks of Ka’ena.
“What is particularly interesting is that Ka’ena appears to have had an unusually prolonged history as a submarine volcano, only breaching the ocean surface very late in its history,” said Sinton. Much of our knowledge of Hawaiian volcanoes is based on those that rise high above sea level, and almost all of those formed on the flanks of earlier ones. Ka’ena represents a chance to study a Hawaiian volcano that formed in isolation on the deep ocean floor.
Despite four different cruises and nearly 100 rock samples from Ka’ena, researchers say they have only begun to observe and sample this massive volcanic edifice. While this article was in press, SOEST scientists visited Ka’ena Ridge again — this time with the UH’s newest remotely operated vehicle, ROV Lu’ukai — and collected new rock samples from some of its shallowest peaks. With these new samples Sinton and colleagues hope to constrain the timing of the most recent volcanism on Ka’ena.
Note : The above story is based on materials provided by University of Hawaii ‑ SOEST.
Chemical Formula: (Ca,Na)[Al(Al,Si)Si2O8] Locality: Labrador peninsula, Canada. Name Origin: Named after its locality.Labradorite ((Ca,Na)[Al(Al,Si)Si2O8]), a feldspar mineral, is an intermediate to calcic member of the plagioclase series. It is usually defined as having “%An” (anorthite) between 50 and 70. The specific gravity ranges from 2.68 to 2.72. The streak is white, like most silicates. The refractive index ranges from 1.559 to 1.573. Twinning is common. As with all plagioclase members, the crystal system is triclinic, and three directions of cleavage are present, two of which form nearly right angle prisms. It occurs as clear, white to gray, blocky to lath shaped grains in common mafic igneous rocks such as basalt and gabbro, as well as in anorthosites.
Occurrence
The geological type area for labradorite is Paul’s Island near the town of Nain in Labrador, Canada. It has also been reported in Norway and various other locations worldwide.
Labradorite occurs in mafic igneous rocks and is the feldspar variety most common in basalt and gabbro. The uncommon anorthosite bodies are composed almost entirely of labradorite. It also is found in metamorphic amphibolites and as a detrital component of some sediments. Common mineral associates in igneous rocks include olivine, pyroxenes, amphiboles and magnetite.
History
Discovery date: 1780 Town of Origin : ILE DE PAUL, LABRADOR, NEWFOUNDLAND Country of Origin : CANADA
Optical properties
Optical and misc. Properties : Translucent to transparent Refractive Index: from 1,55 to 1,57 Axial angle 2V: 78-87°
Physical Properties
Cleavage: {001} Perfect, {010} Good, {110} Distinct Color: Colorless, Gray, Gray white, White, Light green. Density: 2.68 – 2.71, Average = 2.69 Diaphaneity: Translucent to transparent Fracture: Uneven – Flat surfaces (not cleavage) fractured in an uneven pattern. Hardness: 7 – Quartz Luminescence: Non-fluorescent. Luster: Vitreous (Glassy) Streak: white
Aerial photo of the San Andreas Fault in the Carrizo Plain, northwest of Los Angeles. Credit: Wikipedia.
Seismologists Emily Brodsky and Thorne Lay with the University of California have gone out on a limb of sorts by publicly wondering if it might be possible to predict the largest types of earthquakes by studying foreshock patterns and characteristics. Together they’ve published a Perspective piece in the journal Science, questioning the traditional belief in the earth sciences field that it’s impossible to predict earthquakes of any kind and likely will always be that way.
Earthquakes are impossible to predict, at least for now, because they don’t behave the same way before they occur. Sometimes there are foreshocks, sometimes not, sometimes animals seem to sense something is up, other times they don’t. There are just no discernible patterns that could be used as a sign of an impending quake. But, the research duo suggest, that doesn’t mean there couldn’t be, especially for special types of quakes—those that lie along subduction zones.
Brodksy and Lay point out that foreshocks occurred along just such a subduction zone prior to the earthquake that rocked Chile this past April. They note also that a very similar pattern occurred just prior to the massive 9.0 quake that shook Japan three years ago. They acknowledge that similar small quake clusters also occur along fault lines that never result in earthquakes, which of course, is why they haven’t been used to predict earthquakes. It’s for this reason that the two are calling for better monitoring systems. Currently there are few pressure sensors permanently installed along major subduction zones, due to the fact that most are along the ocean floor. They suggest that if pressure sensors were installed and data stored in a database, it might be that clues would reveal themselves. Perhaps, they propose, foreshocks behave in certain ways before a big quake that differ from small quake clusters not related to a bigger event. The only way to find out, they say, is to put in sensors.
Governments big and small have been reluctant to install such sensors because of the huge cost involved—adding them along just one coast could cost billions of dollars—an investment that has no certainty of paying off. Thus, it’s doubtful that one paper by a pair of researchers is likely to cause any major changes to the status quo, though it might cause some in the scientific community to begin to question what is possible and what isn’t as it pertains to predicting earthquakes—and that might be all the two authors are really trying to achieve.
More information: Recognizing Foreshocks from the 1 April 2014 Chile Earthquake, Science 16 May 2014: Vol. 344 no. 6185 pp. 700-702. DOI: 10.1126/science.1255202
Note : The above story is based on materials provided by Phys org
Adding iron to the Southern Ocean may not have the climate benefits that advocates of geoengineering have hoped for, a new study suggests.
The theory is to fertilise plankton so they absorb more carbon from the atmosphere and thereby slow down climate change. But researchers found that natural ocean circulation patterns mean most of the carbon probably wouldn’t stay put for long enough for a significant effect on the climate.
Simulations show that even if this method succeeds in absorbing carbon from the atmosphere and sinking it a kilometre beneath the Antarctic waters, currents may mean it only stays there for a few decades.
‘This adds to the evidence that iron fertilisation is never going to be the one solution to the problem of climate change, though there are still a few places it could be useful,’ says Josie Robinson, a PhD student at the University of Southampton and National Oceanography Centre and lead author of the paper, which appears in Geophysical Research Letters. ‘Even if all the problems that have already been pointed out with it were somehow solved, we’ve shown that ocean circulation will limit any benefits.’
Robinson and her co-authors used a high-resolution 3D model of ocean circulation to simulate the movement of carbon that had been added to the Southern Ocean around Antarctica over the course of a century. By the end of that time, two thirds of the carbon had returned to the surface – on average, it took just under 38 years, far less than would be needed for any real effect on the climate.
So-called ocean iron fertilisation (OIF) has been seen as a strong candidate for geoengineering – modifying some aspect of the land, ocean or atmosphere to soften the blow of global warming. It would involve feeding iron into parts of the ocean where its absence is the major factor limiting plankton growth – that is, where other vital nutrients are plentiful but iron is scarce.
Filling this gap could create huge blooms of plankton as these tiny marine plants feast on the sudden banquet, absorbing large amounts of carbon from the air. When the plankton die, would-be-geoengineers hope this carbon will sink down with their bodies and be trapped for millennia in the mud of the seabed, where it can’t affect the climate. The Southern Ocean is one of the biggest iron-deficient areas on Earth, so it’s been a popular candidate for iron fertilisation.
The idea seems plausible, but scientists have increasingly been asking tough questions. Some have pointed out that much of the carbon absorbed by the plankton won’t make it to the seabed; instead, it will decompose on the way down and come right back to the surface to be released to the atmosphere.
The new study goes one step further by looking at the problem from the perspective of a physical oceanographer rather than a marine biologist or biogeochemist. They started out from the assumption that these problems have been solved, so that carbon from a plankton bloom has somehow got down to a kilometre beneath the surface; they then asked how long it would stay there.
‘Other studies have looked at ocean circulation alongside marine biology, interactions between the sea surface and the atmosphere, and lots of other things,’ says Robinson. ‘We just concentrated on the ocean circulation, which meant we could use a much higher-resolution model than they could, and that gives us a much better understanding of how carbon would behave after reaching the deep ocean.’
It turns out that some of the very factors that make the Southern Ocean an attractive target for iron fertilisation also mean this probably wouldn’t have much lasting benefit. Water that’s rich in nutrients other than iron wells up here from the deep sea to the surface, and it’s this that means plankton only need a little iron to form large blooms. But these upwelling currents also pump deep carbon back into shallow waters where it can escape into the air.
Robinson says the research shows the importance of considering ocean circulation in assessing these kinds of proposal. ‘A lot of the discussion has centred on the Southern Ocean, but from a physical oceanographer’s point of view it’s about the worst possible place to hide carbon,’ she comments.
She adds that although the case for iron fertilisation in the Southern Ocean is weakened, the technique may still have some possibilities elsewhere – for example, the north Pacific is one potential target, with iron-poor waters and much less upwelling of water from the ocean depths.
An alternative option may be to move away from the idea of fertilisation with iron, focusing instead on adding other elements such as nitrogen or phosphorus to nutrient-poor waters where there’s very little upwelling and so a much better chance of keeping carbon down for long enough to have a significant effect on the climate. This could be more expensive than adding iron, but then letting climate change run rampant wouldn’t be cost-free either.
More information: “How deep is deep enough? Ocean iron fertilization and carbon sequestration in the Southern Ocean.” J. Robinson, E. E. Popova, A. Yool, M. Srokosz, R. S. Lampitt and J. R. Blundell. Geophysical Research Letters, Volume 41, Issue 7, pages 2489-2495, 16 April 2014. DOI: 10.1002/2013GL058799
Video
Note : The above story is based on materials provided byPlanetEarth Online
Chemical Formula: Al2(SiO4)O Locality: Common world wide. Name Origin: From the Greek kyanos = “blue.”
Kyanite, whose name derives from the Greek word kuanos sometimes referred to as “kyanos”, meaning deep blue, is a typically blue silicate mineral, commonly found in aluminium-rich metamorphic pegmatites and/or sedimentary rock. Kyanite in metamorphic rocks generally indicates pressures higher than four kilobars. Although potentially stable at lower pressure and low temperature, the activity of water is usually high enough under such conditions that it is replaced by hydrous aluminosilicates such as muscovite, pyrophyllite, or kaolinite. Kyanite is also known as disthene, rhaeticite and cyanite.
Kyanite is a member of the aluminosilicate series, which also includes the polymorph andalusite and the polymorph sillimanite. Kyanite is strongly anisotropic, in that its hardness varies depending on its crystallographic direction. In kyanite, this anisotropism can be considered an identifying characteristic.
Occurrence
Kyanite occurs in gneiss, schist, pegmatite, and quartz veins resulting from high pressure regional metamorphism of principally pelitic rocks. It occurs as detrital grains in sedimentary rocks. It occurs associated with staurolite, andalusite, sillimanite, talc, hornblende, gedrite, mullite and corundum.
Kyanite occurs in Manhattan schist, formed under extreme pressure as a result of the two landmasses that formed supercontinent Pangaea.
Physical Properties
Cleavage: {100} Perfect, {010} Imperfect Color: Blue, White, Gray, Green, Black. Density: 3.56 – 3.67, Average = 3.61 Diaphaneity: Translucent to transparent Fracture: Brittle – Generally displayed by glasses and most non-metallic minerals. Hardness: 4-7 Luminescence: Non-fluorescent. Luster: Vitreous – Pearly Streak: white
The area between the Eastern Goldfields and the sea, has been inundated with seawater several times over the past 60 million years. Credit: Geoff Crisdale
A Greenfields exploration has confirmed that present-day Kalgoorlie is close to an ancient coastline.
Geologist Ignacio Gonzalez-Alvarez says the Albany-Fraser Orogen, between the Eastern Goldfields and the sea, has been inundated several times over the past 60 million years.
He says the Yilgarn Craton, by contrast, was deformed by ancient river systems.
“[In] the Albany-Fraser Orogen, [the] main landscape evolution was controlled by transgression-regressions whereas in the Yilgarn Craton [it] was mainly controlled by fluvial systems,” he says.
As a result, the Albany-Fraser Orogen’s bedrock retains the form of countless islands, now mostly buried under regolith (soil and other loose material) up to 100m deep.
“Most of the cover … has been severely affected by transgressions and regressions during the last 60million years,” he says
“And that variation in the sea level has brought marine sediments very much into the continent up to almost Kalgoorlie.”
Although much of the Orogen’s regolith contains marine sediment, he says geochemical analysis of surface material often gives a poor understanding of the underlying geology.
Explorers paid very little attention to the Orogen until recent discoveries of gold (Tropicana project 400km northeast of Kalgoorlie) and copper-nickel (Nova project in the Fraser Range east of Norseman).
The two finds prompted the Orogen’s first extensive exploration, by UWA and CSIRO scientists.
They began to study the Orogen by driving from inland towns like Manjimup, Kojinup and Kalgoorlie towards the coast, stopping frequently to record elevations and take samples for geochemical analysis.
“That sedimentary dynamic or that transgression-regression environment was mainly featured by islands and estuaries and that poses quite a complication,” he says.
“We don’t have a straight line for the coast.”
They then conducted detailed studies at Salmon Gums, Woodline, Beachcomber and Neale, to define exploration protocols which help define proxies for basement geochemistry on the surface.
Dr Gonzalez-Alvarez says regolith sampled on top of the buried islands – which is largely formed by weathering – gives a more reliable indication of bedrock mineralisation.
On the other hand regolith covering the former seabed leads to more ambiguous readings.
“Some of the parts of the Albany-Fraser were not under sea water and that’s interesting in itself because it means that [for] those islands … many of the protocols from the Yilgarn Craton for exploration should be very useful.
He says mapping the islands in a comprehensive survey should open the Orogen up to profitable mineral exploration.
Dr Gonzalez-Alvarez is a senior research scientist at CSIRO, Earth Science and Resource Engineering, Minerals Down Under Flagship, Perth WA.
He and colleagues are yet to publish a paper of their study. You can see his PowerPoint here.
Note : The above story is based on materials provided by Science Network WA
Photographs and half-tone drawings of the anterior caudal vertebrae of Leinkupal laticauda, gen. n. sp. n. (MMCH-Pv 63). Caudal 1-2 in (A) lateral and (B) posterior views. Caudal 7 in (C) lateral and (D) anterior views (reversed). Abbreviations: pf, pneumatic fossa; podl, postzygodiapophyseal lamina; poz, postzygapophysis; prdl, prezygodiapophyseal lamina; prsl, prespinal lamina; prz, prezygapophysis; sprl, spinoprezygapophyseal lamina; spol, spinopostzygapophyseal lamina; tp, transverse process. Scale bar equals 10 cm. Credit: Pablo A. Gallina et al. A Diplodocid Sauropod Survivor from the Early Cretaceous of South America. PLoS ONE, 2014; DOI: 10.1371/journal.pone.0097128
The discovery of a new sauropod dinosaur species, Leinkupal laticauda, found in Argentina may be the first record of a diplodocid from South America and the youngest record of Diplodocidae in the world, according to results published May 14, 2014, in the open access journal PLOS ONE by Pablo Gallina and colleagues from the Fundación Azara (Universidad Maimónides), and Museo E. Bachmann, in Argentina.
Diplodocids are part of a group of sauropod dinosaurs known for their large bodies, as well as extremely long necks and tails. Scientists have identified a new diplodocid sauropod from the early Cretaceous period in Patagonia, Argentina — the first diplodocid sauropod discovered in South America.
Though the bones are fragmentary, scientists found differences between this species and other diplodocid species from North American and Africa in the vertebrae where the tail connects to the body.
These differences suggest to the authors that it may warrant a new species name, Leinkupal laticauda.
Additionally, since Leinkupal laticauda apparently lived much later than its North American and African cousins, its existence suggests that the supposed extinction of the Diplodocidae around the end of the Jurassic or beginning of the Cretaceous period didn’t occur globally, but that the clade survived in South America at least during part of the Early Cretaceous.
Note: The above story is based on materials provided by PLOS.
Chemical Formula: MgB3O3(OH)5·5H2O Locality: Inder, Kazakhstan. Name Origin: Named for Nikolai S. Kurnakov (1860-1941), Russian mineralogist.Kurnakovite is a hydrated borate mineral with the chemical composition MgB3O3(OH)5·5H2O. It is a member of the inderite group and is a triclinic dimorph of the monoclinic inderite.
Discovery and occurrence
Kurnakovite, was first described by Godlevsky in 1940 for an occurrence in the Inder borate deposits in Atyrau Province, Kazakhstan, and is named for Russian mineralogist and chemist Nikolai Semenovich Kurnakov (1860–1941).
In addition to the type locality in Kazakhstan, kurakovite has also been reported from the Zhacang-Caka brine lake, Tibet; the Kirka borate deposit, Kiitahya Province, Turkey; the Kramer borate deposit, Boron, Kern County, California; Death Valley National Park, Inyo County, California; and the Tincalayu borax deposit, Salar del Hombre Muerto, Salta Province, Argentina.
History
Discovery date : 1940 Town of Origin : GIS. INDER, KAZAKHSTAN Country of Origin : RUSSIE ex-URSS
Optical properties
Optical and misc. Properties : Transparent Refractive Index : from 1,48 to 1,51 Axial angle 2V: 63°
A new study uses carbon isotope dating to determine the first precise age for this bed, and ties the western coast of Africa to 30 million years of global geologic records
Paleontologists at Southern Methodist University have measured the carbon isotopes in marine fossils to precisely date for the first time 30 million years of sediments along Africa’s South Atlantic shoreline.
The researchers matched the pattern of ratios of carbon-13 and carbon-12 isotopes in marine fossils from Africa’s South Atlantic shoreline to known patterns of carbon ratios in fossils found elsewhere in the world. From that they determined the age of the coastal sediments at a fossil locality near the southern Angolan village of Bentiaba, said paleontologist Christopher Strganac, lead author on the study.
The analysis focused on a sequence of shoreline sediments totaling 140 meters thick. Their age spans a timeline of nearly 30 million years, from 95 million years ago to 68 million years ago. That period was about 40 million years after Africa and South America split, allowing the South Atlantic Ocean to slowly emerge.
The analysis revealed that the richest marine reptile fossil bed on Africa’s South Atlantic dated to 71.5 million years ago, he said. This new date at the Bentiaba locality is more than 2 million years older than the estimated date of about 69 million years previously assigned to those marine beds by earlier researchers.
Africa’s South Atlantic coast is remarkable in plate tectonics as the place where part of the prehistoric supercontinent Gondwana split 130 million years ago into what we now call Africa and South America.
“The precise age for these rocks allows better understanding of the ancient life and environments at Bentiaba by placing them accurately within the history of the ancient South Atlantic,” said Strganac, a doctoral student in SMU’s Roy M. Huffington Department of Earth Sciences. “It’s a benchmark now from the Southern Hemisphere with which we can better understand ancient life at that time.”
The precise dating was made possible by new scientific dating techniques. The age of the rocks hadn’t previously been assessed because Africa’s South Atlantic shore — noted for its puzzle-like fit with South America — has few localities with well-exposed rocks of this age. Also, it has been essentially unexplored by scientific expeditions since the 1960s largely because war and unrest prevented exploration in the previous century.
The new measurements stem from the work of Projecto PaleoAngola, an international team of scientists who in recent years have explored Angola and discovered an abundance of fossils. Their discoveries include the bones of dinosaurs, whales, mosasaurs and other ancient life from what is the richest marine reptile fossil bed along the South Atlantic coast.
Strganac and his co-authors report their findings in the Journal of African Earth Sciences.
“This improvement in understanding the ages of the rocks along the shore is a great first step in trying to understand the climatic and evolutionary events that accompanied the growth of this ocean,” said vertebrate paleontologist Louis L. Jacobs, also a co-author on the study and co-leader of Projecto PaleoAngola. Jacobs describes Angola as “an untapped frontier” for fossil hunters.
Aids in new knowledge of climate, temperature and vegetation
Scientists have recognized since the 1960s that ancient supercontinents split apart and their remnants drifted to the current positions of today’s continents over the course of millions of years. One of the results was the creation of vast new oceans. Little is known of the vertebrate life that lived during that time along the eastern and western margins of the emerging South Atlantic Ocean.
Fossils being discovered now by Projecto PaleoAngola hold the key to understanding the South Atlantic Ocean’s ancient past. Analysis of the fossils sheds light on the paleoenvironment, including changes in climate, temperature, vegetation and ecology.
The geologic time period covered by the 30-million-year sequence represents the Late Cretaceous. Studies have shown it was a period of dramatic change in climate, beginning with one of the warmest periods on Earth, then starting to transition to cooler climates, Strganac said.
Determining carbon ratios allowed comparison with global geologic events
To discover the age of the sediments, Strganac tested 55 fossil shells of ancient oysters and clams from 40 different rock layers on the coast. Testing determined the ratio of stable carbon isotopes, carbon-13 and carbon-12, in each shell. Because these isotopes do not decay with time, the relative abundance of each relates to the ocean when the shells formed. These isotope ratios can be compiled as a sequence with the rock layers, producing a pattern of carbon isotope change in the ancient oceans through millions of years. To accurately date the rocks, Strganac matched the pattern in isotope ratios in the shell record at Angola with the pattern known from ancient geologic events that occurred elsewhere in the world.
Specifically, the red rift-valley layers at Bentiaba were deposited as Africa and South America began to split. Also observed in the layers are a reversal in Earth’s magnetic polarity at 71.4 million to 71.64 million years to delimit the age of marine fossils; rocks deposited in the South Atlantic Ocean 93.9 million years ago during an oceanic anoxic event; and rocks south of Bentiaba that bracket the mass extinction of dinosaurs at 66 million years.
Besides comparing the stable carbon isotopes, other measuring techniques included: magnetostratigraphy, which measures the ancient polarity of Earth’s magnetic field when various sedimentary layers were deposited; and argon-argon radiometric dating of a volcanic basalt layer at the site, which measures the radioactive decay of potassium to argon and dates the cooling of the volcanic lava to 85 million years ago.
“Adding a new ocean to the globe, in this case the South Atlantic, has many long-lasting effects,” said SMU’s Jacobs. “One obvious example is the formation of energy resources found along the coasts of Brazil and Angola.”
Note : The above story is based on materials provided by Southern Methodist University. The original article was written by Margaret Allen.
GPS measurements show that the Sierra Nevada and Coast Ranges rise several millimeters per year (red dots) as a result of groundwater pumping in the Central Valley (brown). Blue dots are sites where the ground has subsided. Credit: Image courtesy of UC Berkeley
Winter rains and summer groundwater pumping in California’s Central Valley make the Sierra Nevada and Coast Ranges sink and rise by a few millimeters each year, creating stress on the state’s earthquake faults that could increase the risk of a quake.
Gradual depletion of the Central Valley aquifer because of groundwater pumping also raises these mountain ranges by a similar amount each year — about the thickness of a dime — with a cumulative rise over the past 150 years of up to 15 centimeters (6 inches), according to calculations by a team of geophysicists.
While the seasonal changes in the Central Valley aquifer have not yet been firmly associated with any earthquakes, studies have shown that similar levels of periodic stress, such as that caused by the motions of the moon and sun, increase the number of microquakes on the San Andreas Fault, which runs parallel to the mountain ranges. If these subtle seasonal load changes are capable of influencing the occurrence of microquakes, it is possible that they can sometimes also trigger a larger event, said Roland Bürgmann, UC Berkeley professor of earth and planetary science at UC Berkeley.
“The stress is very small, much less than you need to build up stress on a fault toward an earthquake, but in some circumstances such small stress changes can be the straw that broke the camel’s back; it could just give that extra push to get a fault to fail,” Bürgmann said.
Bürgmann is a coauthor of a report published online this week by the journal Nature. The study, based on detailed global positioning satellite (GPS) measurements from California and Nevada between 2007 and 2010, was led by former UC Berkeley postdoctoral fellows Colin Amos, now at Western Washington University, and Pascal Audet, now of the University of Ottawa. The detailed GPS analysis was performed by William C. Hammond and Geoffrey Blewitt of the University of Nevada, Reno.
Draining of Central Valley
Water has been pumped from California’s Central Valley for more than 150 years, reducing what used to be a marsh and extensive lake, Tulare Lake, into fertile agricultural fields that feed the world. In that time, approximately 160 cubic kilometers (40 cubic miles) of water was removed — the capacity of Lake Tahoe — dropping the water table in some areas more than 120 meters (400 feet) and the ground surface 5 meters (16 feet) or more.
The weight of water removed allowed the underlying crust or lithosphere to rise by so-called isostatic rebound, which has raised the Sierra probably as much as half a foot since about 1860, Bürgmann said.
The same rebound happens as a result of the state’s seasonal rains. Torrential winter storms drop water and snow across the state, which eventually flow into Central Valley streams, reservoirs and underground aquifer, pushing down the crust and lowering the Sierra 1-3 millimeters. In the summer, water flow through the delta into the Pacific Ocean, evaporation and ground water pumping for irrigation, which has accelerated in the past few years because of a drought, allows the crust and surrounding mountains to rise again.
Bürgmann said that the flexing of Earth’s crust downward in winter would clamp the San Andreas Fault tighter, lowering the risk of quakes, while in summer the upward flexure would relieve this clamping and perhaps increase the risk.
“The hazard is ever so slightly higher in the summer than in the wintertime,” he said. “This suggests that climate and tectonics interact; that water changes ultimately affect the deeper Earth too.”
High-resolution mapping with continuous GPS
Millimeter-precision measurements of elevation have been possible only in the last few years, with improved continuous GPS networks — part of the National Science Foundation-funded Plate Boundary Observatory, which operates 1,100 stations around the western U.S. — and satellite-based interferometric synthetic aperture radar (InSAR). Synthetic aperture radar is a form of radar in which phase information is used to map elevation.
These measurements revealed a steady yearly rise of the Sierra of 1-2 millimeters per year, which was initially ascribed to tectonic activity deep underground, even though the rate was unusually high, Bürgmann said. The new study provides an alternative and more reasonable explanation for the rise of the Sierra in historic times.
“The Coast Range is doing the same thing as the Sierra Nevada, which is part of the evidence that this can’t be explained by tectonics,” he said. “Both ranges have uplifted over the last few years and they both exhibit the same seasonal up and down movement in phase. This tells us that something has to be driving the system at a seasonal and long-term sense, and that has to be groundwater recharging and depletion.”
In response to the current drought, about 30 cubic kilometers (7.5 cubic miles) of water were removed from Central Valley aquifers between 2003 and 2010, causing a rise of about 10 millimeters (2/5 inch) in the Sierra over that time.
After the new results were shared with colleagues, Bürgmann said, some geologists suggested that the state could get a better or at least comparable inventory of available water each year by using GPS to measure ground deformation instead of measuring snowpack and reservoir levels.
Other coauthors are Colin B. Amos of Western Washington University in Bellingham, Ingrid A. Johanson of UC Berkeley. Funding for the research came from NSF EarthScope and UC Berkeley’s Miller Institute.
Note : The above story is based on materials provided by University of California – Berkeley. The original article was written by Robert Sanders
Chemical Formula: Ba(Fe2+,Mn2+,Mg)2(Al,Fe3+)2(PO4)3(OH)3 Locality: Rapid Creek (Cross Cut Creek), Big Fish River, Yukon Territories, Canada. Name Origin: Named for Alan Kulan (1921-1977), prospector who found the first specimen.
Kulandite is a very rare barium phosphate mineral. It is one of the rare minerals that are making their way out of the Yukon Territory and into the mineral market.
History
Discovery date : 1976 Town of Origin : RAPID CREEK, BIG FISH RIVER/BLOW RIVER AREA, YUKON Country of Origin : CANADA
Optical properties
Optical and misc. Properties : Transparent to Translucent Refractive Index : from 1,70 to 1,72 Axial angle 2V: 32°
Physical Properties
Cleavage: {010} Good, {100} Good Color: Blue, Blue green, Green, Black green. Density: 3.91 Diaphaneity: Transparent to Translucent Hardness: 4 – Fluorite Luminescence: Non-fluorescent. Luster: Vitreous – Adamantine Streak: greenish white
The gigantic gorge system Noctis Labyrinthus and Valles Marineris were created exclusively through the erosive force of immense lava flows. (Image: google.com/mars)
An Italian astronomer in the 19th century first described them as ‘canali’ – on Mars’ equatorial region, a conspicuous net-like system of deep gorges known as the Noctis Labyrinthus is clearly visible. The gorge system, in turn, leads into another massive canyon, the Valles Marineris, which is 4,000 km long, 200 km wide and 7 km deep. Both of these together would span the US completely from east to west.
As these gorges, when observed from orbit, resemble terrestrial canyons formed by water, most researchers assumed that immense flows of water must have carved the Noctis Labyrinthus and the Valles Marineris into the surface of Mars. Another possibility was that tectonic activity had created the largest rift valley on a planet in our solar system.
Lava flows caused the gorges
These assumptions were far from the mark, says Giovanni Leone, a specialist in planetary volcanism in the research group of ETH professor Paul Tackley. Only lava flows would have had the force and mass required to carve these gigantic gorges into the surface of Mars. The study was recently published in the Journal of Volcanology and Geothermal Research.
In recent years, Leone has examined intensively the structure of these canyons and their outlets into the Ares Vallis and the Chryse Planitia, a massive plain on Mars’ low northern latitude. He examined thousands of high-resolution surface images taken by numerous Mars probes, including the latest from the Mars Reconnaissance Orbiter, and which are available on the image databases of the US Geological Survey.
No discernible evidence of erosion by water
His conclusion is unequivocal: “Everything that I observed on those images were structures of lava flows as we know them on Earth,” he emphasises. “The typical indicators of erosion by water were not visible on any of them.” Leone therefore does not completely rules out water as final formative force. Evidence of water, such as salt deposits in locations where water evaporated from the ground or signs of erosion on the alluvial fans of the landslides, are scarce but still existing. “One must therefore ask oneself seriously how Valles Marineris could have been created by water if one can not find any massive and widespread evidence of it.” The Italian volcanologist similarly could find no explanation as to where the massive amounts of water that would be required to form such canyons might have originated.
Source region of lava flows identified
The explanatory model presented by Leone in his study illustrates the formation history from the source to the outlet of the gorge system. He identifies the volcanic region of Tharsis as the source region of the lava flows and from there initial lava tubes stretched to the edge of the Noctis Labyrinthus. When the pressure from an eruption subsided, some of the tube ceilings collapsed, leading to the formation of a chain of almost circular holes, the ‘pit chains’.
When lava flowed again through the tubes, the ceilings collapsed entirely, forming deep V-shaped troughs. Due to the melting of ground and rim material, and through mechanical erosion, the mass of lava carved an ever-deeper and broader bed to form canyons. The destabilised rims then slipped and subsequent lava flows carried away the debris from the landslides or covered it. “The more lava that flowed, the wider the canyon became,” says Leone.
Leone supported his explanatory model with height measurements from various Mars probes. The valleys of the Noctis Labyrinthus manifest the typical V-shape of ‘young’ lava valleys where the tube ceilings have completely collapsed. The upper rims of these valleys, however, have the same height. If tectonic forces had been at work, they would not be on the same level, he says. The notion of water as the formative force, in turn, is undermined by the fact that it would have taken tens of millions of cubic kilometres of water to carve such deep gorges and canyons. Practically all the atmospheric water of all the ages of Mars should have been concentrated only on Labyrinthus Noctis. Moreover, the atmosphere on Mars is too thin and the temperatures too cold. Water that came to the surface wouldn’t stay liquid, he notes: “How could a river of sufficient force and size even form?”
Life less likely
Leone’s study could have far-reaching consequences. “If we suppose that lava formed the Noctis Labyrinthus and the Valles Marineris, then there has always been much less water on Mars than the research community has believed to date,” he says. Mars received very little rain in the past and it would not have been sufficient to erode such deep and large gorges. He adds that the shallow ocean north of the equator was probably much smaller than imagined – or hoped for; it would have existed only around the North Pole. The likelihood that life existed, or indeed still exists, on Mars is accordingly much lower.
Leone can imagine that the lava tubes still in existence are possible habitats for living organisms, as they would offer protection from the powerful UV rays that pummel the Martian surface. He therefore proposes a Mars mission to explore the lava tubes. He considers it feasible to send a rover through a hole in the ceiling of a tube and search for evidence of life. “Suitable locations could be determined using my data,” he says.
Swimming against the current
With his study, the Italian is swimming against the current and perhaps dismantling a dogma in the process. Most studies of the past 20 years have been concerned with the question of water on Mars and how it could have formed the canyons. Back in 1977, a researcher first posited the idea that the Valles Marineris may have been formed by lava, but the idea failed to gain traction. Leone says this was due to the tunnel vision that the red planet engenders and the prevailing mainstream research. The same story has been told for decades, with research targeted to that end, without achieving a breakthrough. Leone believes that in any case science would only benefit in considering other approaches. “I expect a spirited debate,” he says. “But my evidence is strong.”
Rrference:
Leone G. A network of lava tubes as the origin of Labyrinthus Noctis and Valles Marineris on Mars. Journal of Volcanology and Geothermal Research, 277 (2014), 1-8. Published online 1 Mai 2014. DOI: 10.1016/j.jvolgeores.2014.01.011
Note : The above story is based on materials provided by Eidgenössische Technische Hochschule Zürich
This is an artist’s impression of Bitesantennary Site 17 million years ago. The cave was in the middle of a vast biologically diverse rainforest in an area that is now part of the Riversleigh World Heritage Fossil Site in northwestern Queensland, Australia. Tiny ostracods lived in a pool of water in the cave that was continually enriched by the droppings of thousands of bats. Artwork by Dorothy Dunphy, from the book Riversleigh, By M.Archer, S.J.Hand and H.Godthelp, published in 1991 by Reed Books. Credit: Credit: Dorothy Dunphy.
Preserved giant sperm from tiny shrimps that lived at least 17 million years ago have been discovered at the Riversleigh World Heritage Fossil Site by a team including UNSW Australia researchers.
The giant sperm are thought to have been longer than the male’s entire body, but are tightly coiled up inside the sexual organs of the fossilised freshwater crustaceans, which are known as ostracods.
“These are the oldest fossilised sperm ever found in the geological record,” says Professor Mike Archer, of the UNSW School of Biological, Earth and Environmental Sciences, who has been excavating at Riversleigh for more than 35 years.
“The Riversleigh fossil deposits in remote northwestern Queensland have been the site of the discovery of many extraordinary prehistoric Australian animals, such as giant, toothed platypuses and flesh-eating kangaroos. So we have become used to delightfully unexpected surprises in what turns up there.
“But the discovery of fossil sperm, complete with sperm nuclei, was totally unexpected. It now makes us wonder what other types of extraordinary preservation await discovery in these deposits.”
The study is published in the journal Proceedings of the Royal Society B.
A UNSW research team led by Professor Archer, Associate Professor Suzanne Hand and Henk Godthelp collected the fossil ostracods from Bitesantennary Site at Riversleigh in 1988.
They were sent to John Neil, a specialist ostracod researcher at La Trobe University, who realised they contained fossilised soft tissues.
He drew this to the attention of European specialists, including the lead author on the paper, Dr Renate Matzke-Karasz, from Ludwig Maximilian University of Munich, Germany, who examined the specimens with Dr Paul Tafforeau at the European Synchrotron Radiation Facility in Grenoble, France.
The microscopic study revealed the fossils contain the preserved internal organs of the ostracods, including their sexual organs. Within these are the almost perfectly preserved giant sperm cells, and within them, the nuclei that once contained the animals’ chromosomes and DNA.
Also preserved are the Zenker organs – chitinous-muscular pumps used to transfer the giant sperm to the female. The researchers estimate the fossil sperm are about 1.3 millimetres long, about the same length or slightly longer than the ostracod itself.
“About 17 million years ago, Bitesantennary Site was a cave in the middle of a vast biologically diverse rainforest. Tiny ostracods thrived in a pool of water in the cave that was continually enriched by the droppings of thousands of bats,” says Professor Archer.
UNSW’s Associate Professor Suzanne Hand, who is a specialist in extinct bats and their ecological role in Riversleigh’s ancient environments, says the bats could have played a role in the extraordinary preservation of the ostracod sperm cells.
The steady rain of poo from thousands of bats in the cave would have led to high levels of phosphorous in the water, which could have aided mineralisation of the soft tissues.
“This amazing discovery at Riversleigh is echoed by a few examples of soft-tissue preservation in fossil bat-rich deposits in France. So the key to eternal preservation of soft tissues may indeed be some magic ingredient in bat droppings,” says Associate Professor Hand.
Previous discoveries of extraordinary preservation at Riversleigh include insects with internal muscles that have been preserved because bacteria became fossilised as they attempted to consume the soft tissues of these creatures.
Perfectly preserved cells of leaves have been found, as well as the preserved soft tissue of eyeballs in the eye sockets of some of the extinct marsupials.
Note : The above story is based on materials provided by University of New South Wales
Chemical Formula: Na2Cu(SO4)2·2H2O Locality: Chuquicamata, Calama, Antofagásta Province, Chile. Name Origin: Named after B. Kroehnke, who was the first person to analyze it.
Kröhnkite ( Na2Cu(SO4)2·2H2O ) is a rare copper sulfate mineral named after B. Kröhnke who first researched it.
Discovery and occurrence
Kröhnkite was first researched after an occurrence in the Chuquicamata Mine, Chile, and has been reported from a number of locations in the Atacama region. Associated minerals in the discovery location include; atacamite, blodite, chalcanthite, antlerite and natrochalcite. It occurs in the oxidized zone of copper deposits in arid environments.
History
Discovery date : 1876 Town of Origin : CHUQUICAMATA, ANTOFAGASTA Country of Origin: CHILE
Physical Properties
Cleavage: {010} Perfect, {011} Good Color: Blue, Dark sky blue, Greenish blue, Yellowish green. Density: 2.06 – 2.9, Average = 2.48 Diaphaneity: Transparent to Translucent Fracture: Conchoidal – Fractures developed in brittle materials characterized by smoothly curving surfaces, (e.g. quartz). Hardness: 2.5-3 – Finger Nail-Calcite Luster: Vitreous (Glassy) Streak: white
This image shows a reconstruction of Plexus ricei. Credit: Droser Lab, UC Riverside.
RIVERSIDE, Calif. — Scientists at the University of California, Riverside have discovered a fossil of a newly discovered organism from the “Ediacara Biota” — a group of organisms that occurred in the Ediacaran period of geologic time.
Named Plexus ricei and resembling a curving tube, the organism resided on the Ediacaran seafloor. Plexus ricei individuals ranged in size from 5 to 80 centimeters long and 5 to 20 millimeters wide. Along with the rest of the Ediacara Biota, it evolved around 575 million years ago and disappeared from the fossil record around 540 million years ago, just around the time the Cambrian Explosion of evolutionary history was getting under way.
“Plexus was unlike any other fossil that we know from the Precambrian,” said Mary L. Droser, a professor of paleontology, whose lab led the research. “It was bilaterally symmetrical at a time when bilaterians—all animals other than corals and sponges—were just appearing on this planet. It appears to have been very long and flat, much like a tapeworm or modern flatworm.”
Study results appeared online last month in the Journal of Paleontology.
“Ediacaran fossils are extremely perplexing: they don’t look like any animal that is alive today, and their interrelationships are very poorly understood,” said Lucas V. Joel, a former graduate student at UC Riverside and the first author of the research paper. Joel worked in Droser’s lab until June 2013.
He explained that during the Ediacaran there was no life on land. All life that we know about for the period was still in the oceans.
“Further, there was a complete lack of any bioturbation in the oceans at that time, meaning there were few marine organisms churning up marine sediments while looking for food,” he said. “Then, starting in the Cambrian period, organisms began churning up and mixing the sediment.”
According to the researchers, the lack of bioturbators during the Ediacaran allowed thick films of (probably) photosynthetic algal mats to accumulate on ocean floors—a very rare environment in the oceans today. Such an environment paved the way for many mat-related lifestyles to evolve, which become virtually absent in the post-Ediacaran world.
“The lack of bioturbation also created a very unique fossil preservational regime,” Joel said. “When an organism died and was buried, it formed a mold of its body in the overlying sediment. As the organism decayed, sediment from beneath moved in to form a cast of the mold the organism had made in the sediment above. What this means is that the fossils we see in the field are not the exact fossils of the original organism, but instead molds and casts of its body.”
Paleontologists have reported that much of the Ediacara Biota was comprised of tubular organisms. The question that Droser and Joel addressed was: Is Plexus ricei a tubular organism or is it an organism that wormed its way through the sand, leaving a trail behind it?
“In the Ediacaran we really need to know the difference between the fossils of actual tubular organisms and trace fossils because if the fossil we are looking at is a trace fossil, then that has huge implications for the earliest origins of bilaterian animals—organisms with bilateral symmetry up and down their midlines and that can move independently of environment forces,” Joel said. “Being able to tell the difference between a tubular organism and a trace fossil has implications for the earliest origins of bilaterian organism, which are the only kinds of creatures that could have constructed a tubular trace fossil. Plexus is not a trace fossil. What our research shows is that the structure we see looks very much like a trace fossil, but is in fact a new Ediacaran tubular organism, Plexus ricei.”
Plexus ricei was so named for plexus, meaning braided in Latin, a reference to the organism’s morphology, and ricei for Rice, the last name of the South Australian Museum’s Dennis Rice, one of the field assistants who helped excavate numerous specimens of the fossil.
“At this time, we don’t know for sure that Plexus ricei was a bilateral but it is likely that it was related to our ancestors,” Droser said.
Note : The above story is based on materials provided by University of California – Riverside
Most supposed impact indicators at 29 sites are too old or too young to be remnants of an ancient comet that proponents claim sparked climate change at the end of the Ice Age, killed America’s earliest people and caused a mass animal extinction.
Controversy over what sparked the Younger Dryas, a brief return to near glacial conditions at the end of the Ice Age, includes a theory that it was caused by a comet hitting Earth.
As proof, proponents point to sediments containing deposits they believe could result only from a cosmic impact.
Now a new study disproves that theory, said archaeologist David Meltzer, Southern Methodist University, Dallas. Meltzer is lead author on the study and an expert in the Clovis culture, the peoples who lived in North America at the end of the Ice Age.
Meltzer’s research team found that nearly all sediment layers purported to be from the Ice Age at 29 sites in North America and on three other continents are actually either much younger or much older.
Scientists agree that the brief episode at the end of the Ice Age — officially known as the Younger Dryas for a flower that flourished at that time — sparked widespread cooling of Earth 12,800 years ago and that this cool period lasted for 1,000 years. But theories about the cause of this abrupt climate change are numerous. They range from changes in ocean circulation patterns caused by glacial meltwater entering the ocean to the cosmic-impact theory.
The cosmic-impact theory is said to be supported by the presence of geological indicators that are extraterrestrial in origin. However a review of the dating of the sediments at the 29 sites reported to have such indicators proves the cosmic-impact theory false, said Meltzer.
Meltzer and his co-authors found that only three of 29 sites commonly referenced to support the cosmic-impact theory actually date to the window of time for the Ice Age.
The findings, “Chronological evidence fails to support claim of an isochronous widespread layer of cosmic impact indicators dated to 12,800 years ago,” were reported May 12, 2014, in the Proceedings of the National Academy of Sciences.
Co-authors were Vance T. Holliday and D. Shane Miller, both from the University of Arizona; and Michael D. Cannon, SWCA Environmental Consultants Inc., Salt Lake City, Utah.
“The supposed impact markers are undated or significantly older or younger than 12,800 years ago,” report the authors. “Either there were many more impacts than supposed, including one as recently as 5 centuries ago, or, far more likely, these are not extraterrestrial impact markers.”
Dating of purported Younger Dryas sites proves unreliable
The Younger Dryas Impact Hypothesis rests heavily on the claim that there is a Younger Dryas boundary layer at 29 sites in the Americas and elsewhere that contains deposits of supposed extraterrestrial origin that date to a 300-year span centered on 12,800 years ago.
The deposits include magnetic grains with iridium, magnetic microspherules, charcoal, soot, carbon spherules, glass-like carbon containing nanodiamonds, and fullerenes with extraterrestrial helium, all said to result from a comet or other cosmic event hitting Earth.
Meltzer and his colleagues tested that hypothesis by investigating the existing stratigraphic and chronological data sets reported in the published scientific literature and accepted as proof by cosmic-impact proponents, to determine if these markers dated to the onset of the Younger Dryas.
They sorted the 29 sites by the availability of radiometric or numeric ages and then the type of age control, if available, and whether the age control is secure.
The researchers found that three sites lack absolute age control: at Chobot, Alberta, the three Clovis points found lack stratigraphic context, and the majority of other diagnostic artifacts are younger than Clovis by thousands of years; at Morley, Alberta, ridges are assumed without evidence to be chronologically correlated with Ice Age hills 2,600 kilometers away; and at Paw Paw Cove, Maryland, horizontal integrity of the Clovis artifacts found is compromised, according to that site’s principal archaeologist.
The remaining 26 sites have radiometric or other potential numeric ages, but only three date to the Younger Dryas boundary layer.
At eight of those sites, the ages are unrelated to the supposed Younger Dryas boundary layer, as for example at Gainey, Michigan, where extensive stratigraphic mixing of artifacts found at the site makes it impossible to know their position to the supposed Younger Dryas boundary layer. Where direct dating did occur, it’s sometime after the 16th century A.D.
At Wally’s Beach, Alberta, a radiocarbon age of 10,980 purportedly dates extraterrestrial impact markers from sediment in the skull of an extinct horse. In actuality, the date is from an extinct musk ox, and the fossil yielding the supposed impact markers was not dated, nor is there evidence to suggest that the fossils from Wally’s Beach are all of the same age or date to the Younger Dryas onset.
At nearly a dozen other sites, the authors report, the chronological results are neither reliable nor valid as a result of significant statistical flaws in the analysis, the omission of ages from the models, and the disregard of statistical uncertainty that accompanies all radiometric dates.
For example, Lake Cuitzeo, Mexico, Meltzer and his team used the data of previous researchers and applied a fifth-order polynomial regression, but it returned a different equation that put the cosmic-impact markers at a depth well above that which would mark the Younger Dryas onset.
The authors go on to point out that inferences about the ages of supposed Younger Dryas boundary layers are unsupported by replication in more cases than not.
In North America, the Ice Age was marked by the mass extinction of several dozen genera of large mammals, including mammoths, mastodons, American horses, Western camels, two types of deer, ancient bison, giant beaver, giant bears, sabre-toothed cats, giant bears, American cheetahs, and many other animals, as well as plants.
Note : The above story is based on materials provided by Southern Methodist University.
