This image shows the dorsal view of Fuxianhuia protensa. The three-inch-long fossil was found in sediments dating from the Cambrian Period 520 million years ago in what today is the Yunnan province in China. Parts of the gut are visible as dark stains along the animal’s midline. Credit: Xiaoya Ma
In 520 million-year-old fossil deposits resembling an ‘invertebrate version of Pompeii,’ researchers have found an ancestor of modern crustaceans revealing the first-known cardiovascular system in exquisitely preserved detail
An international team of researchers from the University of Arizona, China and the United Kingdom has discovered the earliest known cardiovascular system, and the first to clearly show a sophisticated system complete with heart and blood vessels, in fossilized remains of an extinct marine creature that lived over half a billion years ago. The finding sheds new light on the evolution of body organization in the animal kingdom and shows that even the earliest creatures had internal organizational systems that strongly resemble those found in their modern descendants.
“This is the first preserved vascular system that we know of,” said Nicholas Strausfeld, a Regents’ Professor of Neuroscience at the University of Arizona’s Department of Neuroscience, who helped analyze the find.
Being one of the world’s foremost experts in arthropod morphology and neuroanatomy, Strausfeld is no stranger to finding meaningful and unexpected answers to long-standing mysteries in the remains of creatures that went extinct so long ago scientists still argue over where to place them in the evolutionary tree.
The 3-inch-long fossil was entombed in fine dustlike particles – now preserved as fine-grain mudstone – during the Cambrian Period 520 million years ago in what today is the Yunnan province in China. Found by co-author Peiyun Cong near Kunming, it belongs to the species Fuxianhuia protensa, an extinct lineage of arthropods combining advanced internal anatomy with a primitive body plan.
“Fuxianhuia is relatively abundant, but only extremely few specimens provide evidence of even a small part of an organ system, not even to speak of an entire organ system,” said Strausfeld, who directs the UA Center for Insect Science. “The animal looks simple, but its internal organization is quite elaborate. For example, the brain received many arteries, a pattern that appears very much like a modern crustacean.”
In fact, Strausfeld pointed out, Fuxianhuia’s vascular system is more complex than what is found in many modern crustaceans.
“It appears to be the ground pattern from which others have evolved,” he said. “Different groups of crustaceans have vascular systems that have evolved into a variety of arrangements but they all refer back to what we see in Fuxianhuia.”
“Over the course of evolution, certain segments of the animals’ body became specialized for certain things, while others became less important and, correspondingly, certain parts of the vascular system became less elaborate,” Strausfeld said.
Strausfeld helped identify the oldest known fossilized brain in a different specimen of the same fossil species, as well as the first evidence of a completely preserved nervous system similar to that of a modern chelicerates, such as a horseshoe crab or a scorpion.
“This is another remarkable example of the preservation of an organ system that nobody would have thought could become fossilized,” he said.
In addition to the exquisitely preserved heart and blood vessels, outlined as traces of carbon embedded in the surrounding mineralized remains of the fossil, it also features the eyes, antennae and external morphology of the animal.
Using a clever imaging technique that selectively reveals different structures in the fossil based on their chemical composition, collaborator Xiaoya Ma at London’s Natural History Museum was able to identify the heart, which extended along the main part of the body, and its many lateral arteries corresponding to each segment. Its arteries were composed of carbon-rich deposits and gave rise to long channels, which presumably took blood to limbs and other organs.
“With that, we can now start speculating about behavior,” Strausfeld explained. “Because of well-supplied blood vessels to its brain, we can assume this was a very active animal capable of making many different behavioral choices.”
Researchers can only speculate as to why the chemical reactions that occurred during the process of fossilization allowed for this unusual and rare kind of preservation, and as to why only select tissues were preserved between a few rare and different specimen.
“Presumably the conditions had to be just right,” Strausfeld said. “We believe that these animals were preserved because they were entombed quickly under very fine-grained deposits during some kind of catastrophic event, and were then permeated by certain chemicals in the water while they were squashed flat. It is an invertebrate version of Pompeii.”
Possibly, only one in thousands of fossils might have such a well-preserved organ system, Strausfeld said.
At the time Fuxianhuia crawled on the seafloor or swam through water, life had not yet conquered land.
“Terrible sand storms must have occurred because there were probably no plants that could hold the soils,” Strausfeld said. “The habitats of these creatures must have been inundated with massive fallouts from huge storms.”
Tsunamis may also be the cause for the exceptional preservation.
“As the water withdraws, animals on the seafloor dry,” Strausfeld said. “When the water rushed back in, they might become inundated with mud. Under normal circumstances, when animals die and are left to rot on the seafloor, they become unrecognizable. What happened to provide the kinds of fossils we are seeing must have been very different.”
Note : Note : The above story is based on materials provided by University of Arizona
Subdivision of the Triassic system according to the IUGS, as of July 2012.
The Early Triassic is the first of three epochs of the Triassic Period of the geologic timescale. It spans the time between 252.2 ± 0.5 Ma and 247.2 Ma (million years ago). Rocks from this epoch are collectively known as the Lower Triassic, which is a unit in chronostratigraphy. The Early Triassic is the oldest epoch of the Mesozoic Era and is divided into the Induan and Olenekian ages.
The Lower Triassic series is coeval with the Scythian stage, which is today not included in the official timescales but can be found in older literature. In Europe, most of the Lower Triassic is composed of Buntsandstein, a lithostratigraphic unit of continental red beds.
The Permian-Triassic extinction event spawned the Triassic period. The massive extinctions that ended the Permian period and Paleozoic era caused extreme hardships for the surviving species. Many types of corals, brachiopods, molluscs, echinoderms, and other invertebrates had completely disappeared. The most common Early Triassic hard-shelled marine invertebrates were bivalves, gastropods, ammonites, echinoids, and a few articulate brachiopods. The most common land animal was the small herbivorous synapsid Lystrosaurus.
Early Triassic faunas lacked biodiversity and were relatively homogenous throughout the epoch due to the effects of the extinction, ecological recovery on land took 30M years. The climate during the Early Triassic epoch (especially in the interior of the supercontinent Pangaea) was generally arid, rainless and dry and deserts were widespread however the poles possessed a temperate climate. The relatively hot climate of the Early Triassic may have been caused by widespread volcanic eruptions which accelerated the rate of global warming and possibly caused the Permian Triassic extinction event.
Smithian-Spathian extinction
Until recently the existence of an extinction event about 3 million years following the end-Permian extinctions was not recognised, possibly because there were few species left to go extinct. However, studies on conodonts have revealed that temperatures rose in the first 3 million years of the Triassic, ultimately reaching sea surface temperatures of 40 °C in the tropics around 249 million years ago. Large and mobile species disappeared from the tropics, and amongst the immobile species such as molluscs only the ones that could cope with the heat survived; half the bivalves disappeared. On land the tropics were practically devoid of life.
Big, active animals only returned to the tropics, and plants recolonised on land when temperatures returned to normal around 247 million years ago.
Subdivision of the Triassic system according to the IUGS, as of July 2012.
In the geologic timescale, the Middle Triassic is the second of three epochs of the Triassic period or the middle of three series in which the Triassic system is divided. It spans the time between 247.2 Ma and ~235 Ma (million years ago). The Middle Triassic is divided into the Anisian and Ladinian ages or stages.
Formerly the middle series in the Triassic was also known as Muschelkalk. This name is now only used for a specific unit of rock strata with approximately Middle Triassic age, found in western Europe.
During this time there were no flowering plants, but instead there were ferns and mosses. Small dinosaurs began to appear like Nyasasaurus.
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Subdivision of the Triassic systemaccording to the IUGS, as of July 2012.
The Late Triassic is in the geologic timescale the third and final of three epochs of the Triassic period. The corresponding series is known as the Upper Triassic. In the past it was sometimes called the Keuper, after a German lithostratigraphic group (a sequence of rock strata) that has a roughly corresponding age. The Late Triassic spans the time between ~235 Ma and 201.3 ± 0.2 Ma (million years ago). The Late Triassic is divided into the Carnian, Norian and Rhaetian ages.
Many of the first dinosaurs evolved during the Late Triassic, including Plateosaurus, Coelophysis, and Eoraptor.
Paleogeography and tectonics
Africa shared Pangea’s relatively uniform fauna which was dominated by theropods, prosauropods and primitive ornithischians by the close of the Triassic period. Late Triassic fossils are found throughout Africa, but are more common in the south than north.
The boundary separating the Triassic and Jurassic marks the advent of an extinction event with global impact, although African strata from this time period have not been thoroughly studied. In the area of Tübingen (Germany), a Triassic-Jurassic bonebed can be found, which is characteristic for this boundary.
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The Triassic /traɪˈæsɪk/ is a geologic period and system that extends from about 250 to 200 Ma (252.2 ± 0.5 to 201.3 ± 0.2 million years ago). It is the first period of the Mesozoic Era, and lies between the Permian and Jurassic periods. Both the start and end of the period are marked by major extinction events. The Triassic was named in 1834 by Friedrich von Alberti, after the three distinct rock layers (tri meaning “three”) that are found throughout Germany and northwestern Europe—red beds, capped by marine limestone, followed by a series of terrestrial mud- and sandstones—called the “Trias.”
The Triassic began in the wake of the Permian–Triassic extinction event, which left the Earth’s biosphere impoverished; it would take well into the middle of the period for life to recover its former diversity. Therapsids and archosaurs were the chief terrestrial vertebrates during this time. A specialized subgroup of archosaurs, dinosaurs, first appeared in the Late Triassic but did not become dominant until the succeeding Jurassic. The first true mammals, themselves a specialized subgroup of Therapsids also evolved during this period, as well as the first flying vertebrates, the pterosaurs, who like the dinosaurs were a specialized subgroup of archosaurs. The vast supercontinent of Pangaea existed until the mid-Triassic, after which it began to gradually rift into two separate landmasses, Laurasia to the north and Gondwana to the south. The global climate during the Triassic was mostly hot and dry, with deserts spanning much of Pangaea’s interior. However, the climate shifted and became more humid as Pangaea began to drift apart. The end of the period was marked by yet another major mass extinction, wiping out many groups and allowing dinosaurs to assume dominance in the Jurassic.
Dating and subdivisions
The Triassic is usually separated into Early, Middle, and Late Triassic Epochs, and the corresponding rocks are referred to as Lower, Middle, or Upper Triassic. The faunal stages from the youngest to oldest are:
)During the Triassic, almost all the Earth’s land mass was concentrated into a single supercontinent centered more or less on the equator, called Pangaea (“all the land”). From the east a vast gulf entered Pangaea, the Tethys sea. It opened farther westward in the mid-Triassic, at the expense of the shrinking Paleo-Tethys Ocean, an ocean that existed during the Paleozoic. The remaining shores were surrounded by the world-ocean known as Panthalassa (“all the sea”). All the deep-ocean sediments laid down during the
Triassic have disappeared through subduction of oceanic plates; thus, very little is known of the Triassic open ocean. The supercontinent Pangaea was rifting during the Triassic—especially late in the period—but had not yet separated. The first nonmarine sediments in the rift that marks the initial break-up of Pangaea—which separated New Jersey from Morocco—are of Late Triassic age; in the U.S., these thick sediments comprise the Newark Group. Because of the limited shoreline of one super-continental mass, Triassic marine deposits are globally relatively rare, despite their prominence in Western Europe, where the Triassic was first studied. In North America, for example, marine deposits are limited to a few exposures in the west. Thus Triassic stratigraphy is mostly based on organisms living in lagoons and hypersaline environments, such as Estheria crustaceans.
Africa
At the beginning of the Mesozoic Era, Africa was joined with Earth’s other continents in Pangaea. Africa shared the supercontinent’s relatively uniform fauna which was dominated by theropods, prosauropods and primitive ornithischians by the close of the Triassic period. Late Triassic fossils are found throughout Africa, but are more common in the south than north. The boundary separating the Triassic and Jurassic marks the advent of an extinction event with global impact, although African strata from this time period have not been thoroughly studied.
South America
At Paleorrota geopark, located in Rio Grande do Sul, Brazil, the Santa Maria Formation and Caturrita Formations are exposed. In these formations, one of the earliest dinosaurs, Staurikosaurus, as well as the mammal ancestors Brasilitherium and Brasilodon have been discovered.
Climate
The Triassic climate was generally hot and dry, so that typical deposits are red bed sandstones and evaporites. There is no evidence of glaciation at or near either pole; in fact, the polar regions were apparently moist and temperate, a climate suitable for forests and vertebrates, including reptiles. Pangaea’s large size limited the moderating effect of the global ocean; its continental climate was highly seasonal, with very hot summers and cold winters. The strong contrast between the Pangea supercontinent and the global ocean triggered intense cross-equatorial monsoons.
Although the Triassic may have mostly been a dry period, at least at tropical and subtropical latitudes in the Tethys and surrounding lands, evidence exists that it was punctuated by several episodes of increased rainfall. Sediments and fossils suggestive of a more humid climate are known from the Anisian to Ladinian of the Tethysian domain, and from the Carnian and Rhaetian of a larger area that includes also the Boreal domain (e.g., Svalbard Islands), the North American continent, the South China block and Argentina.
The best studied of such episodes of humid climate, and probably the most intense and widespread, was the Carnian Pluvial Event
Life
Life restaurations of some Triassic plants
Three categories of organisms can be distinguished in the Triassic record: holdovers from the Permian-Triassic extinction, new groups which flourished briefly, and other new groups which went on to dominate the Mesozoic world.
Flora
On land, the holdover plants included the lycophytes, the dominant cycads, ginkgophyta (represented in modern times by Ginkgo biloba) and glossopterids. The spermatophytes, or seed plants came to dominate the terrestrial flora: in the northern hemisphere, conifers flourished. Glossopteris (a seed fern) was the dominant southern hemisphere tree during the Early Triassic period.
Marine fauna
In marine environments, new modern types of corals appeared in the Early Triassic, forming small patches of reefs of modest extent compared to the great reef systems of Devonian times or modern reefs. Serpulids appeared in the Middle Triassic. Microconchids were abundant. The shelled cephalopods called ammonites recovered, diversifying from a single line that survived the Permian extinction. The fish fauna was remarkably
uniform, reflecting the fact that very few families survived the Permian extinction. There were also many types of marine reptiles. These included the Sauropterygia, which featured pachypleurosaurs and nothosaurs (both common during the Middle Triassic, especially in the Tethys region), placodonts, and the first plesiosaurs; the first of the lizardlike Thalattosauria (askeptosaurs); and the highly successful ichthyosaurs, which appeared in Early Triassic seas and soon diversified, some eventually developing to huge size during the late Triassic.
Terrestrial fauna
Important groups of terrestrial fauna, newly in the triassic period or achieving a new level of evolutionary success during the triassic include:
Temnospondyls
One of the largest and most important groups of early amphibians, temnospondyls originated during the Carboniferous but flourished during the Triassic. They lived across the globe, ranged in size from tiny to enormous and prospered both on land and in the water. The largest temnospondyls, such as the Mastodonsaurus were up to 13ft in length.
Rhynchosaurs
These barrel-gutted herbivores thrived for only a short period of time, becoming extinct about 220 million years ago, but they were exceptionally abundant and were the primary large herbivores in many ecosystems. They sheared plants with their beaks and several rows of teeth on the roof of the mouth.
Phytosaurs
One of the most familiar of the crocodile-line archosaurs, phytosaurs prospered during the late Triassic. These long-snouted and semiaquatic predators resemble living crocodiles and probably had a similar lifestyle, hunting for fish and small reptiles around the water’s edge. However this resemblance is only superficial and is a prime-case of convergent evolution.
Aetosaurs
Like the phytosaurs, aetosaurs were exceptionally common during the last 30 million years of the late Triassic but died out at the Triassic-Jurassic extinction. Aetosaurs were heavily armored and resembled giant military tanks. Most aetosaurs were herbivorous, and fed on low-growing plants but some may have eaten meat.
Rauisuchians
The rauisuchians, yet another group of crocodile-line archosaurs, were the keystone predators of most Triassic terrestrial ecosystems. Over 25 species have been found, and include giant quadripedal hunters, sleeks bipedal omnivores, and lumbering beasts with deep sails on their backs. They probably occupied the large-predator niche later filled by theropods.
Theropods
Perhaps the most recognizable group of dinosaurs, the therapods include predators such as the Tyrannosaurus, Allosaurus, and Velociraptor. Theropods first evolved in the Triassic period but did not evolve into giant sizes until later, during the Jurassic. Most Triassic theropods, such as the Coelophysis, were only several feet long and hunted small prey in the shadow of the giant Rauisuchians.
Cynodonts
Cynodonts are a large group that includes true mammals. The first cynodonts evolved in the Permian, but many groups prospered during the Triassic. Their characteristic mammalian features included hair, a large brain, and upright posture. Many were small but some were enormous and filled a large herbivore niche before the evolution of sauropodomorph dinosaurs.
The Permian-Triassic extinction devastated terrestrial life. Biodiversity rebounded with the influx of pioneer organisms, but these were short lived. Diverse communities with complex trophic structures took 30 million years to reestablish.
Temnospondyl amphibians were among those groups that survived the Permian-Triassic extinction, some lineages (e.g. trematosaurs) flourishing briefly in the Early Triassic, while others (e.g. capitosaurs) remained successful throughout the whole period, or only came to prominence in the Late Triassic (e.g. plagiosaurs, metoposaurs). As for other amphibians, the first Lissamphibia, characterized by the first frogs, are known from the Early Triassic, but the group as a whole did not become common until the Jurassic, when the temnospondyls had become very rare. Other survivors were the Chroniosuchia and Embolomeri, more closely related to amniotes than temnospondyls, but went extinct after some million years.
Archosauromorph reptiles—especially archosaurs—progressively replaced the synapsids that had dominated the Permian, although Cynognathus was a characteristic top predator in earlier Triassic (Olenekian and Anisian) Gondwana, and both kannemeyeriid dicynodonts and gomphodont cynodonts remained important herbivores during much of the period. By the end of the Triassic, synapsids played only bit parts. During the Carnian (early part of the Late Triassic), some advanced cynodont gave rise to the first mammals. At the same time the Ornithodira, which until then had been small and insignificant, evolved into pterosaurs and a variety of dinosaurs. The Crurotarsi were the other important archosaur clade, and during the Late Triassic these also reached the height of their diversity, with various groups including the phytosaurs, aetosaurs, several distinct lineages of Rauisuchia, and the first crocodylians (the Sphenosuchia). Meanwhile the stocky herbivorous rhynchosaurs and the small to medium-sized insectivorous or piscivorous Prolacertiformes were important basal archosauromorph groups throughout most of the Triassic.
Among other reptiles, the earliest turtles, like Proganochelys and Proterochersis, appeared during the Norian (middle of the Late Triassic). The Lepidosauromorpha—specifically the Sphenodontia—are first known in the fossil record a little earlier (during the Carnian). The Procolophonidae were an important group of small lizard-like herbivores.
In the Triassic, archosaurs displaced therapsids as the dominant amniotes. This “Triassic Takeover” may have contributed to the evolution of mammals by forcing the surviving therapsids and their mammaliaform successors to live as small, mainly nocturnal insectivores; nocturnal life may have forced the mammaliaforms to develop fur and higher metabolic rates.
Coal
At the start of the Triassic period coal is noticeable by geologists today as being absent throughout the world. This is known as the “coal gap” and can be seen as part of the Permian–Triassic extinction event.Sharp drops in sea level across the Permo Triassic boundary may be the proper explanation for the coal gap. However, theories are still speculative as to why it is missing. During the preceding Permian period the arid desert conditions contributed to the evaporation of many inland seas and the inundation of these seas, perhaps by a number of tsunami events that may have been responsible for the drop in sea level. This due to the finding of large salt basins in the southwest United States and a very large basin in central Canada.
Immediately above the boundary the glossopteris flora was suddenly largely displaced by an Australia wide coniferous flora containing few species and containing a lycopod herbaceous under story. Conifers also became common in Eurasia. These groups of conifers arose from endemic species because of the ocean barriers that prevented seed crossing for over one hundred million years. For instance, Podocarpis was located south and Pines, Junipers, and Sequoias were located north. The dividing line ran through the Amazon Valley, across the Sahara, and north of Arabia, India, Thailand, and Australia. It has been suggested that there was a climate barrier for the conifers. although water barriers are more plausible. If so, something that can cross at least short water barriers must have been involved in producing the coal hiatus. Hot climate could have been an important auxiliary factor across Antarctica or the Bering Strait, however. There was a spike of fern and lycopod spores immediately after the close of the Permian. In addition there was also a spike of fungal spores immediately after the Permian-Triassic boundary. This spike may have lasted 50,000 years in Italy and 200,000 years in China and must have contributed to the climate warmth.
An event excluding a catastrophe must have been involved to cause the coal hiatus due to the fact that fungi would have removed all dead vegetation and coal forming detritus in a few decades in most tropical places. In addition, fungal spores rose gradually and declined similarly along with a prevalence of woody debris. Each phenomenon would hint at widespread vegetative death. Whatever the cause of the coal hiatus must have started in North America approximately 25 million years sooner.
Lagerstätten
Triassic sandstone near Stadtroda, Germany
The Monte San Giorgio lagerstätte, now in the Lake Lugano region of northern Italy and Switzerland, was in Triassic times a lagoon behind reefs with an anoxic bottom layer, so there were no scavengers and little turbulence to disturb fossilization, a situation that can be compared to the better-known Jurassic Solnhofen limestone lagerstätte. The remains of fish and various marine reptiles (including the common pachypleurosaur Neusticosaurus, and the bizarre long-necked archosauromorph Tanystropheus), along with some terrestrial forms like Ticinosuchus and Macrocnemus, have been recovered from this locality. All these fossils date from the Anisian/Ladinian transition (about 237 million years ago).
Triassic-Jurassic extinction event
The Triassic period ended with a mass extinction, which was particularly severe in the oceans; the conodonts disappeared, as did all the marine reptiles except ichthyosaurs and plesiosaurs. Invertebrates like brachiopods, gastropods, and molluscs were severely affected. In the oceans, 22% of marine families and possibly about half of marine genera went missing according to University of Chicago paleontologist Jack Sepkoski.
Though the end-Triassic extinction event was not equally devastating everywhere in terrestrial ecosystems, several important clades of crurotarsans (large archosaurian reptiles previously grouped together as the thecodonts) disappeared, as did most of the large labyrinthodont amphibians, groups of small reptiles, and some synapsids (except for the proto-mammals). Some of the early, primitive dinosaurs also went extinct, but other more adaptive dinosaurs survived to evolve in the Jurassic. Surviving plants that went on to dominate the Mesozoic world included modern conifers and cycadeoids.
What caused this Late Triassic extinction is not known with certainty. It was accompanied by huge volcanic eruptions that occurred as the supercontinent Pangaea began to break apart about 202 to 191 million years ago 40Ar/39Ar dates,forming the CAMP, one of the largest known inland volcanic events since the planet cooled and stabilized. Other possible but less likely causes for the extinction events include global cooling or even a bolide impact, for which an impact crater containing Manicouagan Reservoir in Quebec, Canada, has been singled out. At the Manicouagan impact crater, however, recent research has shown that the impact melt within the crater has an age of 214±1 Mya. The date of the Triassic-Jurassic boundary has also been more accurately fixed recently, at 201.3 ± 0.2 Mya. Both dates are gaining accuracy by using more accurate forms of radiometric dating, in particular the decay of uranium to lead in zircons formed at the impact. So the evidence suggests the Manicouagan impact preceded the end of the Triassic by approximately 10±2 Ma. Therefore it could not be the immediate cause of the observed mass extinction.
The number of Late Triassic extinctions is disputed. Some studies suggest that there are at least two periods of extinction towards the end of the Triassic, between 12 and 17 million years apart. But arguing against this is a recent study of North American faunas. In the Petrified Forest of northeast Arizona there is a unique sequence of latest Carnian-early Norian terrestrial sediments. An analysis in 2002 found no significant change in the paleoenvironment. Phytosaurs, the most common fossils there, experienced a change-over only at the genus level, and the number of species remained the same. Some aetosaurs, the next most common tetrapods, and early dinosaurs, passed through unchanged. However, both phytosaurs and aetosaurs were among the groups of archosaur reptiles completely wiped out by the end-Triassic extinction event.
It seems likely then that there was some sort of end-Carnian extinction, when several herbivorous archosauromorph groups died out, while the large herbivorous therapsids— the kannemeyeriid dicynodonts and the traversodont cynodonts—were much reduced in the northern half of Pangaea (Laurasia).
These extinctions within the Triassic and at its end allowed the dinosaurs to expand into many niches that had become unoccupied. Dinosaurs became increasingly dominant, abundant and diverse, and remained that way for the next 150 million years. The true “Age of Dinosaurs” is the Jurassic and Cretaceous, rather than the Triassic.
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Global perspective: satellites are often the only form of monitoring for remote or inaccessible volcanoes. This view shows some of the recent episodes of deformation seen at volcanoes in Europe and Africa. Credit: Image courtesy of University of Bristol
ESA’s Sentinel satellite, due for launch on April 3rd, should allow scientists to test this link in greater detail and eventually develop a forecast system for all volcanoes, including those that are remote and inaccessible.
Volcano deformation and, in particular, uplift are often considered to be caused by magma moving or pressurizing underground. Magma rising towards the surface could be a sign of an imminent eruption. On the other hand, many other factors influence volcano deformation and, even if magma is rising, it may stop short, rather than erupting.
Dr Juliet Biggs and colleagues in the School of Earth Sciences, with collaborators from Cornell, Oxford and Southern Methodist University, looked at the archive of satellite data covering over 500 volcanoes worldwide, many of which have been systematically observed for over 18 years. Satellite radar (InSAR) can provide high-resolution maps of deformation, allowing the detection of unrest at many volcanoes that might otherwise go unrecognised. Such satellite data is often the only source of information for remote or inaccessible volcanoes.
The researchers applied statistical methods more traditionally used for medical diagnostic testing and found that many deforming volcanoes also erupted (46 per cent). Together with the very high proportion of non-deforming volcanoes that did not erupt (94 per cent), these jointly represent a strong indicator of a volcano’s long-term eruptive potential.
Dr Biggs said: “The findings suggest that satellite radar is the perfect tool to identify volcanic unrest on a regional or global scale and target ground-based monitoring.”
The work was co-funded by the UK Centre for Observation and Modelling of Earthquakes, Volcanoes and Tectonics (COMET) and STREVA, a research consortium aimed at finding ways to reduce the negative consequences of volcanic activity on people and their assets.
“Improving how we anticipate activity using new technology such as this is an important first step in doing better at forecasting and preparing for volcanic eruptions,” said STREVA Principal Investigator, Dr Jenni Barclay.
Co-author Professor Willy Aspinall added: “Global studies of volcano deformation using satellite data will increasingly play a part in assessing eruption potential at more and more volcanoes, especially in regions with short historical records or limited conventional monitoring.”
However, many factors and processes, some observable, but others not, influence deformation to a greater or lesser extent. These include the type of rock that forms the volcano, its tectonic characteristics and the supply rate and storage depth of magma beneath it. Thus, deformation can have different implications for different types of volcanoes. For volcanoes with short eruption cycles, the satellite record typically spans episodes that include both deformation and eruption, resulting in a high correlation between the two. For volcanoes with long eruption cycles, the satellite record tends to capture either deformation or eruption but rarely both.
In the past, radar images of the majority of the world’s volcanoes were only acquired a few times a year, but seismological data indicate that the duration of unrest before an eruption might be as short as only a few days.
Dr Biggs said: “This study demonstrates what can be achieved with global satellite coverage even with limited acquisitions, so we are looking forward to the step-change in data quantity planned for the next generation of satellites.”
The European Space Agency is planning to launch its next radar mission, Sentinel-1 in early April. This mission is designed for global monitoring and will collect images every six to twelve days. Using this, scientists should be able to test the causal and temporal relationship with deformation on much shorter timescales.
Professor Tim Wright, Director of COMET, added: “This study is particularly exciting because Sentinel-1 will soon give us systematic observations of the ups and downs of every volcano on the planet. For many places, particularly in developing countries, these data could provide the only warning of an impending eruption.”
Note : The above story is based on materials provided by University of Bristol.
Temperature, not chemistry. What appears on the surface correlates with temperature deep in the Earth. Higher ridge elevation indicates a hotter mantle — as in Iceland, above, which also appears to sit atop a mantle plume, a vertical jet of hot rock originating from deep in the Earth. Credit: Allison Gale/University of Wisconsin
Scientists have shown that temperature differences deep within Earth’s mantle control the elevation and volcanic activity along mid-ocean ridges, the colossal mountain ranges that line the ocean floor. The findings, published April 4 in the journal Science, shed new light on how temperature in the depths of the mantle influences the contours of Earth’s crust.
Mid-ocean ridges form at the boundaries between tectonic plates, circling the globe like seams on a baseball. As the plates move apart, magma from deep within Earth rises up to fill the void, creating fresh crust as it cools. The crust formed at these seams is thicker in some places than others, resulting in ridges with widely varying elevations. In some places, the peaks are submerged miles below the ocean surface. In other places — Iceland, for example — the ridge tops are exposed above the water’s surface.
“These variations in ridge depth require an explanation,” said Colleen Dalton, assistant professor of geological sciences at Brown and lead author of the new research. “Something is keeping them either sitting high or sitting low.”
That something, the study found, is the temperature of rocks deep below Earth’s surface.
By analyzing the speeds of seismic waves generated by earthquakes, the researchers show that mantle temperature along the ridges at depths extending below 400 kilometers varies by as much as 250 degrees Celsius. High points on the ridges tend to be associated with higher mantle temperatures, while low points are associated with a cooler mantle. The study also showed that volcanic hot spots along the ridge — volcanoes near Iceland as well as the islands of Ascension, Tristan da Cunha, and elsewhere — all sit above warm spots in Earth’s mantle.
“It is clear from our results that what’s being erupted at the ridges is controlled by temperature deep in the mantle,” Dalton said. “It resolves a long-standing controversy and has not been shown definitively before.”
A CAT scan of Earth
The mid-ocean ridges provide geologists with a window to the interior of Earth. The ridges form when mantle material melts, rises into the cracks between tectonic plates, and solidifies again. The characteristics of the ridges provide clues about the properties of the mantle below.
For example, a higher ridge elevation suggests a thicker crust, which in turn suggests that a larger volume of magma was erupted at the surface. This excess molten rock can be caused by very hot temperatures in the mantle. The problem is that hot mantle is not the only way to produce excess magma. The chemical composition of the rocks in Earth’s mantle also controls how much melt is produced. For certain rock compositions, it is possible to generate large volumes of molten rock under cooler conditions. For many decades it has not been clear whether mid-ocean ridge elevations are caused by variations in the temperature of the mantle or variations in the rock composition of the mantle.
To distinguish between these two possibilities, Dalton and her colleagues introduced two additional data sets. One was the chemistry of basalts, the rock that forms from solidification of magma at the mid-ocean ridge. The chemical composition of basalts differs depending upon the temperature and composition of the mantle material from which they’re derived. The authors analyzed the chemistry of nearly 17,000 basalts formed along mid-ocean ridges around the globe.
The other data set was seismic wave tomography. During earthquakes, seismic waves are sent pulsing through the rocks in the crust and mantle. By measuring the velocity of those waves, scientists can gather data about the characteristics of the rocks through which they traveled. “It’s like performing a CAT scan of the inside of the Earth,” Dalton said.
Seismic wave speeds are especially sensitive to the temperature of rocks. In general, waves propagate more quickly in cooler rocks and more slowly in hotter rocks.
Dalton and her colleagues combined the seismic data from hundreds of earthquakes with data on elevation and rock chemistry from the ridges. Correlations among the three data sets revealed that temperature deep in the mantle varied between around 1,300 and 1,550 degrees Celsius underneath about 61,000 kilometers of ridge terrain. “It turned out,” said Dalton, “that seismic tomography was the smoking gun. The only plausible explanation for the seismic wave speeds is a very large temperature range.”
The study showed that as ridge elevation falls, so does mantle temperature. The coolest point beneath the ridges was found near the lowest point, an area of very deep and rugged seafloor known as the Australian-Antarctic discordance in the Indian Ocean. The hottest spot was near Iceland, which is also the ridges’ highest elevation point.
Iceland is also where scientists have long debated whether a mantle plume — a vertical jet of hot rock originating from deep inside Earth — intersects the mid-ocean ridge. This study provides strong support for a mantle plume located beneath Iceland. In fact, this study showed that all regions with above-average temperature are located near volcanic hot spots, which points to mantle plumes as the culprit for the excess volume of magma in these areas.
Understanding a churning planet
Despite being made of solid rock, Earth’s mantle doesn’t sit still. It undergoes convection, a slow churning of material from the depths of the Earth toward the surface and back again.
“Convection is why we have plate tectonics and earthquakes,” Dalton said. “It’s also responsible for almost all volcanism at the surface. So understanding mantle convection is crucial to understanding many fundamental questions about the Earth.”
Two factors influence how that convection works: variations in the composition of the mantle and variations in its temperature. This work, says Dalton, points to temperature as a primary factor in how convection is expressed on the surface.
“We get consistent and coherent temperature measurements from the mantle from three independent datasets,” Dalton said. “All of them suggest that what we see at the surface is due to temperature, and that composition is only a secondary factor. What is surprising is that the data require the temperature variations to exist not only near the surface but also many hundreds of kilometers deep inside the Earth.”
The findings from this study will also be useful in future research using seismic waves, Dalton says. Because the temperature readings as indicated by seismology were backed up by the other datasets, they can be used to calibrate seismic readings for places where geochemical samples aren’t available. This makes it possible to estimate temperature deep in Earth’s mantle all over the globe.
That will help geologists gain a new insights into how processes deep within Earth mold the ground beneath our feet.
Note : The above story is based on materials provided by Brown University.
Microbial consumption dynamics of racemic amino acids (L-enantiomers: open symbol; D-enantiomers: filled symbol) following addition to soils. Credit: Gaosen Zhang
A study published this week in PLOS ONE authored by Dr. Henry Sun and his postdoctoral student Dr. Gaosen Zhang of Nevada based research institute DRI provides new evidence that Earth bacteria can do something that is quite unusual. Despite the fact that these bacteria are made of left-handed (L) amino acids, they are able to grow on right-handed (D) amino acids. This DRI study, funded by the NASA Astrobiology Institute and the NASA Exobiology Program, takes a closer look at what these implications mean for studying organisms on Earth and beyond
“This finding is important because D-amino acids are slowly produced in soils through geochemical transformation of L amino acids. If they were allowed to accumulate, they would poison the environment for plants and animals. Our research shows that it is the bacteria that prevent D-amino acids from accumulating to toxic levels,” explains Dr. Sun, who has studied microbial life in extreme environments in the Antarctic dry valleys, the Atacama Desert, and Death Valley.
Amino acids, the fundamental building blocks of life, come in two forms that, like our left and right hand, have identical parts. But the two forms are not the same from a three dimensional perspective. One is the mirror image of the other. Proteins and enzymes in Earth organisms, without exception, all use L-forms. As expected, soil bacteria are very efficient at consuming L-amino acids from the medium. The researchers then presented the same bacteria D-amino acids. To their surprise, these life-incompatible forms too were rapidly consumed.
“We are not saying that the D-amino acids are assimilated as is. If incorporated into proteins, this amount of D-amino acids would kill the organisms,” says Dr. Sun. “Rather, we think that a conversion occurred in the bacteria that turned the D-amino acids back into L-forms. All bacteria carry a specialized enzyme known as racemase which converts amino acids from one form to another,” adds Dr. Sun.
This then raises another question: If all organisms on Earth synthesize L-amino acids, where do D-amino acids come from? Amino acids have the property of being able to spontaneously flip from one form to another, a process called racemization. Racemization is very slow. Most organisms do not live long enough for this process to kill the proteins and, ultimately, the organisms themselves. In soils, however, amino acids can be sequestered for thousands or even millions of years, allowing racemization to accumulate. Eventually, the concentrated D-amino acids are released into the environments — to the waiting bacteria, rather than poisoning plant and animal life.
Bacteriologists have known that bacteria contain racemases, but they have always assumed that the enzymes were invented for making D-amino acids. Unlike plants and animals, bacteria need a small amount of D-amino acids, not to incorporate into proteins, but to incorporate into cell walls to increase resistance and stability.
“But this cannot be the reason that bacteria invented the racemase. If D-amino acids are toxic, you have to invent a detoxification mechanism first before you go around and make more of the stuff. We think it is much more likely that the racemase originated initially as a detoxification enzyme. Only later, do bacteria, now immune to D-amino acid toxicity, start to make D-amino acids for constructive purposes. The D-amino acid-making function, therefore, is a secondary biological invention,” says Dr. Sun.
“The implications of our study go beyond Earth. The steps that led to the invention of racemases on Earth would also exist on other planets, even if life uses D- instead of L-amino acids. This means that D-bacteria would also have to invent racemases and, as a result, would consume L-amino acids for nutrients. This creates a scenario that scientists charged with the duty of protecting Earth from foreign organisms haven’t thought about,” says Dr. Sun. “If D-bacteria ever visit us on Earth, they would compete with native bacteria for nutrients,” he adds.
Note : The above story is based on materials provided by Desert Research Institute.
GPS measurements of the displacement vectors. Credit: GFZ
After the strong earthquake that struck Chile on April 2 (CEST), numerous aftershocks, some of them of a considerable magnitude, have struck the region around Iquique. Seismologists from the GFZ German Research Centre for Geosciences doubt that the strong earthquake closed the local seismic gap and decreased the risk of a large earthquake. On the contrary, initial studies of the rupture process and the aftershocks show that only about a third of the vulnerable zone broke.
This vulnerable area is referred to as the seismic gap of Iquique and a strong earthquake is expected to strike here. The Pacific Nazca plate meets the South American plate at South America’s west coast. “In a subsea trench along the coast, the Pacific Ocean floor submerges beneath the continent building up tension that is released in earthquakes,” explains Professor Onno Oncken of the GFZ. “In the course of about 150 years the entire plate boundary from Patagonia in the South to Panama in the North breaks completely with a segmented series of strong earthquakes.” This cycle has been completed except for a last segment west of Iquique in northern Chile. As expected, the strong earthquake of April 2 took place exactly at this seismic gap.
No All-Clear
Initial analyses conducted by GFZ seismologists have shown that there is no sign that tension in the earth’ crust has significantly decreased: “So far tension has been released only in the central section of this vulnerable zone,” Oncken further explains. The series of earthquakes began on March 16 with a 6.7-magnitude earthquake. Although the main earthquake with a magnitude of 8.1 broke the central section of the seismic gap of a length of some 100 kilometres, two large segments further north and south remain intact, and these segments are able to cause strong earthquakes with a high risk of ground shaking and tsunamis.Oncken: “This means that the risk of one or even several earthquakes with a magnitude clearly above 8 still exists.” Furthermore, the location and magnitude of the aftershocks suggest such a scenario.
Since the main quake struck, hundreds of aftershocks have been registered, the strongest that of April 2 (CEST) of a magnitude of 7.6. This earthquake struck about 100 kilometres south of the main earthquake’s epicentre. Together with the its associated aftershocks, it forms a second rupture zone.
Scientists getting ready for a field trip
For such extreme events, the GFZ has a task force called HART (Hazard and Risk Team) that will travel to the area affected to conduct further studies. The assignment aims at gaining a better and more detailed understanding of the rupture process based on the aftershocks, and defining the rupture surface more precisely based on the distribution of the aftershocks. Currently 25 seismometers are being prepared for air transport. Early next week a team of eight GFZ scientists will fly to Chile. The 25 portable seismometers will be used to expand the existing observatory network IPOC (Integrated Plate Boundary Observatory Chile) in order to be able to determine the earthquake epicentres more precisely. In addition highly precise surface displacements will be measured at 50 GPS measuring points. Two new additional continuous GPS stations will be installed to determine how the earthquake has deformed the earth’ crust.The Helmholtz Centre for Ocean Research Geomar in Kiel intends to support the measuring campaign. Ocean floor seismometers will supplement land-based seismic data by providing measurements of the aftershocks on the seafloor.
The Plate Boundary Observatory IPOC in Chile
The GFZ initiated the setup of an observatory directly within the seismic gap in northern Chile in order to be able to precisely measure and capture tectonic processes before, during and after the expected strong earthquake. The observatory called Integrated Plate Boundary Observatory Chile (IPOC) is a European-American network of institutions and scientists. Together with several Chilean and German universities, German, French, Chilean and American non-university research institutions operate a decentralized instrumentation system located at Chile’s convergent plate boundary to gather data on earthquakes, deformations, magmatism, and surface processes.The mission succeeded in the case of the April 2 earthquake: “All our instruments survived the quake and aftershocks unscathed. We now have a set of data that is unique in the world,” says GFZ seismologist Günter Asch with a smile, who was responsible for checking the instruments on site right after the earthquake and who is once again on his way to the region. “We believe that these data will help us understand the entire earthquake process — from the phase that tension builds up to the actual rupture, and also during the post-seismic phase.” This understanding will provide insights into earthquake risks in this part of the world as well as elsewhere.
The IPOC will further expand. To this day more than 20 multi-parameter stations have been set up. They comprise broadband seismographs, accelerometers, continuous GPS receivers, magneto-telluric probes, expansion measuring devices and climate sensors. Their data is transferred to Potsdam in real time. The European Southern Observatory on Cerro Paranal is now also part of the observatory network.
Note : The above story is based on materials provided by Helmholtz Centre Potsdam – GFZ German Research Centre for Geosciences.
Chemical Formula: FeO(OH) Locality: Mesabi district, Minnesota, USA. Name Origin: Named after the German poet, J. W. Goethe (1749-1832).Goethite (FeO(OH)), named after the German polymath and poet Johann Wolfgang von Goethe (1749–1832), an iron bearing hydroxide mineral of the diaspore group, is found in soil and other low-temperature environments. Goethite has been well known since ancient times for its use as a pigment (ochre). Evidence has been found of its use in paint pigment samples taken from the caves of Lascaux in France. It was first described in 1806 for occurrences in the Hollertszug Mine, Dermbach, Herdorf, Siegerland, Rhineland-Palatinate, Germany.In 2003, nanoparticulate authigenic goethite was shown to be the most common diagenetic iron oxyhydroxide in both marine and lake sediments.
To digitally reconstruct the site as it was pre- excavation, scientists scanned 17 photos, developed a model and compared the model to maps drawn by Roland Bird. Credit: CC-BY; Falkingham PL, Bates KT, Farlow JO (2014) Historical Photogrammetry: Bird’s Paluxy River Dinosaur Chase Sequence Digitally Reconstructed as It Was prior to Excavation 70 Years Ago. PLoS ONE 9(4): e93247. doi:10.1371/journal.pone.0093247
Scientists digitally reconstructed a model of a dinosaur chase using photos of theropod and sauropod footprints excavated 70 years ago, according to results published April 2, 2014, in the open access journal PLOS ONE by Peter Falkingham from Royal Veterinary College, London, and colleagues James Farlow and Karl Bates.
As one of the most famous set of dinosaur tracks in the world, the Paluxy River tracks contain both theropod and sauropod footprints. American paleontologist Roland Bird originally excavated the extensive and well preserved footprints in 1940 in Texas, but post-excavation, paleontologists removed the tracks from their original location, divided them into blocks, and transported them to various locations around the world. Prior to their removal, Bird documented the original site with photos and maps, but since excavation portions of the tracks have been lost. A wealth of information could be gained if we were able to view the tracks in one piece again, so researchers set about making that happen.
To digitally reconstruct the site as it was pre- excavation, scientists scanned 17 photos, developed a model and compared the model to maps drawn by Bird. Despite the variation between the photos and the hand drawn maps, scientists were able to reconstruct and view the entire 45 m long sequence in 3D for the first time since excavation. The 3D digital model helped the authors corroborate the maps drawn by Bird when the tracksite was first described. The authors hope that this study will help others digitally recreate paleontological, geological, or archaeological specimens that have been lost or deteriorated over time, but for which old photographic documentation exists.
Peter Falkingham added, “In recent years technology has advanced to the point where highly accurate 3D models can be produced easily and at very little cost just from digital photos, and this has been revolutionizing many different fields. That we can apply that technology to specimens, or even entire sites, that no longer exist but were recorded photographically is extremely exciting.”
Note : The above story is based on materials provided by PLOS.
The April 1, 2014 M8.2 earthquake in northern Chile occurred as the result of thrust faulting at shallow depths near the Chilean coast. The location and mechanism of the earthquake are consistent with slip on the primary plate boundary interface, or megathrust, between the Nazca and South America plates. At the latitude of the earthquake, the Nazca plate subducts eastward beneath the South America plate at a rate of 65 mm/yr. Subduction along the Peru-Chile Trench to the west of Chile has led to uplift of the Andes mountain range and has produced some of the largest earthquakes in the world, including the 2010 M 8.8 Maule earthquake in central Chile, and the largest earthquake on record, the 1960 M 9.5 earthquake in southern Chile. Credit: Image courtesy of U.S. Geological Survey
A magnitude 8.2 earthquake struck off Chile on April 1, 2014 at 23:46:46 UTC, according to the U.S. Geological Survey.
The following is information from the USGS event page on this earthquake.
Tectonic Summary
The April 1, 2014 M8.2 earthquake in northern Chile occurred as the result of thrust faulting at shallow depths near the Chilean coast. The location and mechanism of the earthquake are consistent with slip on the primary plate boundary interface, or megathrust, between the Nazca and South America plates. At the latitude of the earthquake, the Nazca plate subducts eastward beneath the South America plate at a rate of 65 mm/yr. Subduction along the Peru-Chile Trench to the west of Chile has led to uplift of the Andes mountain range and has produced some of the largest earthquakes in the world, including the 2010 M 8.8 Maule earthquake in central Chile, and the largest earthquake on record, the 1960 M 9.5 earthquake in southern Chile.
The April 1 earthquake occurred in a region of historic seismic quiescence — termed the northern Chile or Iquique seismic gap. Historical records indicate a M 8.8 earthquake occurred within the Iquique gap in 1877, which was preceded immediately to the north by an M 8.8 earthquake in 1868.
A recent increase in seismicity rates has occurred in the vicinity of the April 1 earthquake. An M6.7 earthquake with similar faulting mechanism occurred on March 16, 2014 and was followed by 60+ earthquake of M4+, and 26 earthquakes of M5+. The March 16 earthquake was also followed by three M6.2 events on March 17, March 22, and March 23. The spatial distribution of seismicity following the March 16 event migrated spatially to the north through time, starting near 20oS and moving to ~19.5oS. The initial location of the April 1 earthquake places the event near the northern end of this seismic sequence. Other recent large plate boundary ruptures bound the possible rupture area of the April 1 event, including the 2001 M 8.4 Peru earthquake adjacent to the south coast of Peru to the north, and the 2007 M 7.7 Tocopilla, Chile and 1995 M 8.1 Antofagasta, Chile earthquakes to the south. Other nearby events along the plate boundary interface include an M 7.4 in 1967 as well as an M 7.7 in 2005 in the deeper portion of the subduction zone beneath inland Chile.
Seismotectonics of South America (Nazca Plate Region)
The South American arc extends over 7,000 km, from the Chilean margin triple junction offshore of southern Chile to its intersection with the Panama fracture zone, offshore of the southern coast of Panama in Central America. It marks the plate boundary between the subducting Nazca plate and the South America plate, where the oceanic crust and lithosphere of the Nazca plate begin their descent into the mantle beneath South America. The convergence associated with this subduction process is responsible for the uplift of the Andes Mountains, and for the active volcanic chain present along much of this deformation front. Relative to a fixed South America plate, the Nazca plate moves slightly north of eastwards at a rate varying from approximately 80 mm/yr in the south to approximately 65 mm/yr in the north. Although the rate of subduction varies little along the entire arc, there are complex changes in the geologic processes along the subduction zone that dramatically influence volcanic activity, crustal deformation, earthquake generation and occurrence all along the western edge of South America.Most of the large earthquakes in South America are constrained to shallow depths of 0 to 70 km resulting from both crustal and interplate deformation. Crustal earthquakes result from deformation and mountain building in the overriding South America plate and generate earthquakes as deep as approximately 50 km. Interplate earthquakes occur due to slip along the dipping interface between the Nazca and the South American plates. Interplate earthquakes in this region are frequent and often large, and occur between the depths of approximately 10 and 60 km. Since 1900, numerous magnitude 8 or larger earthquakes have occurred on this subduction zone interface that were followed by devastating tsunamis, including the 1960 M9.5 earthquake in southern Chile, the largest instrumentally recorded earthquake in the world. Other notable shallow tsunami-generating earthquakes include the 1906 M8.5 earthquake near Esmeraldas, Ecuador, the 1922 M8.5 earthquake near Coquimbo, Chile, the 2001 M8.4 Arequipa, Peru earthquake, the 2007 M8.0 earthquake near Pisco, Peru, and the 2010 M8.8 Maule, Chile earthquake located just north of the 1960 event.
Large intermediate-depth earthquakes (those occurring between depths of approximately 70 and 300 km) are relatively limited in size and spatial extent in South America, and occur within the Nazca plate as a result of internal deformation within the subducting plate. These earthquakes generally cluster beneath northern Chile and southwestern Bolivia, and to a lesser extent beneath northern Peru and southern Ecuador, with depths between 110 and 130 km. Most of these earthquakes occur adjacent to the bend in the coastline between Peru and Chile. The most recent large intermediate-depth earthquake in this region was the 2005 M7.8 Tarapaca, Chile earthquake.
Earthquakes can also be generated to depths greater than 600 km as a result of continued internal deformation of the subducting Nazca plate. Deep-focus earthquakes in South America are not observed from a depth range of approximately 300 to 500 km. Instead, deep earthquakes in this region occur at depths of 500 to 650 km and are concentrated into two zones: one that runs beneath the Peru-Brazil border and another that extends from central Bolivia to central Argentina. These earthquakes generally do not exhibit large magnitudes. An exception to this was the 1994 Bolivian earthquake in northwestern Bolivia. This M8.2 earthquake occurred at a depth of 631 km, which was until recently the largest deep-focus earthquake instrumentally recorded (superseded in May 2013 by a M8.3 earthquake 610 km beneath the Sea of Okhotsk, Russia), and was felt widely throughout South and North America.
Subduction of the Nazca plate is geometrically complex and impacts the geology and seismicity of the western edge of South America. The intermediate-depth regions of the subducting Nazca plate can be segmented into five sections based on their angle of subduction beneath the South America plate. Three segments are characterized by steeply dipping subduction; the other two by near-horizontal subduction. The Nazca plate beneath northern Ecuador, southern Peru to northern Chile, and southern Chile descend into the mantle at angles of 25° to 30°. In contrast, the slab beneath southern Ecuador to central Peru, and under central Chile, is subducting at a shallow angle of approximately 10° or less. In these regions of “flat-slab” subduction, the Nazca plate moves horizontally for several hundred kilometers before continuing its descent into the mantle, and is shadowed by an extended zone of crustal seismicity in the overlying South America plate. Although the South America plate exhibits a chain of active volcanism resulting from the subduction and partial melting of the Nazca oceanic lithosphere along most of the arc, these regions of inferred shallow subduction correlate with an absence of volcanic activity.
Note : The above story is based on materials provided by U.S. Geological Survey.
Chemical Formula: (Na2,Ca)[Al2Si4O12]·6H2O Locality: Montecchio Maggiore, Vicenza, Italy. Name Origin: Named after the German mineralogist and chemist, Christian Gottlob Gmelin (1792-1860) of Turbingen, Germany. Na modifier added by the zeolite nomenclature committee.
Gmelinite-Na is one of the rarer zeolites but the commonest member of the gmelinite series, gmelinite-Ca, gmelinite-K and gmelinite-Na. It is closely related to the very similar mineral chabazite. Gmelinite was named as a single species in 1825 after Christian Gottlob Gmelin (1792–1860) professor of chemistry and mineralogist from Tübingen, Germany, and in 1997 it was raised to the status of a series.
Gmelinite-Na has been synthesised from Na-bearing aluminosilicate gels. The naturally occurring mineral forms striking crystals, shallow, six sided double pyramids, which can be colorless, white, pale yellow, greenish, orange, pink, and red. They have been compared to an angular flying saucer.
Physical Properties
Cleavage: {1010} Good, {0001} Parting Color: White, Reddish white, Pink, Greenish white, Flesh red. Density: 2.03 – 2.17, Average = 2.09
Diaphaneity: Transparent to translucent Fracture: Brittle – Uneven – Very brittle fracture producing uneven fragments. Hardness: 4.5 – Between Fluorite and Apatite Luster: Vitreous – Dull Streak: white
April-May GSA Today cover image. Credit: Geological Society of America
The repeated cycles of plate tectonics that have led to collision and assembly of large supercontinents and their breakup and formation of new ocean basins have produced continents that are collages of bits and pieces of other continents. Figuring out the origin and make-up of continental crust formed and modified by these tectonic events is a vital to understanding Earth’s geology and is important for many applied fields, such as oil, gas, and gold exploration.
In many cases, the rocks involved in these collision and pull-apart episodes are still buried deep beneath Earth’s surface, so geologists must use geophysical measurements to study these features.
This new study by Elias Parker Jr. of the University of Georgia examines a prominent swath of lower-than-normal magnetism — known as the Brunswick Magnetic Anomaly — that stretches from Alabama through Georgia and off shore to the North Carolina coast.
The cause of this magnetic anomaly has been under some debate. Many geologists attribute the Brunswick Magnetic Anomaly to a belt of 200 million year old volcanic rocks that intruded around the time the Atlantic Ocean. In this case, the location of this magnetic anomaly would then mark the initial location where North America split from the rest of Pangea as that ancient supercontinent broke apart. Parker proposes a different source for this anomalous magnetic zone.
Drawing upon other studies that have demonstrated deeply buried metamorphic rocks can also have a coherent magnetic signal, Parker has analyzed the detailed characteristics of the magnetic anomalies from data collected across zones in Georgia and concludes that the Brunswick Magnetic Anomaly has a similar, deeply buried source. The anomalous magnetic signal is consistent with an older tectonic event — the Alleghanian orogeny that formed the Alleghany-Appalachian Mountains when the supercontinent of Pangea was assembled.
Parker’s main conclusion is that the rocks responsible for the Brunswick Magnetic Anomaly mark a major fault-zone that formed as portions of Africa and North America were sheared together roughly 300 million years ago — and that more extensive evidence for this collision are preserved along this zone. One interesting implication is that perhaps a larger portion of what is now Africa was left behind in the American southeast when Pangea later broke up.
Note : The above story is based on materials provided by Geological Society of America.
An international team of planetary scientists determined that the Moon formed nearly 100 million years after the start of the solar system, according to a paper to be published April 3 in Nature. This conclusion is based on measurements from the interior of Earth combined with computer simulations of the protoplanetary disk from which Earth and other terrestrial planets formed.
The team of researchers from France, Germany and the United States simulated the growth of the terrestrial planets (Mercury, Venus, Earth and Mars) from a disk of thousands of planetary building blocks orbiting the Sun. By analyzing the growth history of Earth-like planets from 259 simulations, the scientists discovered a relationship between the time Earth was impacted by a Mars-sized object to create the Moon and the amount of material added to Earth after that impact.
Augmenting the computer simulation with details on the mass of material added to Earth by accretion after the formation of the Moon revealed a relationship that works much like a clock to date the Moon-forming event. This is the first “geologic clock” in early solar system history that does not rely on measurements and interpretations of the radioactive decay of atomic nuclei to determine age.
“We were excited to find a ‘clock’ for the formation time of the Moon that didn’t rely on radiometric dating methods. This correlation just jumped out of the simulations and held in each set of old simulations we looked at,” says lead author of the Nature article Seth Jacobson of the Observatory de la Cote d’Azur in Nice, France.
Published literature provided the estimate for the mass accreted by Earth after the Moon-forming impact. Other scientists previously demonstrated that the abundance in Earth’s mantle of highly siderophile elements, which are atomic elements that prefer to be chemically associated with iron, is directly proportional to the mass accreted by Earth after the Moon-forming impact.
From these geochemical measurements, the newly established clock dates the Moon to 95 ±32 million years after the beginning of the solar system. This estimate for the Moon-formation agrees with some interpretations of radioactive dating measurements, but not others. Because the new dating method is an independent and direct measurement of the age of the Moon, it helps to guide which radioactive dating measurements are the most useful for this longstanding problem.
“This result is exciting because in the same simulations that can successfully form Mars in only 2 to 5 million years, we can also form the Moon at 100 million years. These vastly different timescales have been very hard to capture in simulations,” says author Dr. Kevin Walsh from the Southwest Research Institute (SwRI) Space Science and Engineering Division.
Note : The above story is based on materials provided by Southwest Research Institute.
Chemical Formula: [Na2][Mg3Al2]Si8O22(OH)2 Locality: Common world wide. Name Origin: From the Greek glaukos – “blue” and fanos – “appearing.”
Glaucophane is the name of a mineral and a mineral group belonging to the sodic amphibole supergroup of the double chain inosilicates, with the chemical formula ☐[Na2][Mg3Al2]Si8O22(OH)2
Glaucophane crystallizes in the monoclinic system.
Characteristics
The blue color is very diagnostic for this species. Glaucophane, along with the closely related mineral riebeckite, to which it forms a series with, and their intermediate crossite, are the only well known amphiboles that are commonly blue. Glaucophane forms a solid solution series with ferroglaucophane; Na2(Fe,Mg)3Al2Si8O22(OH)2. Glaucophane is the magnesium-rich endmember and ferroglaucophane is the iron-rich endmember. Ferroglaucophane is similar to glaucophane but is slightly denser and hence increased specific gravity. The two endmembers are indistinguishable in hand specimens and are strongly pleochroic. Glaucophane’s hardness is 5 – 6 and its specific gravity is approximately 3 – 3.2.
The Permian is a geologic period and system which extends from 298.9 ± 0.2 to 252.2 ± 0.5 (Million years ago). It is the last period of the Paleozoic Era, following the Carboniferous Period and preceding the Triassic Period of the Mesozoic Era. The concept of the Permian was introduced in 1841 by geologist Sir Roderick Murchison, who named it after the ancient kingdom of Permia.
The Permian witnessed the diversification of the early amniotes into the ancestral groups of the mammals, turtles, lepidosaurs and archosaurs. The world at the time was dominated by a single supercontinent known as Pangaea, surrounded by a global ocean called Panthalassa. The extensive rainforests of the Carboniferous had disappeared, leaving behind vast regions of arid desert within the continental interior. Reptiles, who could better cope with these drier conditions, rose to dominance in lieu of their amphibian ancestors. The Permian Period (along with the Paleozoic Era) ended with the largest mass extinction in Earth’s history, in which nearly 90% of marine species and 70% of terrestrial species died out. It would take well into the Triassic for life to recover from this catastrophe.
Discovery
The term “Permian” was introduced into geology in 1841 by Sir R. I. Murchison, president of the Geological Society of London, who identified typical strata in extensive Russian explorations undertaken with Edouard de Verneuil. Murchison asserted in 1841 that he named his “Permian system” after the ancient kingdom of Permia, and not after the then small town of Perm, as usually assumed. The region now lies in the Perm Krai of Russia.
ICS Subdivisions
Official (ICS, 2004) Subdivisions of the Permian System, from most recent to most ancient rock layers are:
Upper Permian (Late Permian) or Lopingian, Tatarian, or Zechstein, epoch [260.4 ± 0.7 Mya – 251.0 ± 0.4 Mya]
Sea levels in the Permian remained generally low, and near-shore environments were limited by the collection of almost all major landmasses into a single continent — Pangaea. This could have in part caused the widespread extinctions of marine species at the end of the period by severely reducing shallow coastal areas preferred by many marine organisms.
During the Permian, all the Earth’s major land masses were collected into a single supercontinent known as Pangaea. Pangaea straddled the equator and extended toward the poles, with a corresponding effect on ocean currents in the single great ocean (“Panthalassa”, the “universal sea”), and the Paleo-Tethys Ocean, a large ocean that was between Asia and Gondwana. The Cimmeria continent rifted away from Gondwana and drifted north to Laurasia, causing the Paleo-Tethys to shrink. A new ocean was growing on its southern end, the Tethys Ocean, an ocean that would dominate much of the Mesozoic Era. Large continental landmasses create climates with extreme variations of heat and cold (“continental climate”) and monsoon conditions with highly seasonal rainfall patterns. Deserts seem to have been widespread on Pangaea. Such dry conditions favored gymnosperms, plants with seeds enclosed in a protective cover, over plants such as ferns that disperse spores. The first modern trees (conifers, ginkgos and cycads) appeared in the Permian.
Three general areas are especially noted for their extensive Permian deposits – the Ural Mountains (where Perm itself is located), China, and the southwest of North America, where the Permian Basin in the U.S. state of Texas is so named because it has one of the thickest deposits of Permian rocks in the world.
Climate
The climate in the Permian was quite varied. At the start of the Permian, the Earth was still at the grip of an Ice Age from the Carboniferous. Glaciers receded around the mid-Permian period as the climate gradually warmed, drying the continent’s interiors. In the late Permian period, the drying continued although the temperature cycled between warm and cool cycles.
Life
Marine biota
Permian marine deposits are rich in fossil mollusks, echinoderms, and brachiopods. Fossilized shells of two kinds of invertebrates are widely used to identify Permian strata and correlate them between sites: fusulinids, a kind of shelled amoeba-like protist that is one of the foraminiferans, and ammonoids, shelled cephalopods that are distant relatives of the modern nautilus. By the close of the Permian, trilobites and a host of other marine groups became extinct.
Terrestrial life in the Permian included diverse plants, fungi, arthropods, and various types of tetrapods. The period saw a massive desert covering the interior of the Pangaea. The warm zone spread in the northern hemisphere, where extensive dry desert appeared. The rocks formed at that time were stained red by iron oxides, the result of intense heating by the sun of a surface devoid of vegetation cover. A number of older types of plants and animals died out or became marginal elements.
The Permian began with the Carboniferous flora still flourishing. About the middle of the Permian a major transition in vegetation began. The swamp-loving lycopod trees of the Carboniferous, such as Lepidodendron and Sigillaria, were progressively replaced in the continental interior by the more advanced seed ferns and early conifers. At the close of the Permian, lycopod and equicete swamps reminiscent of Carboniferous flora were relegated to a series of equatorial islands in the Paleotethys Sea that later would become South China.
The Permian saw the radiation of many important conifer groups, including the ancestors of many present-day families. Rich forests were present in many areas, with a diverse mix of plant groups. The southern continent saw extensive seed fern forests of the Glossopteris flora. Oxygen levels were probably high there. The ginkgos and cycads also appeared during this period.
Insects
By the Pennsylvanian and well into the Permian, by far the most successful were primitive relatives of cockroaches. Six fast legs, four well developed folding wings, fairly good eyes, long, well developed antennae (olfactory), an omnivorous digestive system, a receptacle for storing sperm, a chitin-based exoskeleton that could support and protect, as well as a form of gizzard and efficient mouth parts, gave it formidable advantages over other herbivorous animals. About 90% of insects at the start of the Permian were cockroach-like insects (“Blattopterans”).
Primitive forms of dragonflies (Odonata) were the dominant aerial predators and probably dominated terrestrial insect predation as well. True Odonata appeared in the Permian and all are effectively semi-aquatic insects (aquatic immature stages, and terrestrial adults), as are all modern odonates. Their prototypes are the oldest winged fossils, go back to the Devonian, and are different in several respects from the wings of other insects. Fossils suggest they may have possessed many modern attributes even by the late Carboniferous, and it is possible that they captured small vertebrates, for at least one species had a wing span of 71 centimetres (28 in). Several other insect groups appeared during the Permian, including the Coleoptera (beetles) and Hemiptera (true bugs).
Synapsid and amphibian fauna
Early Permian terrestrial faunas were dominated by pelycosaurs, diadectes and amphibians, the middle Permian by primitive therapsids such as the dinocephalia, and the late Permian by more advanced therapsids such as gorgonopsians and dicynodonts. Towards the very end of the Permian the first archosaurs appeared, a group that would give rise to the crurotarsans and the dinosaurs in the following period. Also appearing at the end of the Permian were the first cynodonts, which would go on to evolve into mammals during the Triassic. Another group of therapsids, the therocephalians (such as Lycosuchus), arose in the Middle Permian. There were no aerial vertebrates (with the exception of gliding lizards, the avicephalans).
The Permian period saw the development of a fully terrestrial fauna and the appearance of the first large herbivores and carnivores. It was the high tide of the anapsids in the form of the massive Pareiasaurs and host of smaller, generally lizard-like groups. A group of small reptiles, the diapsids started to abound. These were the ancestors to most modern reptiles and the ruling dinosaurs as well as pterosaurs and crocodiles.
Thriving also, were the early ancestors to mammals, the synapsida, which included some large members such as Dimetrodon. Reptiles grew to dominance among vertebrates, because their special adaptations enabled them to flourish in the drier climate.
Permian amphibians consisted of temnospondyli, lepospondyli and batrachosaurs.
The Permian ended with the most extensive extinction event recorded in paleontology: the Permian-Triassic extinction event. 90% to 95% of marine species became extinct, as well as 70% of all land organisms. It is also the only known mass extinction of insects. Recovery from the Permian-Triassic extinction event was protracted; on land, ecosystems took 30M years to recover. Trilobites, which had thrived since Cambrian times, finally became extinct before the end of the Permian. Nautiluses, a species of cephalopods, surprisingly survived this occurrence.
There is also significant evidence that massive flood basalt eruptions from magma output lasting thousands of years in what is now the Siberian Traps contributed to environmental stress leading to mass extinction. The reduced coastal habitat and highly increased aridity probably also contributed. Based on the amount of lava estimated to have been produced during this period, the worst-case scenario is an expulsion of enough carbon dioxide from the eruptions to raise world temperatures five degrees Celsius.
Another hypothesis involves ocean venting of hydrogen sulfide gas. Portions of deep ocean will periodically lose all of their dissolved oxygen allowing bacteria that live without oxygen to flourish and produce hydrogen sulfide gas. If enough hydrogen sulfide accumulates in an anoxic zone, the gas can rise into the atmosphere. Oxidizing gases in the atmosphere would destroy the toxic gas, but the hydrogen sulfide would soon consume all of the atmospheric gas available to change it. Hydrogen sulfide levels would increase dramatically over a few hundred years. Modeling of such an event indicates that the gas would destroy ozone in the upper atmosphere allowing ultraviolet radiation to kill off species that had survived the toxic gas.[29] Of course, there are species that can metabolize hydrogen sulfide.
Another hypothesis builds on the flood basalt eruption theory. Five degrees Celsius would not be enough increase in world temperatures to explain the death of 95% of life. But such warming could slowly raise ocean temperatures until frozen methane reservoirs below the ocean floor near coastlines melted, expelling enough methane, among the most potent greenhouse gases, into the atmosphere to raise world temperatures an additional five degrees Celsius. The frozen methane hypothesis helps explain the increase in carbon-12 levels midway into the Permian-Triassic boundary layer. It also helps explain why the first phase of the layer’s extinctions was land-based, the second was marine-based (and starting right after the increase in C-12 levels), and the third land-based again.
An even more speculative hypothesis is that intense radiation from a nearby supernova was responsible for the extinctions.
In 2006, a group of American scientists from The Ohio State University reported evidence for a possible huge meteorite crater (Wilkes Land crater) with a diameter of around 500 kilometers in Antarctica. The crater is located at a depth of 1.6 kilometers beneath the ice of Wilkes Land in eastern Antarctica. The scientists speculate that this impact may have caused the Permian–Triassic extinction event, although its age is bracketed only between 100 million and 500 million years ago. They also speculate that it may have contributed in some way to the separation of Australia from the Antarctic landmass, which were both part of a supercontinent called Gondwana. Levels of iridium and quartz fracturing in the Permian-Triassic layer do not approach those of the Cretaceous–Paleogene boundary layer. Given that a far greater proportion of species and individual organisms became extinct during the former, doubt is cast on the significance of a meteor impact in creating the latter. Further doubt has been cast on this theory based on fossils in Greenland showing the extinction to have been gradual, lasting about eighty thousand years, with three distinct phases.
Many scientists argue that the Permian-Triassic extinction event was caused by a combination of some or all of the hypotheses above and other factors; the formation of Pangaea decreased the number of coastal habitats and may have contributed to the extinction of many clades.
Note : The above story is based on materials provided by Wikipedia
Map of the Rio de la Plata Basin showing the Paraná River and its major tributaries
The Paraná River is a river in south Central South America, running through Brazil, Paraguay and Argentina for some 4,880 kilometres (3,030 mi). It is second in length only to the Amazon River among South American rivers. The name Paraná is an abbreviation of the phrase “para rehe onáva”, which comes from the Tupi language and means “like the sea” (that is, “as big as the sea”). It merges first with the Paraguay River and then farther downstream with the Uruguay River to form the Río de la Plata and empties into the Atlantic Ocean.
Course
The course is formed at the confluence of the Paranaiba and Grande rivers in southern Brazil. From the confluence the river flows in a generally southwestern direction for about 619 km (385 mi) before encountering the city of Saltos del Guaira, Paraguay. This was once the location of the Sete Quedas waterfall, where the Paraná fell over a series of seven cascades. This natural feature was said to rival the world famous Iguazu Falls to the south. The falls were flooded, however, by the construction of the Itaipu dam, which began operating in 1984.
For approximately the next 200 km (120 mi) the Paraná flows southward and forms a natural boundary between Paraguay and Brazil until the confluence with the Iguazu River. Shortly upstream from this confluence, however, the river is dammed by the Itaipu Dam, the second largest hydroelectric power station in the world (after the Three Gorges Dam in the People’s Republic of China), and creating a massive, shallow reservoir behind it.
After merging with the Iguazu, the Paraná then becomes the natural border between Paraguay and Argentina. Overlooking the Paraná River from Encarnación, Paraguay, across the river, is downtown Posadas, Argentina. The river continues its general southward course for about 468 km (291 mi) before making a gradual turn to the west for another 820 km (510 mi), and then encounters the Paraguay River, the largest tributary along the course of the river. Before this confluence the river passes through a second major hydroelectric project, the Yaciretá dam, a joint project between Paraguay and Argentina. The massive reservoir formed by the project has been the source of a number of problems for people living along the river, most notably the poorer merchants and residents in the low lying areas of Encarnación, a major city on the southern border of Paraguay. River levels rose dramatically upon completion of the dam, flooding out large sections of the city’s lower areas.
From the confluence with the Paraguay River, the Paraná again turns to the south for another approximately 820 km (510 mi) through Argentina, making a slow turn back to the east near the city of Rosario for the final stretch of less than 500 km (310 mi) before merging with the Uruguay River to form the Río de la Plata and emptying into the Atlantic Ocean. During the part of its course downstream from the city of Diamante, Entre Ríos, it splits into several arms and forms the Paraná Delta, a long flood plain which reaches up to 60 km in width.
Note : The above story is based on materials provided by Wikipedia
Chemical Formula: (Co,Fe)AsS Locality: In Sweden, at Hakansbo, Vastmanland, as large twinned and untwinned crystals. Name Origin: From the Greek for “blue,” in reference to its use in the dark blue glass called smalt.
Glaucodot is a cobalt iron arsenic sulfide mineral with formula: (Co,Fe)AsS. The cobalt:iron(II) ratio is typically 3:1 with minor nickel substituting. It forms a series with arsenopyrite (FeAsS). It is an opaque grey to tin-white typically found as massive forms without external crystal form. It crystallizes in the orthorhombic system. The locality at Håkansboda, Sweden has rare twinned dipyramidal crystals . It is brittle with a Mohs hardness of 5 and a specific gravity of 5.95. It occurs in high temperature hydrothermal deposits with pyrrhotite and chalcopyrite. Glaucodot is classed as a sulfide in the arsenopyrite löllingite group.
Glaucodot was first described in 1849 in Huasco, Valparaíso Province, Chile. Its name originates from the Greek γλανκός (“blue”) in reference to its use in the dark blue glass called smalt.
One of the fossil feeding appendages of Tamisiocaris. Credit: Dr Jakob Vinther, University of Bristol
Ancient, giant marine animals used bizarre facial appendages to filter food from the ocean, according to new fossils discovered in northern Greenland. The new study, led by the University of Bristol and published today in Nature, describes how the strange species, called Tamisiocaris, used these huge, specialized appendages to filter plankton, similar to the way modern blue whales feed today.
The animals lived 520 million years ago during the Early Cambrian, a period known as the ‘Cambrian Explosion’ in which all the major animal groups and complex ecosystems suddenly appeared. Tamisiocaris belongs to a group of animals called anomalocarids, a type of early arthropod that included the largest and some of the most iconic animals of the Cambrian period. They swam using flaps down either side of the body and had large appendages in front of their mouths that they most likely used to capture larger prey, such as trilobites.
However, the newly discovered fossils show that those predators also evolved into suspension feeders, their grasping appendages morphing into a filtering apparatus that could be swept like a net through the water, trapping small crustaceans and other organisms as small as half a millimetre in size.
The evolutionary trend that led from large, apex predators to gentle, suspension-feeding giants during the highly productive Cambrian period is one that has also taken place several other times throughout Earth’s history, according to lead author Dr Jakob Vinther, a lecturer in macroevolution at the University of Bristol.
Dr Vinther said: “These primitive arthropods were, ecologically speaking, the sharks and whales of the Cambrian era. In both sharks and whales, some species evolved into suspension feeders and became gigantic, slow-moving animals that in turn fed on the smallest animals in the water.”
In order to fully understand how the Tamisiocaris might have fed, the researchers created a 3D computer animation of the feeding appendage to explore the range of movements it could have made.
“Tamisiocaris would have been a sweep net feeder, collecting particles in the fine mesh formed when it curled its appendage up against its mouth,” said Dr Martin Stein of the University of Copenhagen, who created the computer animation. “This is a rare instance when you can actually say something concrete about the feeding ecology of these types of ancient creatures with some confidence.”
The discovery also helps highlight just how productive the Cambrian period was, showing how vastly different species of anomalocaridids evolved at that time, and provides further insight into the ecosystems that existed hundreds of millions of years ago.
“The fact that large, free-swimming suspension feeders roamed the oceans tells us a lot about the ecosystem,” Dr Vinther said. “Feeding on the smallest particles by filtering them out of the water while actively swimming around requires a lot of energy — and therefore lots of food.”
Tamisiocaris is one of many recent discoveries of remarkably diverse anomalocarids found in rocks aged 520 to 480 million years old. “We once thought that anomalocarids were a weird, failed experiment,” said co-author Dr Nicholas Longrich at the University of Bath. “Now we’re finding that they pulled off a major evolutionary explosion, doing everything from acting as top predators to feeding on tiny plankton.”
The Tamisiocaris fossils were discovered during a series of recent expeditions led by co-author David Harper, a professor at Durham University. “The expeditions have unearthed a real treasure trove of new fossils in one of the remotest parts of the planet, and there are many new fossil animals still waiting to be described,” he said. “Our new understanding of this remarkable animal adds another piece to a fascinating jigsaw puzzle.”
The expeditions were funded by the Agouron Institute, Carlsberg Foundation and Geocenter Denmark.
Note : The above story is based on materials provided by University of Bristol.
