Formation of sedimentary layers of white clay, Tamilnadu, India

Fossil site for wood fossils, Tamilnadu, India

Fossil site in Kerala, 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

Feathery Four-Winged Dinosaur Fossil Found In China Bridges Transition To Birds

September 7th, 2013 Riffin

A fossil of a bird-like dinosaur with four wings has been discovered in northeastern China. The specimen bridges a critical gap in the transition from dinosaurs to birds, and reveals new insights into the origin evolution of feathers.

The transition from dinosaurs to birds is poorly understood because of the lack of well-preserved fossils, and many scientists argue that bird-like dinosaurs appear too late in the fossil record to be the true ancestors of birds.

Top: Fossil of Anchiornis huxleyi from the province of Liaoning, China. Bottom: Artist's rendering. (Credit: Xing Xu)

Top: Fossil of Anchiornis huxleyi from the province of Liaoning, China. Bottom: Artist’s rendering. (Credit: Xing Xu)

In the journal Nature this week, Xing Xu and colleagues describe an exceptionally well-preserved fossil of Anchiornis huxleyi from the province of Liaoning, China. Long feathers cover the arms and tail, but also the feet, suggesting that a four-winged stage may have existed in the transition to birds.

Anchiornis huxleyi was previously thought to be a primitive bird, but closer inspection reveals that it should be assigned to the Troodontidae — a group of dinosaurs closely related to birds.

The authors date the fossil to the earliest Late Jurassic, meaning that it is the oldest bird-like dinosaur reported so far, and older than Archaeopteryx, the earliest known bird.

They conclude that the presence of such a species at this time in the fossil record effectively disputes the argument that bird-like dinosaurs appeared too late to be the ancestors of birds.

525 Million Years Old Fossil Of Sea Creature –Shows Soft Parts of Body Including Tentacles

September 7th, 2013 Riffin

Researchers from China, Leicester and Oxford have discovered a remarkable fossil which sheds new light on an important group of primitive sea creatures.

The 525-million-year-old fossil belongs to a group of tentacle-bearing creatures which lived inside hard tubes. Previously only the tubes have been seen in detail but this new specimen clearly shows the soft parts of the body including tentacles for feeding.

Details of the discovery have just been announced in the journal Current Biology.

This is the detail of 525-million-year-old hemichordate. (Credit: Professor Derek Siveter, Oxford University)

This is the detail of 525-million-year-old hemichordate. (Credit: Professor Derek Siveter, Oxford University)

The creature belongs to a group called pterobranch hemichordates which are related to starfish and sea urchins but also show some characteristics that offer clues to the evolution of the earliest vertebrates. About 30 species of pterobranch are known to exist today although 380-490 million years ago a group of these animals called graptolites were common across the prehistoric oceans.

Pterobranches are creatures which secrete a substance that builds up into a hard tube around their soft body. Tentacles extend from the top of the tube to catch plankton. Although less than 4cm in length, the new fossil is beautifully preserved and minute details can be seen including 36 tiny tentacles along one feathery arm.

Professor David Siveter from the University of Leicester’s Department of Geology commented, “Amazingly, it has exceptionally preserved soft tissues — including arms and tentacles used for feeding — giving unrivalled insight into the ancient biology of the group.”

Colleagues from Yunnan University and the Universities of Leicester and Oxford collaborated in identifying and describing the remarkable find which was discovered in Yunnan Province, China. It has been named Galeaplumosus abilus which means ‘feathered helmet from beyond the clouds’, referring to both the creature’s shape and its location — ‘Yunnan’ literally translates as ‘south of the clouds.’

The team from Yunnan (Professor Hou and Dr Ma), Leicester (Professors David Siveter and Richard Aldridge; Drs Mark Williams and Jan Zalasiewicz) and Oxford (Professor Derek Siveter) are engaged in long term study of these important fossils.

The study was funded by the Royal Society and the National Natural Foundation of China.

Study Reveals Terror Bird “Gastornis” Was Probably a Herbivore

September 6th, 2013 Riffin

It’s a fiercely debated question amongst palaeontologists: was the giant ‘terror bird’, which lived in Europe between 55 to 40 million years ago, really a terrifying predator or just a gentle herbivore?

New research presented at the Goldschmidt conference in Florence today (Thursday 29th August) may finally provide an answer. A team of German researchers has studied fossilised remains of terror birds from a former open-cast brown coal mine in the Geiseltal (Saxony-Anhalt, Germany) and their findings indicate the creature was most likely not a meat eater.

Research shows that the Terror Bird was probably in fact a herbivore. The photo shows a reconstruction of a Terror Bird from Germany, with author Dr. Thomas Tuetkin, University of Bonn. (Credit: Thomas Tuetkin)

Research shows that the Terror Bird was probably in fact a herbivore. The photo shows a reconstruction of a Terror Bird from Germany, with author Dr. Thomas Tuetkin, University of Bonn. (Credit: Thomas Tuetkin)

The terror bird — also known as Gastornis — was a flightless bird up to two metres in height with an enormous, ferocious beak. Based upon its size and ominous appearance, scientists have long assumed that it was a ruthless carnivore.

“The terror bird was thought to have used its huge beak to grab and break the neck of its prey, which is supported by biomechanical modelling of its bite force,” says Dr Thomas Tütken, from the University of Bonn. “It lived after the dinosaurs became extinct and at a time when mammals were at an early stage of evolution and relatively small; thus, the terror bird was though to have been a top predator at that time on land.”

Recent research has cast some doubt on its diet, however. Palaeontologists in the United States found footprints believed to belong to the American cousin of Gastornis, and these do not show the imprints of sharp claws, used to grapple prey, that might be expected of a raptor. Also, the bird’s sheer size and inability to move fast has made some believe it couldn’t have predated on early mammals — though others claim it might have ambushed them. But, without conclusive findings either way, the dietary inclinations of Gastornis remain a mystery.

Dr Tütken and his colleagues Dr Meinolf Hellmund, Dr Stephen Galer and Petra Held have taken a new geochemical approach to determine the diet of Gastornis. By analysing the calcium isotope composition in fossilised bones, they have been able to identify what proportion of a creature’s diet was plant or animal and, on that basis, their position in the food chain of the local ecosystem. This depends on the calcium isotopic composition becoming “lighter” as it passes through the food chain. They tested the method first with herbivorous and carnivorous dinosaurs — including top predator T-Rex — as well as mammals living today, before applying it to terror bird bones held in the Geiseltal collection at Martin-Luther University in Halle.

Their results show that the calcium isotope compositions of terror bird bones are similar to those of herbivorous mammals and dinosaurs and not carnivorous ones. Before the debate is finally closed, however, the researchers want to cross check their data using other fossil assemblages to be completely sure.

“Tooth enamel preserves original geochemical signatures much better than bone, but since Gastornis didn’t have any teeth, we’ve had to work with their bones to do our calcium isotope assay,” explains Dr Tütken. “Because calcium is a major proportion of bone — around 40% by weight — its composition is unlikely to have been affected much by fossilisation. However, we want to be absolutely confident in our findings by analysing known herbivores and carnivores using fossilised bone from the same site and the same time period. This will give us an appropriate reference frame for the terror bird values.”

Prehistoric Climate Shift Linked to Cosmic Impact

September 5th, 2013 Riffin

For the first time, a dramatic climate shift that has long fascinated scientists has been linked to the impact in Quebec of an asteroid or comet, Dartmouth researchers and their colleagues report in a new study funded by the National Science Foundation.

The event took place about 12,900 years ago, at the beginning of the Younger Dryas period, and marks an abrupt global change to a colder, dryer climate, with far-reaching effects on both animals and humans, the scientists say. In North America the big animals, including mastodons, camels, giant ground sloths, and saber-toothed cats, all vanished. Their human hunters, known to archaeologists as the Clovis people, set aside their heavy-duty spears and turned to a hunter-gatherer subsistence diet of roots, berries, and smaller game.

The high temperatures of the meteorite impact 12,900 years ago produced mm-sized spherules of melted glass with the mullite and corundum crystal structure shown here. (Credit: Mukul Sharma)

The high temperatures of the meteorite impact 12,900 years ago produced mm-sized spherules of melted glass with the mullite and corundum crystal structure shown here. (Credit: Mukul Sharma)

“The Younger Dryas cooling is a very intriguing event that impacted human history in a profound manner,” says Mukul Sharma, a professor in the Department of Earth Sciences and one of the authors of a new paper published in the Proceedings of the National Academy of Sciences (PNAS). “Environmental stresses may also have caused Natufians in the Near East to settle down for the first time and pursue agriculture.”

That these powerful environmental changes occurred is not in dispute, but there has been controversy over why they happened. The new PNAS paper focuses on one cause: a comet or meteor striking Earth.

The classical view of the Younger Dryas cooling interlude has been that a surge of meltwater from the North American ice sheet was behind it all. According to this theory, a large quantity of fresh water accumulated behind an ice dam. The dam suddenly ruptured and dumped all this water into the Atlantic Ocean. The sudden influx is thought to have shut down the ocean currents that move tropical water northward, resulting in the cold, dry climate of the Younger Dryas.

However, Sharma and his colleagues from Dartmouth and other institutions have discovered conclusive evidence linking an extraterrestrial impact with this environmental transformation. The PNAS paper presents a scenario in which a meteor or a comet collided with Earth.

The report focuses on spherules, droplets of solidified molten rock expelled by the impact. The spherules in question were recovered from Younger Dryas boundary layers at sites in Pennsylvania and New Jersey, the layers having been deposited at the beginning of the period. The geochemistry and mineralogy profiles of the spherules are identical to rock found in southern Quebec, where Sharma and his colleagues say the impact took place.

“What is exciting in our paper is that we have for the first time narrowed down the region where a Younger Dryas impact did take place,” says Sharma, “even though we have not yet found its crater.” There is a known impact crater in Quebec — the 4-kilometer-wide Corossal crater. However, based on mineralogical and geochemical studies, it is not the impact source for the material found in Pennsylvania and New Jersey.

People have written about many impacts in different parts of the world based on the presence of spherules. “It may well have taken multiple concurrent impacts to bring about the extensive environmental changes of the Younger Dryas,” says Sharma. “However, to date no impact craters have been found, and our research will help track one of them down.”

Fossil Fishes from China Provide First Evidence of Dermal Pelvic Girdles in Osteichthyans

September 4th, 2013 Riffin

The pectoral and pelvic girdles support paired fins and limbs, and have transformed significantly in the diversification of gnathostomes or jawed vertebrates (including osteichthyans, chondrichthyans, acanthodians and placoderms). For instance, changes in the pectoral and pelvic girdles accompanied the transition of fins to limbs as some osteichthyans (a clade that contains the vast majority of vertebrates – bony fishes and tetrapods) ventured from aquatic to terrestrial environments. The fossil record shows that the pectoral girdles of early osteichthyans (e.g., Lophosteus, Andreolepis, Psarolepis and Guiyu) retained part of the primitive gnathostome pectoral girdle condition with spines and/or other dermal components. However, very little is known about the condition of the pelvic girdle in the earliest osteichthyans. Living osteichthyans, like chondrichthyans (cartilaginous fishes), have exclusively endoskeletal pelvic girdles, while dermal pelvic girdle components (plates and/or spines) have so far been found only in some extinct placoderms and acanthodians. Consequently, whether the pectoral and pelvic girdles are primitively similar in osteichthyans cannot be adequately evaluated, and phylogeny-based inferences regarding the primitive pelvic girdle condition in osteichthyans cannot be tested against available fossil evidence.

Figure 1. Guiyu oneiros Zhu et al., 2009. show more A. New articulated specimen of Guiyu oneiros (V17914, lateral view) from the Kuanti Formation (Late Ludlow, Silurian), Qujing, Yunnan, showing a right dermal pelvic girdle in near-natural position. Red arrow points to the anterior end of the fish. B. Interpretative drawing. Abbreviations: ba.sc, basal scales of pelvic fin; cla, clavicle; cle, cleithrum; icl, interclavicle; ipelv, interpelvic plate; pelv.sp, pelvic fin spine; scap, scapulocoracoid; sdf.sp, second dorsal fin spine; tr.anf, lepidotrichia of anal fin; v.dpg, ventral lamina of dermal pelvic girdle; vrs, ventral ridge scale. doi:10.1371/journal.pone.0035103.g001

Figure 1. Guiyu oneiros Zhu et al., 2009.
A. New articulated specimen of Guiyu oneiros (V17914, lateral view) from the Kuanti Formation (Late Ludlow, Silurian), Qujing, Yunnan, showing a right dermal pelvic girdle in near-natural position. Red arrow points to the anterior end of the fish. B. Interpretative drawing. Abbreviations: ba.sc, basal scales of pelvic fin; cla, clavicle; cle, cleithrum; icl, interclavicle; ipelv, interpelvic plate; pelv.sp, pelvic fin spine; scap, scapulocoracoid; sdf.sp, second dorsal fin spine; tr.anf, lepidotrichia of anal fin; v.dpg, ventral lamina of dermal pelvic girdle; vrs, ventral ridge scale.
doi:10.1371/journal.pone.0035103.g001

Figure 2. The holotype (V15541) of Guiyu oneiros Zhu et al., 2009. show more A. Interpretative drawing of the part to show the position of the newly identified left pelvic girdle with dermal and endoskeletal components. B–C. Close-up of the counterpart to show the endoskeletal pelvic girdle in internal view (B) and interpretative drawing (C). D–E. Close-up of the part to show the dermal pelvic girdle in lateral view (D) and interpretative drawing (E). Red arrows point to the anterior end of the fish. The red rectangles indicate the close-up areas in Figure 3A and Figure 3B. The double arrows point to the corresponding positions of the fractured interpelvic plate in part (E) and counterpart (C). Abbreviations: br, branchiostegal ray; b.scu, basal scute; cla, clavicle; cle, cleithrum; dpg, dermal pelvic girdle; endo.pg, endoskeletal pelvic girdle; gu, gular; ipelv, interpelvic plate; l.dpg, lateral lamina of dermal pelvic girdle; lj, lower jaw; m.ext, median extrascapular; mx, maxillary; op, opercular; pa, parietal shield; pf.sp, pelvic fin spine; po, foramina for pterygial nerves and vessels; pop, preopercular; ppa, postparietal shield; sdf.sp, second dorsal fin spine; sop, subopercular; sp, pectoral fin spine; tr, lepidotrichia; v.dpg, ventral lamina of dermal pelvic girdle; vrs, ventral ridge scale. doi:10.1371/journal.pone.0035103.g002

Figure 2. The holotype (V15541) of Guiyu oneiros Zhu et al., 2009.
A. Interpretative drawing of the part to show the position of the newly identified left pelvic girdle with dermal and endoskeletal components. B–C. Close-up of the counterpart to show the endoskeletal pelvic girdle in internal view (B) and interpretative drawing (C). D–E. Close-up of the part to show the dermal pelvic girdle in lateral view (D) and interpretative drawing (E). Red arrows point to the anterior end of the fish. The red rectangles indicate the close-up areas in Figure 3A and Figure 3B. The double arrows point to the corresponding positions of the fractured interpelvic plate in part (E) and counterpart (C). Abbreviations: br, branchiostegal ray; b.scu, basal scute; cla, clavicle; cle, cleithrum; dpg, dermal pelvic girdle; endo.pg, endoskeletal pelvic girdle; gu, gular; ipelv, interpelvic plate; l.dpg, lateral lamina of dermal pelvic girdle; lj, lower jaw; m.ext, median extrascapular; mx, maxillary; op, opercular; pa, parietal shield; pf.sp, pelvic fin spine; po, foramina for pterygial nerves and vessels; pop, preopercular; ppa, postparietal shield; sdf.sp, second dorsal fin spine; sop, subopercular; sp, pectoral fin spine; tr, lepidotrichia; v.dpg, ventral lamina of dermal pelvic girdle; vrs, ventral ridge scale.
doi:10.1371/journal.pone.0035103.g002

Figure 3. Guiyu oneiros Zhu et al., 2009. show more A. Close-up of the holotype (in part) to show the dermal pelvic girdle in lateral view. B. Close-up of the holotype (in counterpart) to show the endoskeletal pelvic girdle in internal view. C. Tentative life restoration in ventral view to show the paired pelvic girdles and unpaired interpelvic plate. Red arrows point to the anterior end of the fish. Abbreviations: endo.pg, endoskeletal pelvic girdle; l.dpg, lateral lamina of dermal pelvic girdle; po, foramina for pterygial nerves and vessels; v.dpg, ventral lamina of dermal pelvic girdle. doi:10.1371/journal.pone.0035103.g003

Figure 3. Guiyu oneiros Zhu et al., 2009.
A. Close-up of the holotype (in part) to show the dermal pelvic girdle in lateral view. B. Close-up of the holotype (in counterpart) to show the endoskeletal pelvic girdle in internal view. C. Tentative life restoration in ventral view to show the paired pelvic girdles and unpaired interpelvic plate. Red arrows point to the anterior end of the fish. Abbreviations: endo.pg, endoskeletal pelvic girdle; l.dpg, lateral lamina of dermal pelvic girdle; po, foramina for pterygial nerves and vessels; v.dpg, ventral lamina of dermal pelvic girdle.
doi:10.1371/journal.pone.0035103.g003

 

Figure 4. Guiyu oneiros Zhu et al., 2009. show more A. Close-up of the three median dorsal plates (Md1-Md3) of the holotype V15541. B–C. A disarticulated third median dorsal plate (Md3) bearing the first dorsal fin spine in external (B) and internal (C) views, V17914.2. D. A disarticulated third median dorsal plate (Md3) in external view, V17914.3. E. Revised restoration of Guiyu oneiros in lateral view, based on [24] for the cranial portion, and new data in this work. Abbreviations: Md1–Md3, first to third median dorsal plates, with the third bearing the first dorsal fin spine and the endoskelatal basal plate. doi:10.1371/journal.pone.0035103.g004

Figure 4. Guiyu oneiros Zhu et al., 2009.
A. Close-up of the three median dorsal plates (Md1-Md3) of the holotype V15541. B–C. A disarticulated third median dorsal plate (Md3) bearing the first dorsal fin spine in external (B) and internal (C) views, V17914.2. D. A disarticulated third median dorsal plate (Md3) in external view, V17914.3. E. Revised restoration of Guiyu oneiros in lateral view, based on [24] for the cranial portion, and new data in this work. Abbreviations: Md1–Md3, first to third median dorsal plates, with the third bearing the first dorsal fin spine and the endoskelatal basal plate.
doi:10.1371/journal.pone.0035103.g004

Methodology/Principal Findings

Here we report the first discovery of spine-bearing dermal pelvic girdles in early osteichthyans, based on a new articulated specimen of Guiyu oneiros from the Late Ludlow (Silurian) Kuanti Formation, Yunnan, as well as a re-examination of the previously described holotype. We also describe disarticulated pelvic girdles of Psarolepis romeri from the Lochkovian (Early Devonian) Xitun Formation, Yunnan, which resemble the previously reported pectoral girdles in having integrated dermal and endoskeletal components with polybasal fin articulation.

Conclusions/Significance

The new findings reveal hitherto unknown similarity in pectoral and pelvic girdles among early osteichthyans, and provide critical information for studying the evolution of pelvic girdles in osteichthyans and other gnathostomes.

Citation: Zhu M, Yu X, Choo B, Qu Q, Jia L, et al. (2012) Fossil Fishes from China Provide First Evidence of Dermal Pelvic Girdles in Osteichthyans. PLoS ONE 7(4): e35103. doi:10.1371/journal.pone.0035103

Editor: Ulrich Joger, State Natural History Museum, Germany

Acoustic Waves Warn of Tsunami

September 2nd, 2013 Riffin

An early warning system against tsunamis has been developed and tailored for the need of the Mediterranean, but preparedness on the ground is paramount to ensuring peoples’ safety.

When a coastal area is about to be hit by the waves of a tsunami, time is everything. The earlier we know where and when it is going to hit the coast, the more chances there are to evacuate the area. Early warning systems play a crucial role. Until now, seismic signals were used to issue such warning. These are subsequently confirmed or cleared by measuring sea level height. This approach stems from the fact that shallow submarine earthquakes exceeding a given magnitude are the most likely causes of tsunamis.

tsunami

tsunami

 

More recently, an EU funded project called NEARESTfound a better way of identifying a tsunami threat at early stage. “To do this we developed a new device we called tsunameter that we put as close as possible to those places where we know that is very likely a tsunami is generated,” says Francesco Chierici, who is the project coordinator and also works as a researcher the Radio Astronomy Institute (IRA), in Bologna, Italy. This tsunameter can be placed close to the geological faults that are responsible for the earthquake and, accordingly, for tsunamis. Detecting a tsunami near its source is crucial “expecially in peculiar environments such as the Mediterranean where the tsunami are generated very close to the coasts,” says Chierici.

 

Every device is connected with a surface buoy and consists of a set of instruments collecting several kinds of data. These include local acceleration and pressure of water, seismic waves, and, in particular, the acoustic waves generated by tsunamis.With this information, actual tsunamis can be distinguished from the background noise, “using a specific mathematical algorithm” which is interpreting the data. Under the project, the tsunameter had been tested for a year off the Gulf of Cadiz in Spain, at water depth of 3,200 metres. Since the project was completed, in March 2010, the tsunameters are now tested in a new research programme called Multidisciplinary Oceanic Information SysTem (MOIST), run by the Italian National Institute of Geophysics and Vulcanology(INGV) in Rome.

The idea of using acoustic waves as tsunami signal is effective, according toStefano Tinti, professor of geology at the University of Bologna, Italy, and an expert in tsunamis. “Their speed of propagation is slower than that of seismic waves, but still quicker than that of the tsunami,” he said. The problem is the technology “is still in an experimental stage and it’s not so easy to separate the hydroacoustic signal from the others when the detector is so close to the source.”

Another issue is the cost of installation and maintenance. “Off-shore detection systems are more expensive than coastal ones,” he adds. Tinti also believes it could be more effective to use the many islands spread around the Mediterranean. “The detection could be of no use in terms of warning system for the very point where the detection takes place,” he contends, “but it is still very useful for other areas of the coast.” The difficulties related to having a costly off-shore observation system are confirmed by Fernando Carrilho of the Portuguese Marine and Atmosphere Institute (IPMA), which was a project partner. When the Portuguese government decided to build a national tsunami early warning system, he explains, experts opted for a cheaper coastal sea-level observation system.

Other experts point out to issues related to providing a timely warning to the population. “Measurements would need to be far enough from the land to be affected to give enough time to raise the alarm,” says Philippe Blondel, acoustic remote sensing expert at the department of physics of the University of Bath, UK. Apart from which early warning system you choose, the difference between saving lives or not is preparedness. “For example, if the Vesuvius erupts and a flank collapses into the sea, this would affect the millions of people in and around Naples, in Italy. Even with the best organisation, there are only so many roads available for people to get away in a hurry,” says Blondel.

A different level of preparedness is required in the Mediterranean, compared to the situation in Japan and United States where “as soon as a tsunami is confirmed as being underway, alarms will sound in all communities likely to be affected,” Blondel explains. Clear evacuation routes have been signposted, he believes, and everybody has been trained to know where to go. He quotes the example of the US West coast, where many long, romantic sandy beaches now have signs every few hundred meters say

Implications of Diet for the Extinction of Saber-Toothed Cats and American Lions

September 1st, 2013 Riffin

The saber-toothed cat, Smilodon fatalis, and American lion, Panthera atrox, were among the largest terrestrial carnivores that lived during the Pleistocene, going extinct along with other megafauna ~12,000 years ago. Previous work suggests that times were difficult at La Brea (California) during the late Pleistocene, as nearly all carnivores have greater incidences of tooth breakage (used to infer greater carcass utilization) compared to today. As Dental Microwear Texture Analysis (DMTA) can differentiate between levels of bone consumption in extant carnivores, we use DMTA to clarify the dietary niches of extinct carnivorans from La Brea. Specifically, we test the hypothesis that times were tough at La Brea with carnivorous taxa utilizing more of the carcasses. Our results show no evidence of bone crushing by P. atrox, with DMTA attributes most similar to the extant cheetah, Acinonyx jubatus, which actively avoids bone. In contrast, S. fatalis has DMTA attributes most similar to the African lion Panthera leo, implying that S. fatalis did not avoid bone to the extent previously suggested by SEM microwear data. DMTA characters most indicative of bone consumption (i.e., complexity and textural fill volume) suggest that carcass utilization by the extinct carnivorans was not necessarily more complete during the Pleistocene at La Brea; thus, times may not have been “tougher” than the present. Additionally, minor to no significant differences in DMTA attributes from older (~30–35 Ka) to younger (~11.5 Ka) deposits offer little evidence that declining prey resources were a primary cause of extinction for these large cats.

Three-dimensional photosimulations of microwear surfaces of all extant and extinct carnivorans analyzed. show more Examples include: (A) A. jubatus (AMNH 161139), (B) P. leo (USNM236919), (C) C. crocuta (AMNH 83592), (D) P. atrox (LACMHC 6996), and (E) S. fatalis (LACMHC 2002-298). doi:10.1371/journal.pone.0052453.g001

Three-dimensional photosimulations of microwear surfaces of all extant and extinct carnivorans analyzed.
Examples include: (A) A. jubatus (AMNH 161139), (B) P. leo (USNM236919), (C) C. crocuta (AMNH 83592), (D) P. atrox (LACMHC 6996), and (E) S. fatalis (LACMHC 2002-298).
doi:10.1371/journal.pone.0052453.g001

Citation: DeSantis LRG, Schubert BW, Scott JR, Ungar PS (2012) Implications of Diet for the Extinction of Saber-Toothed Cats and American Lions. PLoS ONE 7(12): e52453. doi:10.1371/journal.pone.0052453

Editor: Anjali Goswami, University College London, United Kingdom

Earthquakes and Tectonics: First Direct Observation of Subducting Continental Crust During the Collision of Two Continents

August 31st, 2013 Riffin

Earthquake damage to buildings is mainly due to the existing shear waves which transfer their energy during an earthquake to the houses. These shear waves are significantly influenced by the underground and the topography of the surrounding area. Detailed knowledge of the landform and the near-surface underground structure is, therefore, an important prerequisite for a local seismic hazard assessment and for the evaluation of the ground-effect, which can strongly modify and increase local ground motion.

As described in the latest issue of Geophysical Journal International, a team of scientists from the GFZ German Research Center for Geosciences could show that it is possible to map complex shear wave velocity structures almost in real time by means of a newly developed tomgraphic approach.

Cross section through the Earth's crust and mantle in the Pamir. The Pamir mountains are located in the northernmost part of the India-Eurasia collision zone. In this collision zone occur both shallow and deep earthquakes (depicted as white dots). The deep earthquakes are caused by the subduction of lower Eurasian crust. Black triangles: location of the linear seismometer array. (Credit: GFZ)

Cross section through the Earth’s crust and mantle in the Pamir. The Pamir mountains are located in the northernmost part of the India-Eurasia collision zone. In this collision zone occur both shallow and deep earthquakes (depicted as white dots). The deep earthquakes are caused by the subduction of lower Eurasian crust. Black triangles: location of the linear seismometer array. (Credit: GFZ)

The method is based on ambient seismic noise recordings and analyses. “We use small, hardly noticeable amplitude ground motions as well as anthropogenic ground vibrations,” Marco Pilz, a scientist at GFZ, explains. “With the help of these small signals we can obtain detailed images of the shallow seismic velocity structure.” In particular, images and velocity changes in the underground due to earthquakes and landslides can be obtained in almost real time.

“What is new about our method is the direct calculation of the shear wave velocity. Moreover, we are working on a local, small-scale level — compared to many other studies,” Marco Pilz continues.

This method has already been successfully applied: Many regions of Central Asia are threatened by landslides. Since the shear wave velocity usually drops significantly before a landslide slip this technique offers the chance to monitor changes in landslide prone areas almost in real time.

Further application can be used in earthquake research. The authors were able to map the detailed structure of a section of the Issyk-Ata fault, Kyrgyzstan, which runs along the southern border of the capital city, Bishkek, with a population of approx. 900.000 inhabitants. They showed that close to the surface of the mapped section a splitting into two different small fault branches can be observed. This can influence the pace of expansion or also an eventual halting of the propagation on the main fault.

Central Asia is extensively seismically endangered; the accompanying processes and risks are investigated by the Central-Asian Institute of Applied Geosciences (CAIAG) in Bishkek, a joint institution established by the GFZ and the Kyrgyz government.

Why do these earthquakes occur?

The Pamir and Tien Shan are the result of the crash of two continental plates: the collision of India and Eurasia causes the high mountain ranges. This process is still ongoing today and causes breaking of the Earths crust, of which earthquakes are the consequence.

A second group of GFZ-scientists has investigated together with colleagues from Tajikistan and CAIAG the tectonic process of collision in this region. They were, for the first time, able to image continental crust descending into the Earth’s mantle. In the scientific journal Earth and Planetary Sciences Letters the scientists report that this subduction of continental crust has, to date, never been directly observed. To make their images, the scientists applied a special seismological method (so-called receiver function-analysis) on seismograms that had been collected in a two years long field experiment in the Tien Shan-Pamir-Hindu Kush area. Here, the collision of the Indian and Eurasian plates presents an extreme dimension.

“These extreme conditions cause the Eurasian lower crust to subduct into the Earth’s mantle,” explains Felix Schneider from the GFZ German Research Centre for Geosciences.” Such a subduction can normally be observed during the collision of ocean crust with continental crust, as the ocean floors are heavier than continental rock.”

Findings at the surface of metamorphic rocks that must have arisen from ultra-high pressures deep in the Earth’s mantle also provide evidence for subduction of continental crust in the Pamir region. Furthermore, the question arises, how the occurrence of numerous earthquakes at unusual depths of down to 300 km in the upper mantel can be explained. Through the observation of the subducting part of the Eurasian lower crust, this puzzle could, however, be solved.

First Known Feeding Trace of the Eocene Bottom-Dwelling Fish Notogoneus osculus and Its Paleontological Significance

August 30th, 2013 Riffin

The Green River Formation (early Eocene, about 42–53 Ma) at and near Fossil Butte National Monument in Wyoming, USA, is world famous for its exquisitely preserved freshwater teleost fish in the former Fossil Lake. Nonetheless, trace fossils attributed to fish interacting with the lake bottom are apparently rare, and have not been associated directly with any fish species. Here we interpret the first known feeding and swimming trace fossil of the teleost Notogoneus osculus Cope (Teleostei: Gonorynchidae), which is also represented as a body fossil in the same stratum.

Methodology/Principal Findings

A standard description of the trace fossil, identified as Undichna cf. U. simplicatas, was augmented by high-resolution digital images and spatial and mathematical analyses, which allowed for detailed interpretations of the anatomy, swimming mode, feeding behavior, and body size of the tracemaker. Our analysis indicates that the tracemaker was about 45 cm long; used its caudal, anal, and pelvic fins (the posterior half of its body) to make the swimming traces; and used a ventrally oriented mouth to make overlapping feeding marks. We hypothesize that the tracemaker was an adult Notogoneus osculus.

Trace fossil specimen FOBU-12718

Trace fossil specimen FOBU-12718

 

Model fit and parameter estimates for each waveform associated with traces in FOBU-12718.

Model fit and parameter estimates for each waveform associated with traces in FOBU-12718.

 

Close-up views of feeding trace in FOBU-12718. show more A – Overall sketch map of trace fossil, made by tracing on mylar sheet above original slab, with detailed inset (colored) for B indicated. B – Close-up of inset area in A and focus on mouth marks (box); LPF = left pelvic fin, RPF = right pelvic fin, AF = anal fin, CF = caudal fin; bar scale = 1 cm. C – Outlines of mouth traces, showing overlapping elliptical traces, based on disturbance patterns of underlying lamina; arrow indicates direction of movement in feeding; bar scale = 1 cm. doi:10.1371/journal.pone.0010420.g003

Close-up views of feeding trace in FOBU-12718.
A – Overall sketch map of trace fossil, made by tracing on mylar sheet above original slab, with detailed inset (colored) for B indicated. B – Close-up of inset area in A and focus on mouth marks (box); LPF = left pelvic fin, RPF = right pelvic fin, AF = anal fin, CF = caudal fin; bar scale = 1 cm. C – Outlines of mouth traces, showing overlapping elliptical traces, based on disturbance patterns of underlying lamina; arrow indicates direction of movement in feeding; bar scale = 1 cm.
doi:10.1371/journal.pone.0010420.g003

 

Full-size (53-cm long) adult specimen of Notogoneus osculus Cope, about 13% longer than the tracemaker interpreted for the trace fossil FOBU-12718; scale in centimeters. show more Specimen is in Fossil Butte National Monument collection; photograph by Arvid Aase. doi:10.1371/journal.pone.0010420.g004

Full-size (53-cm long) adult specimen of Notogoneus osculus Cope, about 13% longer than the tracemaker interpreted for the trace fossil FOBU-12718; scale in centimeters.
Specimen is in Fossil Butte National Monument collection; photograph by Arvid Aase.
doi:10.1371/journal.pone.0010420.g004

 

Artistic recreation of Notogoneus osculus forming the swimming-feeding trace fossil FOBU-12718, viewed from above. show more doi:10.1371/journal.pone.0010420.g005

Artistic recreation of Notogoneus osculus forming the swimming-feeding trace fossil FOBU-12718, viewed from above.
doi:10.1371/journal.pone.0010420.g005

 

Conclusions/Significance

Our results are the first to link a specific teleost tracemaker with a trace fossil from the Green River Formation, while also interpreting the size and relative age of the tracemaker. The normal feeding and swimming behaviors indicated by the trace fossil indicate temporarily oxygenated benthic conditions in the deepest part of Fossil Lake, counter to most paleoecological interpretations of this deposit. Lastly, our spatial and mathematical analyses significantly update and advance previous approaches to the study of teleost trace fossils.

Citation: Martin AJ, Vazquez-Prokopec GM, Page M (2010) First Known Feeding Trace of the Eocene Bottom-Dwelling Fish Notogoneus osculus and Its Paleontological Significance. PLoS ONE 5(5): e10420. doi:10.1371/journal.pone.0010420

Editor: Andrew Allen Farke, Raymond M. Alf Museum of Paleontology, United States of America

 

Supervolcanic Ash Can Turn to Lava Miles from Eruption

August 29th, 2013 Riffin

Supervolcanoes, such as the one sitting dormant under Yellowstone National Park, are capable of producing eruptions thousands of times more powerful than normal volcanic eruptions. While they only happen every several thousand years, these eruptions have the potential to kill millions of people and animals due to the massive amount of heat and ash they release into the atmosphere. Now, researchers at the University of Missouri have shown that the ash produced by supervolcanoes can be so hot that it has the ability to turn back into lava once it hits the ground tens of miles away from the original eruption.

Evidence of flowing lava hardened into rock found in Idaho several miles away from the site of an 8 million year old supervolcano eruption at Yellowstone. (Credit: Graham Andrews, assistant professor at California State University Bakersfield.

Evidence of flowing lava hardened into rock found in Idaho several miles away from the site of an 8 million year old supervolcano eruption at Yellowstone. (Credit: Graham Andrews, assistant professor at California State University Bakersfield.

Following a volcanic eruption, lava typically flows directly from the site of the eruption until it cools enough that it hardens in place. However, researchers found evidence of an ancient lava flow tens of miles away from a supervolcano eruption near Yellowstone that occurred around 8 million years ago. Previously, Graham Andrews, an assistant professor at California State University Bakersfield, found that this lava flow was made of ash ejected during the eruption. Following Andrew’s discovery, Alan Whittington, an associate professor in the University of Missouri department of geological sciences in the College of Arts and Science, along with lead author Genevieve Robert and Jiyang Ye, both doctoral students in the geological sciences department, determined how this was possible.

“During a supervolcano eruption, pyroclastic flows, which are giant clouds of very hot ash and rock, travel away from the volcano at typically a hundred miles an hour,” Robert said. “We determined the ash must have been exceptionally hot so that it could actually turn into lava and flow before it eventually cooled.”

Because the ash should have cooled too much in the air to turn into lava right as it landed, the researchers believe the phenomenon was made possible by a process known as “viscous heating.” Viscosity is the degree to which a liquid resists flow. The higher the viscosity, the less the substance can flow. For example, water has a very low viscosity, so it flows very easily, while molasses has a higher viscosity and flows much slower. Whittington likens the process of viscous heating to stirring a pot of molasses.

“It is very hard to stir a pot of molasses and you have to use a lot of energy and strength to move your spoon around the pot,” Whittington said. “However, once you get the pot stirring, the energy you are using to move the spoon is transferred into the molasses, which actually heats up a little bit. This is viscous heating. So when you think about how fast the hot ash is traveling after a massive supervolcano eruption, once it hits the ground that energy is turned into heat, much like the energy from the spoon heating up the molasses. This extra heat created by viscous heating is enough to cause the ash to weld together and actually begin flowing as lava.”

The volcanic ash from this eruption has to be at least 1,500 degrees Fahrenheit to turn into lava; however, since the ash should have lost some of that heat in the air, the researchers believe viscous heating accounted for 200 to 400 degrees Fahrenheit of additional heating to turn the ash into lava.

Robert, Andrews, Ye, and Whittington’s paper was published in Geology. The National Science Foundation funded this research through a CAREER award to Whittington.

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