WFS

Formation of sedimentary layers of white clay, Tamilnadu, India

Fossil site for wood fossils, Tamilnadu, India

Fossil site in Kerala, India

Fossil wood park maintained by geological survey of India at Tamilnadu

Cretaceous fossil sites india

Fossils in rack:-Cyad

Fossils in rack:-echiniderms

Fossils in rack:-Rastellum sp

Pre-historic seabed, Cretaceous period

Spinosaurus Devoured Meals Like a Giant Pelican

January 19th, 2016

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Spinosaurus gained a notorious reputation in Jurassic Park 3 (spoiler alert), stomping on to the screen to take down the mighty T. rex in a rather memorable duel. Since gaining global fame on the silver screen, researchers now believe Spinosaurus was an adept swimmer, terrorizing local inhabitants of ancient river systems in North Africa some 100 million years ago.

Spinosaurus may have eaten its prey much like a giant pelican or modern day snakes. (Credit: Sergey Krasovskiy)

A new study of the jaws of Spinosaurus indicates that it may have devoured its prey much like a giant pelican or modern snakes, opening its jaws wide to swallow unlucky critters whole. New fossils from rocks dating to the Cretaceous period from southeastern Morocco, known as the Kem-Kem beds, show that spinosaurs were able to widen their jaws and greatly open the pharynx to swallow over-sized chunks of food.

Part Crocodile, Part Pelican

“Spinosaurs were very strange animals with a crocodile-like skull showing a long and narrow snout and conical teeth,” says Octávio Mateus from Universidade Nova de Lisboa, Portugal. This has usually led to interpretations of spinosaurs as skilled fish hunters that may have even used their long claws as fish hooks.

The new study, published recently in the open-access journal PLOS One, is the first time a pelican-like feeding style has been discovered in dinosaurs. Christophe Hendrickx, lead author of the study and also at the Universidade Nova de Lisboa, noted that an unusual aspect of spinosaur jaws led to this conclusion.

An illustration of Spinosaurus swallowing a snack. (Credit: Jason Poole)

“The mandibular symphysis [where the jaw bones meet at the front] of spinosaurids shows prominent parallel ridges where connective tissues got attached,” Henrickx says. This was combined with spinosaurs’ highly unusual anatomy where the lower jawbones articulated with the skull, which were much more free and mobile than other theropod dinosaurs.

The design of the spinosaur jaw enabled the left and right jaws to be more movable and widen much more than if they were fused together like other bones in the skull. Similar feeding mechanics have also been suggested in pterosaurs, the cousins of dinosaurs, which are thought to also have preyed largely on fish.

Why spinosaurs adapted to dine like this is still up for debate. Hendrickx suggests that being able to eat large prey rapidly was necessary to sustain an animal of such a massive size. Spinosaurus grew up to 50 feet in length – longer than a T. rex. Gulping down food in a single bite might have also given them a competitive edge in a time when herbivorous dinosaurs, usually the prey of choice for theropod predators, in North Africa were relatively rare.Although often imagined as an adept fisher, Spinosaurus and its large relatives might also have preyed on other animals careless enough to get too close.

Christophe Hendrickx stands before a Spinosaurus skull.

“It is very possible that the two spinosaurs from Morocco were also eating other type of preys such as herbivorous dinosaurs, pterosaurs, crocodiles, and turtles, and probably swallowed them as a whole if these preys were not too large,” Hendrickx says.

The newly discovered remains also help confirm a previous suspicion that the fossilized remains used to reconstruct Spinosaurus probably came from at least two different closely related species. Serjoscha Evers, a researcher at the University of Oxford who works on North African spinosaurs but was not involved in the present study, thinks the “environment of a near-coast river system would have supported their high diversity,” and that predators like spinosaurs were extreme specialists, “with niche partitioning playing a major role.”

Either way, the vision of a 15-meter-long crocodile-like dinosaur gulping its prey down is pretty terrifying.

Courtesy:Article By Jon Tennant,Discover Magazine.

Key: WFS,Riffin T Sajeev,Russel T Sajeev,World Fossil Society

Glossopteris Impressions from Karai Formation

January 17th, 2016

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Glossopteris Fossil leaf Impressions on clay.Karai Formation. Specimen collected Athira .(C) World Fossil Society.

Glossopteris Fossil leaf Impressions on clay.Karai Formation. Specimen collected By Athira .(C) World Fossil Society.

The Glossopteridales are an extinct group of seed plants that arose during the Permian on the great southern continent of Gondwana. These plants went on to become a dominant part of the southern flora through the rest of the Permian, though they dwindled to extinction by the end of the Triassic Period.

Glossopteris, the genus from which the group gets its name, is also the largest and best-known member of the Glossopteridales. More than 70 species of this genus have been recognized in India alone, with additional species from South America, Australia, Africa, and Antarctica. Only a few fossils from the northern hemisphere have been considered as members of this group, but these are not identified with great certainty.

Fossils of the gymnosperm Glossopteris (dark green) found in all of the southern continents provide strong evidence that the continents were once amalgamated into a supercontinent Gondwana

The rapid appearance, expansion, and relatively quick extinction of this group, as well as the large number of species, has made the group very important for understanding paleobiogeography, specifically in the recognition of areas that were once connected together, but are now separated through the action of continental drift. As a result, there is a wealth of descriptive literature available on glossopterids. However, most of the available fossils are sterile leaves lying unattached to stems, and so a number of species which have been described are not well differentiated, and few are known from distinctive reproductive structures. This makes it difficult to be certain of the actual number of species.

The large number of leaves found preserved, and the character of the deposits in which these are found, suggest that glossopterids were deciduous, losing their leaves in the autumn, and growing new leaves in each spring. Some specimens show an abscission zone, such as that along which a leaf detaches in living plants. A number of tiny scale-leaves have also been found; these may represent first-growth leaves or bud scales. Mature leaves were often 10 cm long, and some leaves have been found over a meter in length. These mature leaves are very easy to recognize, since they have a strong central vein and a network of smaller veins. This is quite different from the other seed plants of the Late Paleozoic and early Mesozoic, which usually had no midvein and secondary veins which ran parallel to each other. You can see the striking preservation of these vein networks in the picture below.

The reproductive structures of glossopterids are as unusual as the foliage leaves. They appear to have been borne on leaves as in other “pteridosperms“. Poor preservation has led to much controversy over their structure and their arrangement on living plants from which they came. At least one point has become clear: pollen and seeds were produced in different organs, attached to separate leaves, though the specifics of the organs themselves are not as clearly settled. Pollen organs have been described as anything from a modified leaf bearing stalked pollen sacs to cone-like clusters.

Glossopteris Fossil leaf Impressions on clay.Karai Formation. Specimen collected By Athira . (C) World Fossil Society.

More common as fossils than pollen organs are ovule-bearing organs (those that are responsible for producing seeds). A dazzling variety of these structures has been found, suggesting that this really was a large and diverse group of plants. Seeds appear to have been produced on the underside of the leaf, with the leaf edges rolled over to form an enclosing chamber. This may not have been the case for all species, since at least some fossils have been reconstructed with ovules hanging in clusters from a much smaller, and un-enclosing leaf.

In addition to their distinctive foliage and reproductive structures, glossopterids also have unusual roots. These have been asigned to the form genus Vertebraria, so called because of the regularly spaced partitions which give the appearance of a backbone. The roots are remarkable for the lobed wood at their center, with internal spaces between the lobes — a highly unusual morphology among plants.

Courtesy: Article UCMP Berkely and Taylor, T. N. & E. L. Taylor. 1993. The Biology and Evolution of Fossil Plants, Prentice Hall, NJ, USA.

Key: WFS,Riffin T Sajeev,Russel T Sajeev,World Fossil Society,Karai Formation

A ‘kink’ in fault explains long-term growth of the Himalaya

January 16th, 2016

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An international team of scientists has shed new light on the earthquake that devastated Nepal in April 2015, killing more than 8,000 people.

A study published in the journal Nature Geoscience shows that a kink in the regional fault line below Nepal explains why the highest mountains in the Himalayas are seen to grow between earthquakes. This kink has created a ramp 20km below the surface, with material constantly being pushed up and raising the height of the mountains.

Himalaya Mountains.Credit: © THPStock / Fotolia

The researchers, from the UK’s Centre for the Observation and Modelling of Earthquakes, Volcanoes and Tectonics (COMET), as well as academics from the USA and France, also demonstrate that the rupture on the fault stopped 11km below Kathmandu. This indicates that another major earthquake could take place within a shorter timeframe than the centuries that might be expected for the area.

Lead author Dr John Elliott of Oxford University, a member of the COMET team, said: ‘Nepal has some of the highest mountain ranges in the world that have been built up over millions of years because of the collision of India with Asia. But the way in which mountains grow and when this occurs is still debated.

‘We have shown that the fault beneath Nepal has a kink in it, creating a ramp 20km underground. Material is continually being pushed up this ramp, which explains why the mountains were seen to be growing in the decades before the earthquake.

‘The earthquake itself then reversed this, dropping the mountains back down again when the pressure was released as the crust suddenly snapped in April 2015.

‘Using the latest satellite technology, we have been able to precisely measure the land height changes across the entire eastern half of Nepal. The highest peaks dropped by up to 60cm in the first seconds of the earthquake.’

Mount Everest, at more than 50km east of the earthquake zone, was too far away to be affected by the subsidence seen in this event.

Dr Pablo Gonzalez of the University of Leeds, a member of the COMET team, said: ‘We successfully mapped the earthquake motion using satellite technology on a very difficult mountainous terrain. We developed newly processing algorithms to obtain clearer displacement maps, which revealed the most likely fault geometry at depth. Such geometry makes sense of the puzzling geological observations.’

Another key finding of the study shows that the rupture in the fault stopped 11km below Kathmandu, leaving an upper portion that remains unbroken.

Dr Elliott said: ‘Using the high-resolution satellite images, we have shown that only a small amount of the earthquake reached the surface. This is surprising for such a big earthquake, which we would normally expect to leave a major fault trace in the landscape. This makes it a challenge when trying to find past earthquake ruptures, as they could be hidden.

‘We found that the rupture from April’s earthquake stopped 11km beneath Kathmandu, and that this sudden break is because of damage to the fault from interactions with older faults in the region. This is important because the upper half of the fault has not yet ruptured, but is continuously building up more pressure over time as India continues to collide into Nepal.

‘As this part of the fault is nearer the surface, the future rupture of this upper portion has the potential for a much greater impact on Kathmandu if it were to break in one go in a similar sized event to that of April 2015.

‘Work on other earthquakes has suggested that when a rupture stops like this, it can be years or decades before it resumes, rather than the centuries that might usually be expected.

‘Unfortunately, there is no way of predicting precisely when another earthquake will take place. It’s simply a case of countries and cities making sure they are well prepared for when it does happen.’

The research was a collaboration between scientists from the University of Oxford, the University of Leeds, the University of Cambridge, California Institute of Technology, PSL Research University (France), and engineering consultancy Arup.

The majority of the work was funded by the Natural Environment Research Council (NERC).

Citation: University of Oxford. “Scientists pinpoint unbroken section of Nepal fault line and show why Himalayas grow.” ScienceDaily. ScienceDaily, 11 January 2016. <www.sciencedaily.com/releases/2016/01/160111135046.htm

Key.WFS,Riffin T Sajeev,Russel T Sajeev,World Fossil Society

Sivatherium: Largest Giraffe

January 15th, 2016

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A prehistoric giraffe that died out 10,000 years ago might have been the largest ruminant that walked the Earth.Victorian scientists believed the creature was a giraffe with a trunk and a “missing link” between mammals.Digital reconstructions of the bones show that while the giraffe was gigantic, the theory that it was as big as an elephant was not true.The findings, published in Biology Letters, shed new light on the work of 19th Century fossil hunters.

The large relative of the giraffe lived one million years ago

The first fossil specimen was found by the Scottish geologist Hugh Falconer and the English engineer Proby Thomas Cautley on an expedition to the Siwalik hills in India in the 1830s.In a paper published in 1836, the two men outlined their discovery of an animal with a skull the size of an elephant which they believed had a trunk.

Palaeontologists envisaged it as an elephant sized, moose-like creature – a view that has prevailed.

Christopher Basu of the Royal Veterinary College in Hertfordshire, co-researcher of the study, said the fossil hunters did a “beautiful job at describing it and taking measurements”, although it turns out the body mass calculation was “educated guesswork”.

Basu C et al/Biology Letters Image caption Sivatherium giganteum reconstructed in 3D

Basu C et al/Biology Letters: Sivatherium giganteum reconstructed in 3D

Sivatherium was a giant relative of modern giraffes, living over one million years ago in both Africa and Asia.Unlike the giraffes of today, Sivatherium had a short neck, with short, stocky legs.At the time of the first discovery of bones of the mammal in the 1800s it was thought to be a link between giraffes and elephants.

“They thought it was this missing link animal,” Mr Basu, a veterinary scientist, told BBC News. “They had never seen anything that size with that kind of anatomy.”

As part of research into the anatomy of living giraffes, he used modern computer methods to investigate the skeleton of the giraffe “cousin”.

Largest ruminant

By reconstructing the animal’s anatomy in 3D, he was able to estimate its body mass.

“As a palaeontologist, it is really important to understand the basic question – how big was this animal?” he explained.

The research – carried out with Liverpool John Moores University – came up with an estimated body mass of 1,246kg (857 to 1,812kg range).This is thought to be an underestimate, as it does not take into account large horns possessed by the males.

Although its size does not approach that of an African elephant, the animal – dubbed “Siva’s beast” – was certainly a large member of the giraffe family and may have been the largest ruminant mammal that has ever lived.

“This was probably the largest giraffe relative to have ever existed, which makes it the largest ruminant that’s ever existed,” said Mr Basu, who is studying for a PhD.

Such a large ruminant might have struggled to eat enough to provide the energy needed to power such a large body, he added.

“It’s a rare animal,” he said. “It’s pushing the limits of its anatomy.”

Ref: Article by By Helen Briggs,BBC News

Key:WFS,Riffin T Sajeev,Russel T Sajeev,World Fossil Society,Sivatherium

Machimosaurus: Giant crocodile fossil

January 12th, 2016

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The biggest sea-dwelling crocodile ever found has turned up in the Tunisian desert. The whopper of a prehistoric predator grew to over 30 feet long (nearly ten meters) and weighed three tons.Paleontologists have dubbed the new species Machimosaurus rex and describe it Monday in the journal Cretaceous Research.Although the recovered remains are fragmentary, enough remained in the 120-million-year-old rock to identify the reptile as the largest known member of a peculiar lineage of crocodiles that spent their lives almost entirely at sea.

Machimosaurus could have grown to more than 30 feet (almost ten meters) long.ILLUSTRATION BY DAVIDE BONADONNA

“This is a neat new discovery from a part of the world that hasn’t been well-explored for fossils,” says University of Edinburgh paleontologist Stephen Brusatte, who was not involved with the new study.

The fossils, including a skull and a smattering of other bones, were discovered by Federico Fanti of the University of Bologna in Italy and colleagues with support from the National Geographic Society.

Big Bite : Scientists are awaiting the discovery of a more complete skeleton to figure out exactly how large Machimosaurus rex was. But assuming that the new species had similar proportions as its close relatives, Fanti estimates that Machimosaurus rex stretched about 31 feet (9.6 meters) in length.While not as large as some of its later, distant relatives that lived in freshwater, that makes Machimosaurus rex the biggest ocean-dwelling member of the crocodile family tree.

The biggest freshwater croc ever, Sarcosuchus imperator, lived 110 million years ago, grew as long as 40 feet (12 meters), and weighed up to eight metric tons (17,500 pounds). Since the time of this and other giants such as the alligator Deinosuchus, many crocodile lineages have died out, leaving today’s saltwater crocs closely related.The carnivore’s teeth may hint at what it fed on in the ancient ocean. “Machimosaurus rex had stocky, relatively short and rounded teeth,” Fanti says, “and a massive skull capable of a remarkable bite force.” This cluster of features leads Fanti to suggest that the croc was a generalist hunter that took a variety of prey, including large marine turtles.

“It would likely have been something of an ambush predator, hanging around in shallow water hunting turtles and fishes and maybe waiting for some land animals to come a little too close to the shore,” Brusatte adds.

Tough Survivor :For scientists, the most important aspect of Machimosaurus rex isn’t so much its size as when it lived.Paleontologists have long debated whether or not there was a mass extinction at the end of the Jurassic period, 145 million years ago. The group that includes Machimosaurus, called the teleosaurids, is among those thought to have died out.

A reconstruction of Machimosaurus rex based on the fossil bones found (white) shows its size compared with a human.
ARTWORK BY MARCO AUDITORE

The discovery of Machimosaurus rex in later rocks from the Cretaceous hints that if there was a mass extinction, it didn’t kill off life planetwide. “The new find adds to growing evidence that a lot of marine reptiles made it across the boundary and through the supposed extinction,” Brusatte says.

Rather than being a rapid extermination, the extinction may have been a more drawn-out transition. “In our interpretation,” Fanti says, “the end-Jurassic event was global in its effects but was mostly likely a complex sequence of local biological crises that are still poorly documented.”

One of the outstanding mysteries is why the marine crocodiles didn’t reclaim their former glory. Even though the family of Machimosaurus rex survived for longer than thought, they didn’t appear to thrive as they had in the Jurassic.

While Machimosaurus rex was certainly impressive in size, Brusatte says, “it may have just been a dead croc walking.”

Courtesy: Brian Switek’s blog Laelaps on NationalGeographic.com

Key: WFS,Riffin T Sajeev,Russel T Sajeev,World Fossil Society,Machimosaurus

Ontocetus oxymycterus: white whale fossil

January 9th, 2016

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A 15 million year-old fossil sperm whale specimen from California belongs to a new genus, according to a study published December 9, 2015 in the open-access journal PLOS ONE by Alexandra Boersma and Nicholas Pyenson from the Smithsonian’s National Museum of Natural History.

In this reconstruction, a pod of Albicetus travel together through the Miocene Pacific Ocean, surfacing occasionally to breathe. Modern sperm whales are also known for forming these tight-knit groups, composed mainly of females and their calves. Art by A. Boersma for the Smithsonian.Credit: A. Boersma; CCAL

The authors of the study reanalyzed the large but incomplete Ontocetus oxymycterus fossil sperm whale specimen from the middle Miocene Monterey Formation of California, originally described in 1925 by Remington Kellogg. Kellogg put this species in the genus Ontocetus, that was originally thought to be a tooth taxon; however, it is now known that in this genus, species have walrus tusks instead of a cetacean teeth. Thus, the authors assigned this species to the new genus Albicetus, creating the new combination of Albicetus oxymycterus, gen. nov. The authors used the term “Albicetus,” or “white whale,” because they were inspired by the fossil’s bone-white color, in homage to Melville’s famous fictitious leviathan Moby Dick.

The authors also analyzed whale’s body size in comparison to the sperm whale evolutionary tree. Kellogg originally placed this species in the genusOntocetus, an enigmatic tooth taxon reported from the 19th century. However, whales of large body size likely arose multiple times in the evolution of sperm whales, and the majority of these large whales also had unusually large upper and lower teeth. The authors suspect that the presence of big teeth in fossil sperm whales may suggest that they were feeding on large prey, perhaps marine mammals such as seals and other smaller whales as opposed to modern sperm whales, which feed primarily on squid, hardly using their teeth for chewing.

“This find means that, around 15 million years ago when there were a lot of large sperm whales with big teeth like Albicetus, it may have been a moment of peak richness in the number and diversity of marine mammals serving as prey to these whales,” Boersma suggests.

Source: PLOS. “Scientists discover ‘white whale’ fossil: Researchers re-analyze 15-million-year-old sperm whale fossil, find ‘white whale’.” ScienceDaily. ScienceDaily, 9 December 2015. <www.sciencedaily.com/releases/2015/12/151209183454

Key: WFS,Riffin T Sajeev,Russel T Sajeev,World Fossil Society,Whale fossil

The Subway Garnet

January 8th, 2016

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The American Museum of Natural History is a lot of things to a lot of people. To the wealthy philanthropist, it’s a venue for black-tie galas in the shadow of a 94-foot blue whale. To the young, it’s the setting for a movie franchise starring Ben Stiller that single-handedly made the educational diorama relevant again.

And then there are the scientists who avail themselves of the 33 million artifacts and specimens on exhibition and in storage at the museum, like a mastodon jaw.

Only 2 percent of the collection is on view, so any visiting geologist who wants to see what may be the museum’s most magnificent mineral must make an appointment with the Department of Earth and Planetary Sciences. That is the current repository of the once famed, now forgotten “Subway Garnet” — although that name is only half correct.

The Subway Garnet is currently in storage at the American Museum of Natural History. Credit Fred R. Conrad for The New York Times

The almandine garnet is as rare as it is large. A nine-pound bundle of iron and aluminum nearly six inches in diameter, the gem resembles nothing so much as Fred Flintstone’s bowling ball. It was discovered on 35th Street, between Seventh Avenue and Broadway — or rather eight feet under the street, during a sewer excavation in August 1885. It is estimated to be 430 million years old, and its nickname was bestowed by journalists who no doubt thought a subway dig would be a more genteel provenance than a sewer trench. (The garnet was unearthed years before Manhattan’s underground train tunnels would be dug.

“It’s rare in the sense of the size and perfection of it,” said George Harlow, the curator for the earth sciences department at the museum. “They’re usually all broken up at that size.”

The jaw of a mastodon, also part of the museum’s collection but not on display to the public. Credit Fred R. Conrad for The New York Times

Indeed, Columbia University is in possession of a once enormous almandine garnet that was discovered in the Adirondacks, near Gore Mountain. But the easily breakable block has since greatly diminished, thanks to decades of psychology students who broke off keepsake pieces when they defended their theses. When the Subway Garnet was discovered, it became the darling of contemporary scientific journals, but its origin story seems more suited to the gossip columns of the day. William Niven, the owner of a business that sold gemstones and minerals, claimed he picked up the garnet as he was passing by the site, just after an unnamed laborer dumped it on the street during the excavation. Dr. Niven then promptly sold it to one George F. Kunz (whom Professor Harlow describes as “the P.T. Barnum of mineralogists”) for $100. But as early as 1908, there are accounts of Kunz stating that he himself had found the garnet.

From there the gem made its way to the New York Mineralogical Club and then, in 1968, to the American Museum of Natural History, where it was proudly displayed in a case at the entrance to Mineral Hall until its relegation to a drawer on the fourth floor.

As for whether this remarkable link to our Paleozoic past might be excavated from storage, there is hope. “Nothing’s been finalized, but I believe plans are afoot,” said Professor Harlow, who has worked at the museum for 40 years. “I’d certainly like to see it available to the public before I retire.”

Courtesy: Article By BILL SCHULZ,nytimes.com

Key: WFS,Riffin T Sajeev,Russel T Sajeev,World Fossil Society,Garnet

Toxic Panthalassa May Have Triggered end-Triassic Mass Extinction

January 6th, 2016

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A mass extinction some 201 million years ago may have been triggered by changes in the biochemical balance of Panthalassa (also known as the Panthalassic Ocean) – the larger of the two oceans surrounding the supercontinent of Pangaea, according to a team of scientists led by Prof Jessica Whiteside from the University of Southampton, UK.

Prof Whiteside and her colleagues from the United States, Australia, and Canada, have found strong evidence for a condition called marine photic zone euxinia (PZE) as a globally important extinction mechanism for the end-Triassic extinction, also called Triassic-Jurassic extinction (201.3 million years ago).

Life of the Triassic met a choking end in a runaway greenhouse climate, heating the seas into warm stagnation. The greenhouse was caused by carbon dioxide released by massive outpourings of basalt from fissure eruptions associated with the opening of the Atlantic Ocean. The resulting boom in marine microbes consumed oxygen and released poisonous hydrogen sulfide into water and air, creating ‘dead zones’ above and below, worldwide. Hydrogen sulfide poisoning is detected by molecular fossils, depicted in lenses. Image credit: Victor Leshyk.

PZE occurs when the sun-lit surface waters of the ocean become devoid of oxygen and are poisoned by hydrogen sulfide – a by-product of microorganisms that live without oxygen that is extremely toxic to most other life forms.

Several previous studies have reported evidence of PZE from terrestrial and shallow environments during the latest Triassic, but the new study, published online in the journal Geology, is the first to provide such evidence from an open ocean setting, indicating these changes may have occurred on a global scale.

Prof Whiteside’s team studied fossilized organic molecules extracted from sedimentary rocks that originally accumulated on the bottom of the north-eastern Panthalassa, but are now exposed on the Queen Charlotte Islands, Canada.

The scientists found molecules derived from photosynthesizing brown-pigmented green sulfur bacteria – microorganisms that only exist under severely anoxic conditions – proving severe oxygen depletion and hydrogen sulfide poisoning of the upper ocean at the end of Triassic.

They also documented marked changes in the nitrogen composition of organic matter, indicating that disruptions in marine nutrient cycles coincided with the development of low oxygen conditions.

“As tectonic plates shifted to break up Pangaea, huge volcanic rifts would have spewed carbon dioxide into the atmosphere, leading to rising temperatures from the greenhouse effect,” Prof Whiteside explained.

“The rapid rises in carbon dioxide would have triggered changes in ocean circulation, acidification and deoxygenation.”

“These changes have the potential to disrupt nutrient cycles and alter food chains essential for the survival of marine ecosystems,” she added. “Our data now provide direct evidence that anoxic, and ultimately euxinic, conditions severely affected food chains.”

“The same carbon dioxide rise that led to the oxygen depleted oceans also led to a mass extinction on land, and ultimately to the ecological take-over by dinosaurs, although the mechanisms are still under study,” Prof Whiteside said.

Courtesy: Alex H. Kasprak et al. 2015. Episodic photic zone euxinia in the northeastern Panthalassic Ocean during the end-Triassic extinction. Geology, vol. 43, no. 4, pp. 307-310; doi: 10.1130/G36371.1 and article by editors Sci-news.com

Key: WFS,Riffin T Sajeev,Russel T sajeev,World Fossil Society,Panthalassa

Plant fossils from Terani clay bed

January 3rd, 2016

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The Upper Gondwana sediments known as “Sivaganga Formation”, represents the first phase of sedimentation in the Cauvery basin. Outcrops are scanty and isolated due to alluvial cover, rarely exceeds 2km in width and at places less than 50m. The upper Gondwana in Tiruchirapalli area is divisible into two formations – the lower Boulder Conglomerate – Sandstone and the upper Terani Clay.
The lower unit is well exposed at Kovandakurichchi quarry, also about 1.5km ENE of Uttatur; and 1.5km NE of Terani and Karai. It is a clast supported framework, some of the clasts exceeding one metre in diameter, comprising of pink, buff colored feldspar, quartz mostly sub-angular to sub-rounded, boulders, cobbles and pebbles of Archean gneissic basement suite; inverse graded bedding (coarsening up) is conspicuous at Kovandakurichchi quarry, Dalmiapuram. This member rests on the Archean Crystallines and grades upward gradually into ferruginous gritty sandstone, siltstone with clay towards the top (Teranipalayam).
The upper unit is known as “Terani Clay beds”. These clays are dirty white, yellowish brown, thin to thick bedded with intervening medium to coarse grained friable, limonitic/ferruginous sandstones with parallel bedding. At places show sharp planar to erosive bases and faulted contacts. Clays are very soft, soapy, 6” to 2’ thick, rich in plant fossils. The plant fossils are represented by several families such as
i) Filicates – Cladophlebis indica, Actinopteris;
ii) Cycadophyta – Ptillophyllum acutifolicum iii) Coniferals-Elatocladus fonferta etc.

Courtesy: Field Visit page of International conference on geo science and environment,January-2016

Key: Terani,WFS,Riffin T Sajeev,Russel T sajeev,World Fossil Society

Rajasree & Russel T sajeev in fossil hunt in terani ( Near Karai formation) (C)World Fossil Society(2011)

Rajasree ,Riffin T Sajeev & Russel T sajeev in fossil hunt in terani ( Near Karai formation) (C)World Fossil Society(2011)

Riffin T Sajeev & Russel T sajeev in fossil hunt in terani ( Near Karai formation) (C)World Fossil Society(2011)

Rajasree ,Riffin T Sajeev & Russel T sajeev in fossil hunt in terani ( Near Karai formation)(2011)

Volcanic chain underlies Antarctica

January 1st, 2016

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Planetary scientists would be thrilled if they could peel Earth like an orange and look at what lies beneath the thin crust. We live on the planet’s cold surface, but Earth is a solid body and the surface is continually deformed, split, wrinkled and ruptured by the roiling of warmer layers beneath it.The contrast between the surface and the depth is nowhere starker — or more important — than in Antarctica. What is causing the mysterious line of volcanoes that emerge from the ice sheet there, and what does it mean for the future of the ice?

“Our understanding of what’s going on is really hampered because we can’t see the geology,” said Andrew Lloyd, a graduate student in earth and planetary sciences in Arts & Sciences at Washington University in St. Louis. “We have to turn to geophysical methods, such as seismology, to learn more,” he said.

Lloyd helped deploy research seismometers across the West Antarctic Rift System and Marie Byrd Land in the austral summer of 2009-10. He then returned in late 2011 and snowmobiled more than 1,000 miles, living in a Scott tent, to recover the precious data.

The recordings the instruments made of the reverberations of distant earthquakes from January 2010 to January 2012 were used to create maps of seismic velocities beneath the rift valley. An analysis of the maps was published online in the Journal of Geophysical Research: Solid Earth.This is the first time seismologists have been able to deploy instruments rugged enough to survive a winter in this part of the frozen continent, and so this is the first detailed look at Earth beneath this region.

The topography of West Antarctica below the ice sheet as viewed from above, looking toward the Antarctic Peninsula. Much of West Antarctica is a basin that lies below sea level (blue), although it is currently filled with ice, not water. West Antarctica was stretched and thinned as it moved away from East Antarctica, forming one of the world’s largest continental rift systems.Credit: Bedrock Consortium

Not surprisingly, the maps show a giant blob of superheated rock about 60 miles beneath Mount Sidley, the last of a chain of volcanic mountains in Marie Byrd Land at one end of the transect. More surprisingly, they reveal hot rock beneath the Bentley Subglacial Trench, a deep basin at the other end of the transect.

The Bentley Subglacial Trench is part of the West Antarctic Rift System and hot rock beneath the region indicates that this part of the rift system was active quite recently.

A volcanic mystery

Mount Sidley, the highest volcano in Antarctica, sits directly above a hot region in the mantle, Lloyd said. Mount Sidley is the southernmost mountain in a volcanic mountain range in Marie Byrd Land, a mountainous region dotted with volcanoes near the coast of West Antarctica.

“A line of volcanoes hints there might be a hidden mantle plume, like a blowtorch, beneath the plate,” said Doug Wiens, PhD, professor of earth and planetary sciences and a co-author on the paper. “The volcanoes would pop up in a row as the plate moved over it.”

“But it’s a bit unclear if this is happening here,” he said. We think we know which direction the plate is moving, but the volcanic chain is going in a different direction and two additional nearby volcanic chains are oriented in yet other directions.

“If this was just a plate moving over a couple of mantle plumes, you’d expect them to line up, as they do in the Hawaiian Islands,” he said.

Although the hot zone’s shape is ill-defined, it is clear there is higher heat flow into the base of the ice sheet in this area, Wiens said.

Deeper than the Grand Canyon

The most interesting finding, Lloyd said, is the discovery of a hot zone beneath the Bentley Subglacial Trench.The basin is part of the West Antarctic Rift System, a series of rifts, adjacent to the Transantarctic Mountains, along which the continent was stretched and thinned.The old rock of East Antarctica rises well above sea level, but west of the Transantarctic Mountains, extension has pulled the crust into a broad saddle, or rift valley, much of which lies a kilometer below sea level.

“If you removed the ice, West Antarctica would rebound, and most of it would be near sea level. But the narrower and deeper basins might remain below it,” Lloyd said. “The Bentley Subglacial Trench, which is the lowest point on Earth not covered by an ocean, would still be a kilometer and a half below sea level if the ice were removed.”

Because the West Antarctic Rift is hidden, less is known about it than about other famous rift systems such as the East African Rift or, in the United States, the Rio Grande Rift.

“We didn’t know what we’d find beneath the basin,” Wiens said. “For all we knew it would be old and cold.

“We didn’t detect any earthquakes, so we don’t think the rift is currently active, but the heat suggests rifting stopped quite recently.”

In this way, it resembles the Rio Grande Rift, which is also no longer active but has yet to cool completely.

A period of diffuse extension created the rift valley in the late Cretaceous, roughly 100 million years ago, Lloyd said, and more focused extension then created deep basins like the Bentley Subglacial Basin and the Terror Rift in the Ross Sea.

“This period of more focused extension likely occurred in the Neogene,” Lloyd said. “If it’s still hot there, it might also be hot under other basins in the rift system.”

Will the heat flow grease the skids?

The rift system is thought to have a major influence on ice streams in West Antarctica. “Rifting and ice flow occur on completely different time scales,” Lloyd said, “so rifting is not going to suddenly make the ice sheet unstable.

“But to accurately model how quickly the ice is going to flow or the rock to rebound, we need to understand the ‘boundary conditions’ for ice models, such as heat flow from the mantle,” he said.

“Seismic surveys like this one will help inform models of the ice sheet,” Wiens said. “Modelers need an estimate of the heat flow, and they need to know something about the geological conditions at the bottom of the ice sheet in order to estimate drag. Right now, both of these factors are very poorly constrained.”

While heat flow through Earth’s crust has been measured at at least 34,000 different spots around the globe, in Antarctica it has been measured in less than a dozen places. In July 2015, scientists reported the heat flow at one of these spots was four times higher than the global average.

Ever since then, scientists have been wondering why the reading was so high. “Recent extension in the Bentley Subglacial Trench might explain these readings,” Wiens said.

The next big problem, he said, is to understand the structure under the Thwaites and Pine Island glaciers, which lie closer to the coastline than the Bentley Subglacial Trench. These two glaciers have been described as the ‘weak underbelly’ of the ice sheet because surges in the ice flow there could theoretically cause the rapid disintegration of the entire West Antarctic ice sheet.

During the 2014-2015 Antarctic field season, Lloyd helped deploy another 10 seismic stations that together with seismometers deployed by the British will map the underside of this key area.

Ref: Washington University in St. Louis. “Hot rock and ice: Volcanic chain underlies Antarctica: Seismic maps of the mantle will improve predictions of giant ice sheet’s fate.” ScienceDaily. ScienceDaily, 8 December 2015. <www.sciencedaily.com/releases/2015/12/151208134632.htm

Key:WFS,Riffin T Sajeev,Russel T Sajeev,World Fossil Society,Volcanic chain , Antarctica