WFS

Formation of sedimentary layers of white clay, Tamilnadu, India

Fossil site for wood fossils, Tamilnadu, India

Fossil site in Kerala, India

Fossil wood park maintained by geological survey of India at Tamilnadu

Cretaceous fossil sites india

Fossils in rack:-Cyad

Fossils in rack:-echiniderms

Fossils in rack:-Rastellum sp

Pre-historic seabed, Cretaceous period

Bird brains predate birds themselves

August 4th, 2013

Riffin

New research provides evidence that dinosaurs evolved the brainpower necessary for flight well before they actually took to the air as birds. Based on high-resolution X-ray computed tomographic (CT) scans, the study, published today in Nature, takes a comprehensive look at the so-called “bird brain.” Contrary to the cliché, the term describes a relatively enlarged brain that has the capacity required for flight and was present in one of the earliest known birds, Archaeopteryx. In the new study, scientists reveal that at least a few non-avian dinosaurs had brains that were as large or larger than that of Archaeopteryx, indicating that some dinosaurs already suspected of possessing flight capability would have had the neurological hardwiring necessary for this behavior.

This CT scan shows the transparent skull and opaque brain cast of Zanabazar junior, a troodontid dinosaur. The endocast is partitioned into the following neuroanatomical regions: brain stem (yellow), cerebellum (blue), optic lobes (red), cerebrum (green), and olfactory bulbs (orange). – ©AMNH/A. Balanoff

“Archaeopteryx has always been set up as a uniquely transitional species between feathered dinosaurs and modern birds, a halfway point,” said lead author Amy Balanoff, a research associate at the American Museum of Natural History and a postdoctoral researcher at Stony Brook University. “But by studying the cranial volume of closely related dinosaurs, we learned that Archaeopteryx might not have been so special.”

Birds can be distinguished from other living reptiles by their brains, which are enlarged compared to body size. This “hyperinflation,” most obvious in the forebrain, is important for providing the superior vision and coordination required to fly. But scientists are increasingly finding that features once considered exclusive to modern birds, such as feathers and the presence of wishbones, are now known to have first appeared in non-avian dinosaurs. The new study provides more evidence to add the hyperinflated brain to that list.

The researchers used CT scanners at the University of Texas, Ohio University, Stony Brook University, and the Museum to peer inside the braincases of more than two dozen specimens, including modern birds, Archaeopteryx, and closely related non-avian dinosaurs like tyrannosaurs. By stitching together the CT scans, the scientists created 3-D reconstructions of the skulls’ interiors. In addition to calculating the total volume of each digital brain cast, the research team also determined the size of each brain’s major anatomical regions, including the olfactory bulbs, cerebrum, optic lobes, cerebellum, and brain stem.

“The story of brain size is more than its relationship to body size,” said coauthor Gabriel Bever, an assistant professor of anatomy at the New York Institute of Technology. “If we also consider how the different regions of the brain changed relative to each other, we can gain insight into what factors drove brain evolution as well as what developmental mechanisms facilitated those changes.”

The researchers found that in terms of volumetric measurements, Archaeopteryx is not in a unique transitional position between non-avian dinosaurs and modern birds. Several other non-avian dinosaurs sampled, including bird-like oviraptorosaurs and troodontids, actually had larger brains relative to body size than Archaeopteryx.

“If Archaeopteryx had a flight-ready brain, which is almost certainly the case given its morphology, then so did at least some other non-avian dinosaurs,” Balanoff said.

The researchers also examined another factor that is important to flight in modern birds: a neurological structure called the wulst, which is used in information processing and motor control. The team identified an indentation in the digital brain cast of Archaeopteryx that might be homologous to the wulst seen in living birds. But this indentation is not found in non-avian dinosaurs that have bigger brains than Archaeopteryx, presenting the research team with a new question to explore in the future.

Click on this image to view the .mp4 video

This video shows the three-dimensional scan of an albatross ([I]Phoebastria immutabilis[/I]) skull and brain endocast (shown in blue) taken with high-resolution X-ray computed tomography. The specimen is one of more than two dozen skulls of modern birds, early extinct birds, and closely related dinosaurs scanned for a recent study on ‘bird brains’ led by the American Museum of Natural History. – ©AMNH/A. Balanoff

A Waterworld of Volcanoes

August 3rd, 2013

Riffin

At Loki’s Castle in the Arctic Ocean, researchers from the University of Bergen (UiB) have discovered a so far unknown world of volcanic activity underwater. They hope that this can become Norway’s new national park.

In 2008, UiB researchers discovered Loki’s Castle, a field of five active hydrothermal vents on the Mid-Atlantic Ridge between Norway and Greenland at 73°N. The field contains rich metal deposits and a unique wildlife.

UiB researchers have found 20 new animal species in the volcano areas that they discovered this summer. These animals live off the heat caused by the hydrothermal vents in the area. (Credit: University of Bergen)

New discoveries

This summer a team led by the director of UiB’s Centre for Geobiology, Professor Rolf Birger Pedersen, discovered five new hydrothermal vents in Loki’s Castle. The vents were discovered at depths ranging from 100 to 2,500 metres. In this area, which is the most geological active part of Norway, a new volcanic seabed is formed at a rate of two centimetres a year.

On Thursday 1 August, Professor Pedersen and UiB’s Rector Dag Rune Olsen met with Norway’s Minister of the Environment, Bård Vegar Solhjell, to talk about the research on the world’s last few blank spots and to discuss how Norway can contribute to preserving these wildlife reserves.

“These discoveries are incredibly interesting as they represent a part of the Norwegian nature that is under-explored. They represent a part of nature where conditions are extreme and where we expect to find a lot of new and exciting biology,” Rector Olsen said.

Unique videos

At the meeting Olsen and Pedersen showed new and unique video recordings of Norway’s unknown volcanoes to the minister and other select guests. Minister Solhjell was impressed with the research done and promised action.

“At the Ministry of the Environment will start work to consider more carefully how to take care of these areas in the best way possible. It is an amazing idea that we can create spectacular underwater nature parks, but it may not happen right away as we need more knowledge in how to make this work,” Solhjell said.

Norway is a volcanic country on par with Iceland. The difference being that whereas Iceland’s volcanoes are onshore, Norway’s volcano landscape is in the deep sea. Norway’s volcanoes are lined up underwater in large active earthquake zones, and there are hydrothermal vents churning out hot water — at 320 degrees Celsius — which gives rise to unique ecosystems and metal deposits on the seabed.

UiB’s Centre for Geobiology is Norway’s leading deep-ocean research environment. For the past ten years, researchers and students from the centre have explored this volcanic underwater world. Through their summer expeditions to the area, they have discovered new Norwegian nature every year.

In this period they have surveyed hundreds of undersea volcanoes and a number of hydrothermal vents. Loki’s Castle (Lokeslottet), Soria Moria and Trollveggen are the names given to the hydrothermal vents discovered by the UiB researchers in 2005 and 2008.

National park on the seabed

The researchers believe that Loki’s Castle could become a Norwegian national park on the seabed, not unlike Yellowstone in the United States or Iceland’s geysers.

The UiB researchers see that there could be future conflicts of interest if such a national park is to be established. They have found significant metal deposits that are formed around the hydrothermal vents in Loki’s Castle. The material value of these deposits remains unknown, but the mining industry is already showing a growing interest in exploiting these resources on the seabed. Deep-ocean mining could become a reality in the not too distant future. The distinctive wildlife in the deep seas, with the hydrothermal vents as oases of a unique genetic life, means that any industrial activity must be weighed against environmental concerns.

Based on their knowledge, the UiB researchers are thus proposing that deep-marine nature parks should be established as soon as possible. This is of particular importance for Norway, with vast deep-sea areas to manage. This management must be based on scientific knowledge.

“It is our opinion that this area is so unique that it should be preserved. We are talking about very vulnerable environments,” Professor Pedersen said and pointed out that research also needs to create more knowledge about the wildlife in the area.

“It would represent a new way of preservation thinking if a national park was to be linked to Loki’s Castle,” Rector Olsen said. “Given the University of Bergen’s marine research profile, we definitely want to take responsibility for further exploration of these fields so as to give the Norwegian government a good scientific basis when they make a decision.”

Ancient Jigsaw Puzzle of Past Supercontinent Revealed

July 30th, 2013

Riffin

A new study published today in the journal Gondwana Research, has revealed the past position of the Australian, Antarctic and Indian tectonic plates, demonstrating how they formed the supercontinent Gondwana 165 million years ago.

Researchers from Royal Holloway University, The Australian National University and Geoscience Australia, have helped clear up previous uncertainties on how the plates evolved and where they should be positioned when drawing up a picture of the past.

Image from video. The coloured polygons represent different geological units that have been mapped (and inferred) by geologists over many years. These geological units formed before the continents broke apart, so we can use their position to put the “jigsaw pieces” back together again. Many other reconstructions do not use the geological boundaries to match the continental “jigsaw pieces” back together – so they don’t align properly. (Credit: Image courtesy of University of Royal Holloway London)

Dr Lloyd White from the Department of Earth Sciences at Royal Holloway University said: “The Earth’s tectonic plates move around through time. As these movements occur over many millions of years, it has previously been difficult to produce accurate maps of where the continents were in the past.

“We used a computer program to move geological maps of Australia, India and Antarctica back through time and built a ‘jigsaw puzzle’ of the supercontinent Gondwana. During the process, we found that many existing studies had positioned the plates in the wrong place because the geological units did not align on each plate.”

The researchers adopted an old technique used by people who discovered the theories of continental drift and plate tectonics, but which had largely been ignored by many modern scientists.

“It was a simple technique, matching the geological boundaries on each plate. The geological units formed before the continents broke apart, so we used their position to put this ancient jigsaw puzzle back together again,” Dr White added.

“It is important that we know where the plates existed many millions of years ago, and how they broke apart, as the regions where plates break are often where we find major oil and gas deposits, such as those that are found along Australia’s southern margin.”

A video demonstrating the ancient jigsaw puzzle can be viewed here: http://vimeo.com/68311221

New Evidence for Warm-Blooded Dinosaurs

July 29th, 2013

Riffin

University of Adelaide research has shown new evidence that dinosaurs were warm-blooded like birds and mammals, not cold-blooded like reptiles as commonly believed.

In a paper published in PLoS ONE, Professor Roger Seymour of the University’s School of Earth and Environmental Sciences, argues that cold-blooded dinosaurs would not have had the required muscular power to prey on other animals and dominate over mammals as they did throughout the Mesozoic period.

“Much can be learned about dinosaurs from fossils but the question of whether dinosaurs were warm-blooded or cold-blooded is still hotly debated among scientists,” says Professor Seymour.

“Some point out that a large saltwater crocodile can achieve a body temperature above 30°C by basking in the sun, and it can maintain the high temperature overnight simply by being large and slow to change temperature.

“They say that large, cold-blooded dinosaurs could have done the same and enjoyed a warm body temperature without the need to generate the heat in their own cells through burning food energy like warm-blooded animals.”

In his paper, Professor Seymour asks how much muscular power could be produced by a crocodile-like dinosaur compared to a mammal-like dinosaur of the same size.

T. rex (artist’s rendering). (Credit: © DX / Fotolia)

Saltwater crocodiles reach over a tonne in weight and, being about 50% muscle, have a reputation for being extremely powerful animals.

But drawing from blood and muscle lactate measurements collected by his collaborators at Monash University, University of California and Wildlife Management International in the Northern Territory, Professor Seymour shows that a 200 kg crocodile can produce only about 14% of the muscular power of a mammal at peak exercise, and this fraction seems to decrease at larger body sizes.

“The results further show that cold-blooded crocodiles lack not only the absolute power for exercise, but also the endurance, that are evident in warm-blooded mammals,” says Professor Seymour.

“So, despite the impression that saltwater crocodiles are extremely powerful animals, a crocodile-like dinosaur could not compete well against a mammal-like dinosaur of the same size.

“Dinosaurs dominated over mammals in terrestrial ecosystems throughout the Mesozoic. To do that they must have had more muscular power and greater endurance than a crocodile-like physiology would have allowed.”

His latest evidence adds to that of earlier work he did on blood flow to leg bones which concluded that the dinosaurs were possibly even more active than mammals.

Fossil Shows Fish Had Sucker On Its Back

July 28th, 2013

Riffin

A 30 million year-old fossil has revealed how remoras — also called sharksuckers — evolved the sucker that enables them to stick to other fishes and ‘hitch a ride’.

Previous evidence, such as the segmented structure of the sucker and how it develops in a similar way to fins in normal fish, led scientists to believe that it must be a modified dorsal fin — the fin located on the back of normal fishes. But the evolutionary steps that led from fin to sucker were a mystery.

Now a team led by scientists from Oxford University and London’s Natural History Museum has studied an early fossil remora and found that it evolved a fully-functioning sucker — ‘adhesion disc’ — on its back. It was only later in the evolutionary history of remoras that the sucker migrated to the top of the head where it is found in all remoras alive today.

A report of the research is published in the journal Proceedings of the Royal Society B.

‘The remora sucker is a truly amazing anatomical specialisation but, strange as it may seem, it evolved from a spiny fin,’ said Dr Matt Friedman of Oxford University’s Department of Earth Sciences, lead author of the report. ‘In this fossil the fin is clearly modified as a disc but is found on the back of the fish. It enables us to say that first fin spines on the back broadened to form wide segments of a suction disc. After the disc evolved, it migrated to the skull, and it was there that individual segments became divided in two, the number of segments increased, and a row of spines were developed on the back of individual segments.’

Remora fossil body. The sucker is boxed off in white. (Credit: Image courtesy of University of Oxford)

Modern remoras use their sucker to fasten themselves to hosts including whales, turtles, and sharks. The researchers have shown that the fossil remora (†Opisthomyzon), dating from the Oligocene period and unearthed in Switzerland, falls outside the branch on the evolutionary tree occupied by all living remoras. As such it preserves primitive aspects of the shape and construction of the adhesion disc not found in modern remoras, all of which share discs that are broadly similar in construction.

‘It’s exciting that fossil fish from the Natural History Museum were so crucial to this study, and shows the important value of our collections for scientific research,’ said Dr Zerina Johanson, palaeontologist at London’s Natural History Museum. ‘Following painstaking preparation by our fossil preparator, Mark Graham, we were able to clearly see several important features of the disc in the fossil, for example that it’s much shorter than the disc in living remoras, with fewer segments.’

‘One of the remarkable things we’ve learned about modern fishes is that some creatures that look very different, for example pufferfishes and anglerfishes, are actually very closely related,’ said Dr Friedman. ‘It’s through fossils like this one, which preserve body plans and structures that have been pruned from the evolutionary tree by extinction, that we can unravel how they diverged from one another to assume the very different forms we see today.’

Devastating Long-Distance Impact of Earthquakes

July 25th, 2013

Riffin

In 2006 the island of Java, Indonesia was struck by a devastating earthquake followed by the onset of a mud eruption to the east, flooding villages over several square kilometers and that continues to erupt today. Until now, researchers believed the earthquake was too far from the mud volcano to trigger the eruption. Geophysicists at the University of Bonn, Germany and ETH Zurich, Switzerland use computer-based simulations to show that such triggering is possible over long distances. The results have been published in Nature Geoscience.

On May 27, 2006 the ground of the Indonesian island Java was shaking with a magnitude 6.3 earthquake. The epicenter was located 25 km southwest of the city of Yogyakarta and initiated at a depth of 12 km. The earthquake took thousands of lives, injured ten thousand and destroyed buildings and homes. 47 hours later, about 250 km from the earthquake hypocenter, a mud volcano formed that came to be known as “Lusi,” short for “Lumpur Sidoarjo.” Hot mud erupted in the vicinity of an oil drilling-well, shooting mud up to 50 m into the sky and flooding the area. Scientists expect the mud volcano to be active for many more years.

Eruption of mud volcano has natural cause

Was the eruption of the mud triggered by natural events or was it human-made by the nearby exploration-well? Geophysicists at the University of Bonn, Germany and at ETH Zürich, Switzerland investigated this question with numerical wave-propagation experiments. “Many researchers believed that the earthquake epicenter was too far from Lusi to have activated the mud volcano,” says Prof. Dr. Stephen A. Miller from the department of Geodynamics at the University of Bonn. However, using their computer simulations that include the geological features of the Lusi subsurface, the team of Stephen Miller concluded that the earthquake was the trigger, despite the long distance.

The overpressured solid mud layer was trapped between layers with different acoustic properties, and this system was shaken from the earthquake and aftershocks like a bottle of champagne. The key, however, is the reflections provided by the dome-shaped geology underneath Lusi that focused the seismic waves of the earthquakes like the echo inside a cave. Prof. Stephen Miller explains: “Our simulations show that the dome-shaped structure with different properties focused seismic energy into the mud layer and could very well have liquified the mud that then injected into nearby faults.”

Previous studies would have underestimated the energy of the seismic waves, as ground motion was only considered at the surface. However, geophysicists at the University of Bonn suspect that those were much less intense than at depth. The dome-like structure “kept” the seismic waves at depth and damped those that reached the surface. “This was actually a lower estimate of the focussing effect because only one wave cycle was input. This effect increases with each wave cycle because of the reducing acoustic impedance of the pressurizing mud layer.” In response to claims that the reported highest velocity layer used in the modeling is a measurement artifact, Miller says „that does not change our conclusions because this effect will occur whenever a layer of low acoustic impedance is sandwiched between high impedance layers, irrespective of the exact values of the impedances. And the source of the Lusi mud was the inside of the sandwich. ”

Seismograph. (Credit: © huebi71 / Fotolia)

It has already been proposed that a tectonic fault is connecting Lusi to a 15 km distant volcanic system. Prof. Miller explains “This connection probably supplies the mud volcano with heat and fluids that keep Lusi erupting actively up to today,” explains Miller.

With their publication, scientists from Bonn and Zürich point out, that earthquakes can trigger processes over long distances, and this focusing effect may apply to other hydrothermal and volcanic systems. Stephen Miller concludes: “Being a geological rarity, the mud volcano may contribute to a better understanding of triggering processes and relationships between seismic and volcanic activity.” Miller also adds „maybe this work will settle the long-standing controversy and focus instead on helping those affected.” The island of Java is part of the so called Pacific Ring of Fire, a volcanic belt which surrounds the entire Pacific Ocean. Here, oceanic crust is subducted underneath oceanic and continental tectonic plates, leading to melting of crustal material at depth. The resulting magma uprises and is feeding numerous volcanoes.

Parent Dinosaurs Shared the Work

July 24th, 2013

Riffin

A study into the brooding behaviour of birds has revealed their dinosaur ancestors shared the load when it came to incubation of eggs.

Research into the incubation behaviour of birds suggests the type of parental care carried out by their long extinct ancestors.

The study aimed to test the hypothesis that data from extant birds could be used to predict the incubation behaviour of Theropods, the group of carnivorous dinosaurs from which birds descended.

The paper, out today in Biology Letters, was co-authored by Dr Charles Deeming and Dr Marcello Ruta from the University of Lincoln’s School of Life Sciences and Dr Geoff Birchard from George Mason University, Virginia.

Oviraptorid skeleton and eggs in the Senckenberg Museum in Frankfurt am Main. (Credit: EvaK via Wikimedia Commons, Creative Commons license)

By taking into account factors known to affect egg and clutch size in living bird species, the authors — who started their investigation last summer at the University of Lincoln’s Riseholme campus — found that shared incubation was the ancestral incubation behaviour. Previously it had been claimed that only male Theropod dinosaurs incubated the eggs.

Dr Deeming said: “In 2009 a study in the journal Science suggested that it was males of the small carnivorous dinosaurs Troodon and Oviraptor that incubated their eggs. Irrespective of whether you accept the idea of Theropod dinosaurs sitting on eggs like birds or not, the analysis raised some concerns that we wanted to address. We decided to repeat the study with a larger data set and a better understanding of bird biology because other palaeontologists were starting to use the original results in Science in order to predict the incubation behaviour of other dinosaur species. Our analysis of the relationship between female body mass and clutch mass was interesting in its own right but also showed that it was not possible to conclude anything about incubation in extinct distant relatives of the birds.”

Palaeobiologist Dr Ruta was involved in mapping the parental behaviour in modern birds on to an evolutionary tree.

Dr Ruta said: “As always in any study involving fossils, knowledge of extant organisms helps us make inferences about fossils. Fossils have a unique role in shaping our knowledge of the Tree of Life and the dynamics of evolutionary processes. However, as is the case with our study, data from living organisms may augment and refine the potential of fossil studies and may shift existing notions of the biology and behaviour of long extinct creatures.”

Dr Birchard added: “The previous study was carried out to infer the type of parental care in dinosaurs that are closely related to birds. That study proposed that paternal care was present in these dinosaurs and this form of care was the ancestral condition for birds. Our new analysis based on three times as many species as in the previous study indicates that parental care cannot be inferred from simple analyses of the relationship of body size to shape, anatomy, physiologyand behaviour. Such analyses ought to take into account factors such as shared evolutionary history and maturity at hatching. However, our data does suggest that the dinosaurs used in the previous study were likely to be quite mature at birth.”

The project has helped in understanding the factors affecting the evolution of incubation in birds. More importantly it is hoped that the new analysis will assist palaeontologists in their interpretation of future finds of dinosaur reproduction in the fossil record.

Greening of the Earth Pushed Way Back in Time

July 23rd, 2013

Riffin

Conventional scientific wisdom has it that plants and other creatures have only lived on land for about 500 million years, and that landscapes of the early Earth were as barren as Mars.

A new study, led by geologist Gregory J. Retallack of the University of Oregon, now has presented evidence for life on land that is four times as old — at 2.2 billion years ago and almost half way back to the inception of the planet.

This is an interpretive view of Diskagma buttonii with exterior view, left, and cross section. The fossils are the size of match heads and were found connected into bunches by threads in the surface of an ancient soil from South Africa. (Credit: Courtesy of Gregory Retallack)

That evidence, which is detailed in the September issue of the journal Precambrian Research, involves fossils the size of match heads and connected into bunches by threads in the surface of an ancient soil from South Africa. They have been named Diskagma buttonii, meaning “disc-shaped fragments of Andy Button,” but it is unsure what the fossils were, the authors say.

“They certainly were not plants or animals, but something rather more simple,” said Retallack, professor of geological sciences and co-director of paleontological collections at the UO’s Museum of Natural and Cultural History. The fossils, he added, most resemble modern soil organisms called Geosiphon, a fungus with a central cavity filled with symbiotic cyanobacteria.

“There is independent evidence for cyanobacteria, but not fungi, of the same geological age, and these new fossils set a new and earlier benchmark for the greening of the land,” he said. “This gains added significance because fossil soils hosting the fossils have long been taken as evidence for a marked rise in the amount of oxygen in the atmosphere at about 2.4 billion to 2.2 billion years ago, widely called the Great Oxidation Event.”

By modern standards, in which Earth’s air is now 21 percent oxygen, this early rise was modest, to about 5 percent oxygen, but it represented a rise from vanishingly low oxygen levels earlier in geological time.

Demonstrating that Diskagma are fossils, Retallack said, was a technical triumph because they were too big to be completely seen in a standard microscopic slide and within rock that was too dark to see through in slabs. The samples were imaged using powerful X-rays of a cyclotron, a particle accelerator, at the Lawrence Berkeley National Laboratory in California.

The images enabled a three-dimensional restoration of the fossils’ form: odd little hollow urn-shaped structures with a terminal cup and basal attachment tube. “At last we have an idea of what life on land looked like in the Precambrian,” Retallack said. “Perhaps with this search image in mind, we can find more and different kinds of fossils in ancient soils.”

In their conclusion, the researchers noted that their newly named fossil Diskagma is comparable in morphology and size to Thucomyces lichenoides, a fossil dating to 2.8 billion years ago and also found in South Africa, but its composition, including interior structure and trace elements, is significantly different.

Diskagma also holds some similarities to three living organisms, which were illustrated microscopically in the study: the slime mold Leocarpus fragilis as found in Oregon’s Three Sisters Wilderness; the lichen Cladonia ecmocyna gathered near Fishtrap Lake in Montana; and the fungus Geosiphon pyriformis from near Darmstadt, Germany.

The new fossil, the authors concluded, is a promising candidate for the oldest known eukaryote –an organism with cells that contain complex structures, including a nucleus, within membranes.

“Researchers at the UO are collaborating with scientists from around the world to create new knowledge with far-reaching applications,” said Kimberly Andrews Espy, UO vice president for research and innovation, and dean of the graduate school. “This research by Dr. Retallack and his team opens new doors of inquiry about the origins of ancient life on Earth.”

Evidence for Avian Intrathoracic Air Sacs in a New Predatory Dinosaur from Argentina

July 22nd, 2013

Riffin

Background

Living birds possess a unique heterogeneous pulmonary system composed of a rigid, dorsally-anchored lung and several compliant air sacs that operate as bellows, driving inspired air through the lung. Evidence from the fossil record for the origin and evolution of this system is extremely limited, because lungs do not fossilize and because the bellow-like air sacs in living birds only rarely penetrate (pneumatize) skeletal bone and thus leave a record of their presence.

Methodology/Principal Findings

We describe a new predatory dinosaur from Upper Cretaceous rocks in Argentina, Aerosteon riocoloradensis gen. et sp. nov., that exhibits extreme pneumatization of skeletal bone, including pneumatic hollowing of the furcula and ilium. In living birds, these two bones are pneumatized by diverticulae of air sacs (clavicular, abdominal) that are involved in pulmonary ventilation. We also describe several pneumatized gastralia (“stomach ribs”), which suggest that diverticulae of the air sac system were present in surface tissues of the thorax.

Conclusions/Significance

We present a four-phase model for the evolution of avian air sacs and costosternal-driven lung ventilation based on the known fossil record of theropod dinosaurs and osteological correlates in extant birds:

(1) Phase I—Elaboration of paraxial cervical air sacs in basal theropods no later than the earliest Late Triassic.

(2) Phase II—Differentiation of avian ventilatory air sacs, including both cranial (clavicular air sac) and caudal (abdominal air sac) divisions, in basal tetanurans during the Jurassic. A heterogeneous respiratory tract with compliant air sacs, in turn, suggests the presence of rigid, dorsally attached lungs with flow-through ventilation.

(3) Phase III—Evolution of a primitive costosternal pump in maniraptoriform theropods before the close of the Jurassic.

(4) Phase IV—Evolution of an advanced costosternal pump in maniraptoran theropods before the close of the Jurassic.

In addition, we conclude:

(5) The advent of avian unidirectional lung ventilation is not possible to pinpoint, as osteological correlates have yet to be identified for uni- or bidirectional lung ventilation.

(6) The origin and evolution of avian air sacs may have been driven by one or more of the following three factors: flow-through lung ventilation, locomotory balance, and/or thermal regulation.

Figure 1. Cranial sinus and postcranial air sac systems in birds.

Summary of pneumatic features of the theropod Aerosteon riocoloradensis. show more (A)-Silhouette reconstruction in left lateral view showing preserved bones of the holotype and referred specimens (MCNA-PV-3137-3139); body length approximately 9-10 m. (B)-Left quadrate in posterior view. (C)-Dorsal 14 in left lateral view with enlarged cross-sections of the neural spine and transverse process. (D)-Furcula in anterior view with sagittal cross-section. (E)-Cross-section of medial gastral element from the anterior end of the cuirass showing pneumatocoel. (F)-Left ilium in lateral view with enlarged cross-section of pubic peduncle. Scale bars equal 5 cm in B, 10 cm (3 cm for cross-sections) in C, 10 cm (same for cross-section) in D, 2 cm in E, and 20 cm (6 cm for cross-section) in F. Abbreviations: aqj, articular surface for the quadratojugal; asq, articular surface for the squamosal; bfo, brevis fossa; ca, canal; dipc, diapophyseal canal; ep, epicleideum; hpo, hyposphene; ilb, iliac blade; isped, ischial peduncle; ns, neural spine; pa, parapophysis; pc, pleurocoel; pnec, pneumatocoel; pned, pneumatic depression; pnep, pneumatopore; poap, postacetabular process; poz, postzygapophysis; pped, pubic peduncle; prap, preacetabular process; prz, prezygapophysis; ptfl, pterygoid flange; qc, quadrate condyles; qf, quadrate foramen; qh, quadrate head; se, septum; tp, transverse process. doi:10.1371/journal.pone.0003303.g016

Summary of pneumatic features of the theropod Aerosteon riocoloradensis.
(A)-Silhouette reconstruction in left lateral view showing preserved bones of the holotype and referred specimens (MCNA-PV-3137-3139); body length approximately 9-10 m. (B)-Left quadrate in posterior view. (C)-Dorsal 14 in left lateral view with enlarged cross-sections of the neural spine and transverse process. (D)-Furcula in anterior view with sagittal cross-section. (E)-Cross-section of medial gastral element from the anterior end of the cuirass showing pneumatocoel. (F)-Left ilium in lateral view with enlarged cross-section of pubic peduncle. Scale bars equal 5 cm in B, 10 cm (3 cm for cross-sections) in C, 10 cm (same for cross-section) in D, 2 cm in E, and 20 cm (6 cm for cross-section) in F. Abbreviations: aqj, articular surface for the quadratojugal; asq, articular surface for the squamosal; bfo, brevis fossa; ca, canal; dipc, diapophyseal canal; ep, epicleideum; hpo, hyposphene; ilb, iliac blade; isped, ischial peduncle; ns, neural spine; pa, parapophysis; pc, pleurocoel; pnec, pneumatocoel; pned, pneumatic depression; pnep, pneumatopore; poap, postacetabular process; poz, postzygapophysis; pped, pubic peduncle; prap, preacetabular process; prz, prezygapophysis; ptfl, pterygoid flange; qc, quadrate condyles; qf, quadrate foramen; qh, quadrate head; se, septum; tp, transverse process.
doi:10.1371/journal.pone.0003303.g016

Citation: Sereno PC, Martinez RN, Wilson JA, Varricchio DJ, Alcober OA, et al. (2008) Evidence for Avian Intrathoracic Air Sacs in a New Predatory Dinosaur from Argentina. PLoS ONE 3(9): e3303. doi:10.1371/journal.pone.0003303

Editor: Tom Kemp, University of Oxford, United Kingdom

Geothermal Power Facility Induces Earthquakes, Study Finds

July 21st, 2013

Riffin

An analysis of earthquakes in the area around the Salton Sea Geothermal Field in southern California has found a strong correlation between seismic activity and operations for production of geothermal power, which involve pumping water into and out of an underground reservoir.

“We show that the earthquake rate in the Salton Sea tracks a combination of the volume of fluid removed from the ground for power generation and the volume of wastewater injected,” said Emily Brodsky, a geophysicist at the University of California, Santa Cruz, and lead author of the study, published online in Science on July 11.

“The findings show that we might be able to predict the earthquakes generated by human activities. To do this, we need to take a large view of the system and consider both the water coming in and out of the ground,” said Brodsky, a professor of Earth and planetary sciences at UCSC.

Several geothermal plants are clustered on the southeastern edge of the Salton Sea. (Credit: Image courtesy of Center for Land Use Interpretation)

Brodsky and coauthor Lia Lajoie, who worked on the project as a UCSC graduate student, studied earthquake records for the region from 1981 through 2012. They compared earthquake activity with production data for the geothermal power plant, including records of fluid injection and extraction. The power plant is a “flash-steam facility” which pulls hot water out of the ground, flashes it to steam to run turbines, and recaptures as much water as possible for injection back into the ground. Due to evaporative losses, less water is pumped back in than is pulled out, so the net effect is fluid extraction.

During the period of relatively low-level geothermal operations before 1986, the rate of earthquakes in the region was also low. Seismicity increased as the operations expanded. After 2001, both geothermal operations and seismicity climbed steadily.

The researchers tracked the variation in net extraction over time and compared it to seismic activity. The relationship is complicated because earthquakes are naturally clustered due to local aftershocks, and it can be difficult to separate secondary triggering (aftershocks) from the direct influence of human activities. The researchers developed a statistical method to separate out the aftershocks, allowing them to measure the “background rate” of primary earthquakes over time.

“We found a good correlation between seismicity and net extraction,” Brodsky said. “The correlation was even better when we used a combination of all the information we had on fluid injection and net extraction. The seismicity is clearly tracking the changes in fluid volume in the ground.”

The vast majority of the induced earthquakes are small, and the same is true of earthquakes in general. The key question is what is the biggest earthquake that could occur in the area, Brodsky said. The largest earthquake in the region of the Salton Sea Geothermal Field during the 30-year study period was a magnitude 5.1 earthquake.

The nearby San Andreas fault, however, is capable of unleashing extremely destructive earthquakes of at least magnitude 8, Brodsky said. The location of the geothermal field at the southern end of the San Andreas fault is cause for concern due to the possibility of inducing a damaging earthquake.

“It’s hard to draw a direct line from the geothermal field to effects on the San Andreas fault, but it seems plausible that they could interact,” Brodsky said.

At its southern end, the San Andreas fault runs into the Salton Sea, and it’s not clear what faults there might be beneath the water. A seismically active region known as the Brawley Seismic Zone extends from the southern end of the San Andreas fault to the northern end of the Imperial fault. The Salton Sea Geothermal Field, located on the southeastern edge of the Salton Sea, is one of four operating geothermal fields in the area.