The Brahmaputra is a trans-boundary river and one of the major rivers of Asia. Majuli is the Riverine island formed by River Brahmaputra in Assam in India.
With its origin in the Angsi Glacier, located on the northern side of the Himalayas in Burang County of Tibet as the Yarlung Tsangpo River, it flows across southern Tibet to break through the Himalayas in great gorges (including the Yarlung Tsangpo Grand Canyon) and into Arunachal Pradesh (India) where it is known as Dihang or Siang. It flows southwest through the Assam Valley as Brahmaputra and south through Bangladesh as the Jamuna (not to be mistaken with Yamuna of India). In the vast Ganges Delta it merges with the Padma, the main distributary of the Ganges, then the Meghna, before emptying into the Bay of Bengal.
About 1,800 miles (2,900 km) long, the Brahmaputra is an important river for irrigation and transportation. The average depth of the river is 124 feet (38 m) and maximum depth is 380 feet (120 m). The river is prone to catastrophic flooding in spring when the Himalayan snows melt. The average discharge of the river is about 19,300 cubic metres per second (680,000 cu ft/s), and floods can reach over 100,000 cubic metres per second (3,500,000 cu ft/s). It is a classic example of a braided river and is highly susceptible to channel migration and avulsion. It is also one of the few rivers in the world that exhibit a tidal bore. It is navigable for most of its length.
The river drains the Himalaya east of the Indo-Nepal border, southern-central portion of the Tibetan plateau above the Ganges basin, south-eastern portion of Tibet, the Patkai-Bum hills, the northern slopes of the Meghalaya hills, the Assam plains and the northern portion of Bangladesh. The basin, especially south of Tibet is characterized by high levels of rainfall. Kangchenjunga (8,586m) is the only peak above 8,000m and the highest point within the Brahmaputra basin.
The Brahmaputra’s upper course was long unknown, and its identity with the Yarlung Tsangpo was only established by exploration in 1884–86. This river is often called Tsangpo-Brahmaputra river.
The lower reaches are sacred to Hindus. While most rivers on the Indian subcontinent have female names, this river has a rare male name, as it means “son of Brahma” in Sanskrit (putra means “son”).
Note : The above story is based on materials provided by Wikipedia
Could the humble hadrosaur outrun the mighty T. Rex in an endurance race? UAlberta paleontologists think so, based on their new study of the dinosaurs’ bone and muscle structure. Credit: Niroot Puttapipat
If you ever find yourself wandering lost in Jurassic Park or time-warped back 70 million years, University of Alberta paleontologists Scott Persons and Phil Currie are two guys you would want with you. The two scientists have just published a new paper on tyrannosaur avoidance strategies, looking into how other dinosaurs coexisted with the colossal carnivores and offering new insight into a prehistoric mystery of survival.
“When it comes to avoiding predators, big animals have it hard,” says lead author Scott Persons, a graduate student in the Department of Biological Sciences. “When trouble comes, tiny creatures can hide in the bushes, run up a tree or escape inside a burrow, but an animal the size of a big herbivorous dinosaur couldn’t exactly conceal itself behind the nearest shrub or beneath a convenient rock or tree root.”
Instead, most families of plant-eating dinosaurs evolved specific adaptations to help them cope with their meat-eating adversaries. Some, like Triceratops, evolved big horns that made them too dangerous to attack. Others evolved bony suits of spiky armour that turned them into walking fortresses. A few others evolved lightweight bodies and extra-long legs that gave them the speed to reliably outrun predators. But one group has always appeared virtually defenceless: the hadrosaurs—better known as the duck-billed dinosaurs.
“Hadrosaurs have no horns, no tusks, no big claws and no armour,” says Persons. “They were social animals and lived in large herds. But safety in numbers only goes so far, and to a T. Rex, a big herd of unarmed hadrosaurs would seem like a buffet.”
And yet, hadrosaurs did not simply survive alongside tyrannosaurs—they thrived. In the badlands of Alberta and in many other dinosaur fossil beds across North America and Asia, hadrosaur bones outnumber all other large dinosaur fossils combined. What were they doing right?
“If duck-bills couldn’t hide and couldn’t fight, maybe they could run,” Persons explains. “Compared with other herbivorous heavyweights, hadrosaurs do have proportionately longer leg bones, which indicates faster running. But hadrosaur limb proportions still seem downright poky when you compare them to tyrannosaurs.”
A breakthrough came when Persons looked beyond the bones and considered muscles. Using digital modelling techniques and muscle insertion clues from skeletons, Persons was able to estimate the size and shape of the primary leg muscles of hadrosaurs and tyrannosaurs. He found that both groups had adaptations to support a supersized set of running muscles.
“Their primary running muscle is called the caudofemoralis, and it’s positioned at the base of the tail,” Persons says. “Both hadrosaurs and their predators had an expanded caudofemoralis, but there was a critical difference: in hadrosaurs the muscle was expanded downwards, whereas in tyrannosaurs it was expanded upwards. The upward-expanded muscles attached high on the thigh; the downward-expanded muscles attached low. These up versus down expansions were not just two equally good solutions to the same problem. They imparted two very different running abilities.”
“Imagine we go to the Dino Derby,” Persons muses. “In a race between a tyrannosaur and a hadrosaur, it used to be that the smart money was all on the tyrannosaur. Well, bang! The race begins and, sure enough, with longer legs the tyrannosaur bursts out of the starting gate and into an early lead. With a high attachment, it only takes a short, quick contraction of the caudofemoralis muscle to pull the leg through a single long stride. The low attachment of the hadrosaur only permits shorter, slower strides. The tyrannosaur leaves the duck-bill in its dust. But . . . suppose the race isn’t just a quick sprint. Suppose it’s a full lap or two around the track. Although the tyrannosaur has a higher top speed, it cannot keep up the pace. The low attachment of the hadrosaur’s caudofemoralis gives the muscle great leverage. That translates into much better endurance. It’s like a prehistoric version of Aesop’s fable: the slow but steady hadrosaur wins the race.”
How did superior endurance running keep hadrosaurs from becoming easy pickings for faster tyrannosaurs? Here the U of A researchers draw a comparison with modern zebras. Like hadrosaurs, zebras are often the most abundant big herbivores in their environments, despite having no horns or armour. And although zebras are fast, their top speed is well below that of the lions and cheetahs that prey on them.
“But big cats have terrible endurance and tire out quickly,” Persons concludes. “Zebras can avoid being caught if they start to run before the cats can sneak into their very short effective striking distance. An alert herd can help with that. I think endurance running could have been an even better predator avoidance strategy for hadrosaurs. After all, the limitations of big size work both ways. Zebras have to be on the lookout for stealthy cats lurking in tall grass, but hadrosaurs had only to spot predators that were the size of billboards.”
Persons’ and Currie’s research in the Faculty of Science was published this week in a special compendium of research papers on hadrosaurs produced by Indiana University Press.
Note : The above story is based on materials provided by University of Alberta
Calvin Miller (Vanderbilt University) at the Hverir geothermal area in Northern Iceland, looking at a subglacially erupted table mountain in the distance [note: I can verify the name of the table mountain tomorrow when I’m back in the office]. Credit: Tamara Carley.How do you take the temperature of the Earth billions of years ago? The answer lies in the rocks.
If we can find minerals that formed during the period we are interested in, they can give us clues about the origin and evolution of the magmas from which they crystallized. That information, in turn, can provide valuable evidence of the conditions on the Earth’s surface at the time the magma was generated. This insight into ancient environments is critical to understanding when conditions on Earth were first hospitable to life.
A new study compares Hadean Earth (more than four billion years ago) to the modern Earth that we are familiar with today. This is not a new idea; people have long thought that Hadean Earth might be similar to modern Iceland, where magmatism runs rampant, volcanoes are active, the crust is anomalously thick, and rocks associated with continents (rhyolite, granite) are found in the ocean (seemingly out of place). The study demonstrates just how different Iceland and the Hadean really are, but how similar the Hadean may have been to other environments that are more typical of modern Earth.
Researchers found this out by analyzing zircon, a mineral that crystallizes in the kinds of magmas associated with continental crust. Zircons have been analyzed from all around the world, in many different magmatic and tectonic environments, and from all chapters of Earth’s history. However, until recently, zircons from Iceland have not been the focus of rigorous study. The conclusion, when Hadean zircons were compared to Icelandic zircons? Magmas in the Hadean Earth were likely formed in environments much cooler and wetter (some might say, more hospitable) than the magmatic environments of modern Iceland.
“Zircon is a phenomenal research tool—a reliable little time capsule,” said Lafayette College geoscientist Tamara Carley, who did the research while finishing her doctorate at Vanderbilt University. “It can tell you a lot about magmatic conditions at the time of its crystallization.”
The research was recently published in the scientific journal Earth and Planetary Science Letters.
Finding the early rocks
The challenge in researching early Earth is the paucity of information available. Earth’s earliest rocks have been all but lost to the geologic record, and have been severely altered or totally destroyed by surficial and tectonic processes that continue to shape our planet today. Traditionally, this absence of rocks from the oldest chapter of Earth’s history led researchers to believe that early Earth was covered in a harsh environment, like a global lava ocean, that would be totally inhospitable to rocks and life alike.
In the 1980s, however, the vision of early Earth began to change. Researchers discovered zircon crystals that had crystallized in magmas during the Hadean, then survived Earth’s tumultuous geologic history for more than four billion years. The age of the crystals was confirmed using dating techniques that measure the proportion of radioactive and radiogenic isotopes (parent and daughter isotopes) inside the crystals. Isotopes decay in a predictable fashion over millions or billions of years, and zircon does a good job of locking in this valuable evidence, providing researchers with an accurate clock of the age of the crystals.
Carley’s group did a literature review of the oxygen isotope and trace element geochemistry data teased from these ancient zircon crystals. They then compared the published Hadean results to their new Icelandic findings. Upon realizing just how different Icelandic and Hadean zircons are (and thus, how different their formation environments were), they scoured the literature for zircons that acted as a better modern analogue for the Hadean. They considered the Andes in South America; the Cascade Mountains, the Sierra Nevada Mountains and the Yellowstone Hotspot in western North America; the Mid-Atlantic Ridge; and volcanic rocks in the East African Rift Zone.
The Hadean has temperatures and other compositional clues that are more similar to zircons from subduction zones magmas, generated in areas where one tectonic plate is forced beneath the other when they collide, as happens in places like the Cascades and the Andes. They concluded that Iceland is most similar to other rift environments, which perhaps isn’t much of a surprise since it sits atop a rift itself.
From their look at other researchers’ published work, Carley said her team concurs with what the other researchers found: zircons from the Hadean crystallized at relatively low magmatic temperatures. Furthermore, oxygen isotope ratios measured in the zircon crystals acts as evidence that low-temperature surface water played a role in the generation of the magmas from which they grew. Icelandic zircons, on the other hand, crystallized at much higher temperatures, and have isotopic evidence of hot, hydrothermal waters playing a role in magma genesis. Zircons from Iceland and the Hadean tell very different stories, about their respective environments of origin. Zircons from subduction zone volcanoes (like the Cascades) are more in line with zircons from the Hadean.
“It’s pretty compelling evidence that Earth was cool enough, and perhaps wet enough early on in its history that the thought of early life isn’t crazy,” Carley said.
How similar is Iceland?
Iceland is a standout location on modern Earth, Carley pointed out. It sits at the junction of a mid-ocean ridge and a hotspot, making it a location of elevated heat and magma generation. It has more rhyolite and granite (rocks associated with continental crust) than is common in an oceanic setting. It also features an extra-thick crust, estimated to be about 16 to 19 miles thick (25 to 30 kilometers) compared to the average oceanic crust, which is 4.4 miles (seven kilometers) thick.
Differences also show up after comparing not-so-subtle differences in chemistry between the Icelandic and the ancient zircon populations. In an ideal world, a zircon mineral would only contain three elements: zirconium, oxygen, and silicon. However, trace amounts of other elements (like titanium and uranium) can be trapped in the mineral as it grows. The specific element and its composition all depends on the conditions of the magma as the zircon crystallizes. In this case, titanium was one element that helped give the game away. In comparing hundreds of Icelandic and Hadean zircons, Carley’s research team found that Icelandic zircons consistently were richer in titanium. This told them that the Icelandic zircons grew in hotter magmas compared to the Hadean zircons, which grew in cooler magmas.
Even more exciting than the temperature story told by titanium was the water story told by oxygen isotope ratios, locked in the zircon crystal structure. The zircon record revealed to Carley and her research team that liquid water (essential to life as we know it on Earth) played a major role in both Icelandic and ancient magmas.
But the waters were very different in both cases. In the Hadean, the water involved in the magma generating process appear to be cool, like we see at modern-day subduction zones (like the Cascadeds and the Andes), as opposed to very hot, like we see in Iceland with its active, high-temperature, hydrothermal systems. “It become clear to us that Iceland is very dissimilar to the Hadean,” Carley said. “We need to change the conversation, and we need to stop saying that Iceland is a modern analogue for the Hadean.”The field, she added, could benefit from examining zircons from other locations on Earth, such as collisional zones where subduction does not occur, and juvenile subduction zones that form volcanic islands. These are research directions she said she hopes to pursue in the future.
Reference:
Tamara L. Carley, Calvin F. Miller, Joseph L. Wooden, Abraham J. Padilla, Axel K. Schmitt, Rita C. Economos, Ilya N. Bindeman, Brennan T. Jordan, “Iceland is not a magmatic analog for the Hadean: Evidence from the zircon record,” Earth and Planetary Science Letters, Volume 405, 1 November 2014, Pages 85-97, ISSN 0012-821X, dx.doi.org/10.1016/j.epsl.2014.08.015.
Note : The above story is based on materials provided by Astrobio.net This story is republished courtesy of NASA’s Astrobiology Magazine.
Research vessel on Lake Matano, Indonesia. Sean Crowe, University of British Columbia. Credit: Image courtesy of University of Faculty of Science British Columbia
Earth’s ancient oceans held much lower concentrations of sulfate — a key biological nutrient — than previously recognized, according to research published this week in Science.
The findings paint a new portrait of our planet’s early biosphere and primitive marine life. Organisms require sulfur as a nutrient, and it plays a central role in regulating atmospheric chemistry and global climate.
“Our findings are a fraction of previous estimates, and thousands of time lower than current seawater levels,” says Sean Crowe, a lead author of the study and an assistant professor in the Departments of Microbiology and Immunology, and Earth, Ocean and Atmospheric Sciences at the University of British Columbia.
“At these trace amounts, sulfate would have been poorly mixed and short-lived in the oceans — and this sulfate scarcity would have shaped the nature, activity and evolution of early life on Earth.”
UBC, University of Southern Denmark, CalTech, University of Minnesota Duluth, and University of Maryland researchers used new techniques and models to calibrate fingerprints of bacterial sulfur metabolisms in Lake Matano, Indonesia — a modern lake with chemistry similar to Earth’s early oceans.
Measuring these fingerprints in rocks older than 2.5 billion years, they discovered sulfate 80 times lower than previously thought.
The more sensitive fingerprinting provides a powerful tool to search for sulfur metabolisms deep in Earth’s history or on other planets like Mars.
Findings
Previous research has suggested that Archean sulfate levels were as low as 200 micromolar — concentrations at which sulfur would still have been abundantly available to early marine life.
The new results indicate levels were likely less than 2.5 micromolar, thousands of times lower than today.
What the researchers did
Researchers used state-of-the-art mass spectrometric approaches developed at California Institute of Technology to demonstrate that microorganisms fractionate sulfur isotopes at concentrations orders of magnitude lower than previously recognized.
They found that microbial sulfur metabolisms impart large fingerprints even when sulfate is scarce.
The team used the techniques on samples from Lake Matano, Indonesia — a sulfate-poor modern analogue for the Earth’s Archean oceans.
“New measurements in these unique modern environments allow us to use numerical models to reconstruct ancient ocean chemistry with unprecedented resolution” says Sergei Katsev an Associate Professor at the Large Lakes Observatory, University of Minnesota Duluth.
Using models informed by sulfate isotope fractionation in Lake Matano, they established a new calibration for sulfate isotope fractionation that is extensible to the Earth’s oceans throughout history. The researchers then reconstructed Archean seawater sulfate concentrations using these models and an exhaustive compilation of sulfur isotope data from Archean sedimentary rocks.
Crowe initiated the research while a post-doctoral fellow with Donald Canfield at the University of Southern Denmark.
Reference:
S. A. Crowe, G. Paris, S. Katsev, C. Jones, S.-T. Kim, A. L. Zerkle, S. Nomosatryo, D. A. Fowle, J. F. Adkins, A. L. Sessions, J. Farquhar, D. E. Canfield. Sulfate was a trace constituent of Archean seawater. Science, 2014; 346 (6210): 735 DOI: 10.1126/science.1258966
Note : The above story is based on materials provided by University of Faculty of Science British Columbia.
BIF from the Nuvvuagittuq Supracrustal Belt in Quebec, Canada. This belt contains the oldest supracrustals (sedimentary and volcanic rocks) thus far reported. Credit: Ernesto Percoits
A new study examines how Earth’s oldest iron formations could have been formed before oxygenic photosynthesis played a role in oxidizing iron.
Geology tells us a great deal about the history and evolution of life on our planet. By studying formations in the rock record, astrobiologists can uncover important clues about the history of habitability on Earth.
Of particular interest to astrobiologists are iron formations, which existed on Earth at key periods in the evolution of life. These sedimentary rocks are made of layers of material that contain at least 15% iron, which is mixed into layers of quartz or carbonate. Geologists recognize two types of iron formations: the Algoma-type and the larger Superior-type.
Algoma-type formations are linked to volcanism deep in the oceans, whereas Superior-type formations were formed near the shore in continental shelf environments and contain few volcanic rocks.
Superior-type formations first appear on Earth in the Late Archean (2.7 billion years ago) – at the same time the continents began to rise. These formations were huge and prevailed until 2.4 billion years ago (the Early Paleoproterozoic).
At this time, the Earth was undergoing big changes, including oxygenation of the atmosphere. Because the Earth was changing so much, the ways in which superior-type formations were created between 2.7-2.4 billion years ago may have also varied – particularly in respect to the time periods before and after the atmosphere became rich in oxygen and photosynthesis became a dominant process on Earth.
After the rise of oxygen, oxygenic photosynthetic bacteria are thought to have played a big role in the creation of iron formations. But how were iron formations made before advent of oxygenic photosynthesis?
The new study addresses this question by examining how iron deposition could have occurred without biology (a process known as abiological iron deposition).
One mechanism for abiological iron deposition is a reaction in the atmosphere that creates hydrogen peroxide (a well-known powerful oxidant), which can then oxidize ferrous iron in seawater. Researchers modeled how much hydrogen peroxide could have been produced in the Eoarchean atmosphere of the Earth in order to see if this process could have played a major role in creating ancient iron formations.
According to the paper, published in Geobiology, the amount of hydrogen peroxide simply wasn’t enough to account for the iron formations we now see in the geological record.
“What we concluded is that, by discounting hydrogen peroxide oxidation, anoxygenic photosynthetic micro-organisms are the most likely mechanism responsible for Earth’s oldest iron formations,” Ernesto Pecoits of the Université Paris Diderot and lead author on the study told astrobio.net.
Microorganisms that photosynthesize in the absence of oxygen assimilate carbon by using iron oxide (Fe(II)) as an electron donor instead of water. While oxygenic photosynthesis produces oxygen in the atmosphere (in the form of dioxygen), anoxygenic photosynthesis adds an electron to Fe(II) to produce Fe(III).
“In other words, they oxidize the iron,” explains Pecoits. “This finding is very important because it implies that this metabolism was already active back in the early Archean (ca. 3.8 Byr-ago).”
Reference:
Pecoits et al. (2014) “Atmospheric hydrogen peroxide and Eoarchean iron formations.” Geobiology, DOI: 10.1111/gbi.12116
Note : The above story is based on materials provided by Astrobio.net This story is republished courtesy of NASA’s Astrobiology Magazine.
A Computed Tomography rendering of a snapping turtle (Chelydra serpentina) showing the skeleton (white), lungs (blue), and abdominal muscles (red and pink) used to ventilate the lungs. Because turtles have locked their ribs up into the iconic turtle shell, they can no longer use their ribs to breathe as in most other animals and instead have developed a unique abdominal muscle based system. Credit: Emma R. Schachner
Through the careful study of modern and early fossil tortoise, researchers now have a better understanding of how tortoises breathe and the evolutionary processes that helped shape their unique breathing apparatus and tortoise shell. The findings published in a paper, titled: Origin of the unique ventilatory apparatus of turtles, in the scientific journal, Nature Communications, on Friday, 7 November 2014, help determine when and how the unique breathing apparatus of tortoises evolved.
Lead author Dr Tyler Lyson of Wits University’s Evolutionary Studies Institute, the Smithsonian Institution and the Denver Museum of Nature and Science said: “Tortoises have a bizarre body plan and one of the more puzzling aspects to this body plan is the fact that tortoises have locked their ribs up into the iconic tortoise shell. No other animal does this and the likely reason is that ribs play such an important role in breathing in most animals including mammals, birds, crocodilians, and lizards.”
Instead tortoises have developed a unique abdominal muscular sling that wraps around their lungs and organs to help them breathe. When and how this mechanism evolved has been unknown.
“It seemed pretty clear that the tortoise shell and breathing mechanism evolved in tandem, but which happened first? It’s a bit of the chicken or the egg causality dilemma,” Lyson said. By studying the anatomy and thin sections (also known as histology), Lyson and his colleagues have shown that the modern tortoise breathing apparatus was already in place in the earliest fossil tortoise, an animal known as Eunotosaurus africanus.
This animal lived in South Africa 260 million years ago and shares many unique features with modern day tortoises, but lacked a shell. A recognisable tortoise shell does not appear for another 50 million years.
Lyson said Eunotosaurus bridges the morphological gap between the early reptile body plan and the highly modified body plan of living tortoises, making it the Archaeopteryx of turtles.
“Named in 1892, Eunotosaurus is one of the earliest tortoise ancestors and is known from early rocks near Beaufort West,” said Professor Bruce Rubidge, Director of the Evolutionary Studies Institute at Wits University and co-author of the paper.
“There are some 50 specimen of Eunotosaurus. The rocks of the Karoo are remarkable in the diversity of fossils of early tortoises they have produced. The fact that we find Eunotosaurus at the base of the Karoo succession strongly suggest that there are more ancestral forms of tortoises still to be discovered in the Karoo,” Rubidge added.
The study suggests that early in the evolution of the tortoise body plan a gradual increase in body wall rigidity produced a division of function between the ribs and abdominal respiratory muscles. As the ribs broadened and stiffened the torso, they became less effective for breathing which caused the abdominal muscles to become specialised for breathing, which in turn freed up the ribs to eventually — approximately 50 million years later — to become fully integrated into the characteristic tortoise shell.
Lyson and his colleagues now plan to investigate reasons why the ribs of early tortoises starting to broaden in the first place. “Broadened ribs are the first step in the general increase in body wall rigidity of early basal tortoises, which ultimately leads to both the evolution of the tortoise shell and this unique way of breathing. We plan to study this key aspect to get a better understanding why the ribs started to broaden.”
Reference:
Tyler R. Lyson, Emma R. Schachner, Jennifer Botha-Brink, Torsten M. Scheyer, Markus Lambertz, G. S. Bever, Bruce S. Rubidge, Kevin de Queiroz. Origin of the unique ventilatory apparatus of turtles. Nature Communications, 2014; 5: 5211 DOI: 10.1038/ncomms6211
Note : The above story is based on materials provided by University of the Witwatersrand.
A Mastodon skeleton on display at the National History Museum of Los Angeles County, July 8, 2010 in Los Angeles, California
An Argentine man digging a well in his yard struck fossils believed to be the bones of a 10,000-year-old mastodon, an extinct mammal.
“We presume this is a mastodon and its ivory tusk, but we still need to do the necessary studies,” said Gines Benitez, head of the regional history museum in San Lorenzo, where the fossils were found.
“I was digging and at one point found something very hard,” the man identified as Alcides said.
“I removed the soil around it and eventually found a huge bone,” he told local media.
San Lorenzo is located in the Pampas lowlands where other mastodons—part of the elephant family—have been discovered, several of which are on display at the history museum.
Pterosaur hunting is illustrated. Credit: Mark Witton
A new study, which teamed cutting-edge engineering techniques with paleontology, has found that take-off capacity may have determined body size limits in extinct flying reptiles. The research simulated pterodactyl flight using computer modeling, and will be presented at the upcoming Society of Vertebrate Paleontology meeting in Berlin. Findings suggest that a pterodactyl with a wingspan of 12m or more would simply not be able to get off the ground.
Pterosaurs (commonly known as pterodactyls) were truly giants of the sky. With wingspans of up to 10m, the largest species may have weighed as much as a quarter of a ton. They would have dwarfed the largest known bird at just one third this size. How could such behemoths stay aloft? What prevented them from becoming even bigger?
These questions sparked a novel partnership between Colin Palmer: entrepreneur, mechanical engineer and now doctoral student at Bristol University (UK); and Mike Habib: anatomist and paleontologist at University of Southern California.
“It has been fascinating to apply an engineering approach to understanding biological systems” says Palmer, who has worked on yachts, hovercraft, sailing vessels and windmills before turning to pterosaurs. “Working with Colin has been particularly rewarding” says paleontologist Habib “as we have complimentary skill sets and come at the problem from different backgrounds.”
The pair used 3D imaging of fossils to create a computer model of a pterosaur with a 6m wingspan. This model was then scaled up to create enlarged models with 9m and 12m wingspans. They were used to estimate the wing strength, flexibility, flying speed and power required for flight in massive pterosaurs.
Pterosaur vs giraffe is illustrated. Credit: Mark Witton
Results showed that even the largest pterosaur model could sustain flight by using intermittent powered flight to find air currents for gliding. It could also slow down sufficiently to make a safe landing because the pterosaurs wing is formed from a flexible membrane.Take-off, on the other hand, proved an entirely greater challenge. Unlike modern birds, pterosaur anatomy suggests that they used both their arms and legs to push themselves off the ground during take-off, a maneuver known as the ‘quadrupedal launch’. However, once wingspans approached 12m, the push-off force required to get the model off the ground was too great.
The challenge of propelling a 400kg animal using a quadrupedal launch kept the 12m-wingspan model strictly on terra firma. Palmer concludes “Getting into the air ultimately limited pterosaur size. Even with their unique four legged launch technique, the iron laws of physics eventually caught up with these all time giants of the cretaceous skies.”
Note : The above story is based on materials provided by Society of Vertebrate Paleontology
Shown at 50X magnification, whitish pyrite — iron sulfite or ‘fool’s gold’ — is embedded in gray carbonate rock, formed in a shallow sea some 2.5 billion years ago. Stable isotopic analysis of this and other samples from the same core produced the first evidence of sulfur-respiring bacteria in rocks of this type and age. Credit: Iadviga Zhelezinskaia
Wriggle your toes in a marsh’s mucky bottom sediment and you’ll probably inhale a rotten egg smell, the distinctive odor of hydrogen sulfide gas. That’s the biochemical signature of sulfur-using bacteria, one of Earth’s most ancient and widespread life forms.
Among scientists who study the early history of our 4.5 billion-year-old planet, there is a vigorous debate about the evolution of sulfur-dependent bacteria. These simple organisms arose at a time when oxygen levels in the atmosphere were less than one-thousandth of what they are now. Living in ocean waters, they respired (or breathed in) sulfate, a sulfur and oxygen compound, instead of free oxygen molecules. But how did that sulfate reach the ocean, and when did it become abundant enough for living things to use it?
New research by University of Maryland geology doctoral student Iadviga Zhelezinskaia offers a surprising answer. Zhelezinskaia is the first researcher to analyze the biochemical signals of sulfur compounds found in 2.5 billion-year-old carbonate rocks from Brazil. The rocks were formed on the ocean floor in a geologic time known as the Neoarchaean Eon. They surfaced when prospectors drilling for gold in Brazil punched a hole into bedrock and pulled out a 590-foot-long core of ancient rocks.
In research published Nov. 7, 2014 in the journal Science, Zhelezinskaia and three co-authors — physicist John Cliff of the University of Western Australia and geologists Alan Kaufman and James Farquhar of UMD — show that bacteria dependent on sulfate were plentiful in some parts of the Neoarchaean ocean, even though sea water typically contained about 1,000 times less sulfate than it does today.
“The samples Iadviga measured carry a very strong signal that sulfur compounds were consumed and altered by living organisms, which was surprising,” says Farquhar. “She also used basic geochemical models to give an idea of how much sulfate was in the oceans, and finds the sulfate concentrations are very low, much lower than previously thought.”
Geologists study sulfur because it is abundant and combines readily with other elements, forming compounds stable enough to be preserved in the geologic record. Sulfur has four naturally occurring stable isotopes — atomic signatures left in the rock record that scientists can use to identify the elements’ different forms. Researchers measuring sulfur isotope ratios in a rock sample can learn whether the sulfur came from the atmosphere, weathering rocks or biological processes. From that information about the sulfur sources, they can deduce important information about the state of the atmosphere, oceans, continents and biosphere when those rocks formed.
Farquhar and other researchers have used sulfur isotope ratios in Neoarchaean rocks to show that soon after this period, Earth’s atmosphere changed. Oxygen levels soared from just a few parts per million to almost their current level, which is around 21 percent of all the gases in the atmosphere. The Brazilian rocks Zhelezinskaia sampled show only trace amounts of oxygen, a sign they were formed before this atmospheric change.
With very little oxygen, the Neoarchaean Earth was a forbidding place for most modern life forms. The continents were probably much drier and dominated by volcanoes that released sulfur dioxide, carbon dioxide, methane and other greenhouse gases. Temperatures probably ranged between 0 and 100 degrees Celsius (32 to 212 degrees Fahrenheit), warm enough for liquid oceans to form and microbes to grow in them.
Rocks 2.5 billion years old or older are extremely rare, so geologists’ understanding of the Neoarchaean are based on a handful of samples from a few small areas, such as Western Australia, South Africa and Brazil. Geologists theorize that Western Australia and South Africa were once part of an ancient supercontinent called Vaalbara. The Brazilian rock samples are comparable in age, but they may not be from the same supercontinent, Zhelezinskaia says.
Most of the Neoarchaean rocks studied are from Western Australia and South Africa and are black shale, which forms when fine dust settles on the sea floor. The Brazilian prospector’s core contains plenty of black shale and a band of carbonate rock, formed below the surface of shallow seas, in a setting that probably resembled today’s Bahama Islands. Black shale usually contains sulfur-bearing pyrite, but carbonate rock typically does not, so geologists have not focused on sulfur signals in Neoarchaean carbonate rocks until now.
Zhelezinskaia “chose to look at a type of rock that others generally avoided, and what she saw was spectacularly different,” said Kaufman. “It really opened our eyes to the implications of this study.”
The Brazilian carbonate rocks’ isotopic ratios showed they formed in ancient seabed containing sulfate from atmospheric sources, not continental rock. And the isotopic ratios also showed that Neoarchaean bacteria were plentiful in the sediment, respiring sulfate and emitted hydrogen sulfide — the same process that goes on today as bacteria recycle decaying organic matter into minerals and gases.
How could the sulfur-dependent bacteria have thrived during a geologic time when sulfur levels were so low? “It seems that they were in shallow water, where evaporation may have been high enough to concentrate the sulfate, and that would make it abundant enough to support the bacteria,” says Zhelezinskaia.
Zhelezinskaia is now analyzing carbonate rocks of the same age from Western Australia and South Africa, to see if the pattern holds true for rocks formed in other shallow water environments. If it does, the results may change scientists’ understanding of one of Earth’s earliest biological processes.
“There is an ongoing debate about when sulfate-reducing bacteria arose and how that fits into the evolution of life on our planet,” says Farquhar. “These rocks are telling us the bacteria were there 2.5 billion years ago, and they were doing something significant enough that we can see them today.”
Reference:
I. Zhelezinskaia, A. J. Kaufman, J. Farquhar, J. Cliff. Large sulfur isotope fractionations associated with Neoarchean microbial sulfate reduction. Science, 2014; 346 (6210): 742 DOI: 10.1126/science.1256211
Note : The above story is based on materials provided by University of Maryland. The original article was written by Heather Dewar.
The front row from left shows: Mouse-deer (Field Museum of Natural History specimen no.68770), Andean mountain cavy (FMNH 53654), American pika (FMNH 12590), Alaskan hare (FMNH 9867). Back row shows: capybara (FMNH 79933). Credit: Photo by S. Tomiya
Closely related groups can differ dramatically in their diversity, but why this happens is a fundamental question in evolutionary biology, dating back to Darwin’s observation that a few hyper-diverse groups dominate the modern biota. One of the most extreme examples of this observation is found in the comparison of rodents (Rodentia) and rabbits (Lagomorpha).
These two mammalian orders are sister groups, but while rodents have diversified to over 2000 living species and an enormous range of body sizes, lagomorphs (rabbits, hares, and pikas) are limited to fewer than 100 relatively small species. A new study presented at the Society of Vertebrate Paleontology Annual Meeting shows, surprisingly, that competition with ungulates (hoofed mammals), intensified by climate change, are to blame for the lagomorphs’ limited diversity.
Susumu Tomiya of the Field Museum of Natural History and Lauren Miller of the University of California at Berkeley were intrigued by the observation that lagomorphs have spread to all continents except Antarctica and inhabit a variety of environments, but the group contains only about 80 living species of small herbivores, compared to roughly 2,000 species of rodents. According to Dr. Tomiya, “Mammalian groups that are ubiquitous at the global scale—rodents and bats, for example—tend to be species-rich and show many different ways of living. Lagomorphs are a paradox in this sense.” Lagomorphs also show a much more limited range of body size and forms relative to rodents: the average weight of the largest living species (Alaskan hare) is approximately 5 kg (11 lb), whereas the largest living rodent (capybara) is twelve times larger at about 60 kg (133 lb). Given that the two groups are each other’s closest evolutionary relatives, and they have been evolving for roughly the same amount of time (~55 million years, give or take a few million years), the difference in their diversity is striking.
Importantly, fossils from Mediterranean islands show that lagomorphs are capable of becoming much larger than seen today. Nuralagus rex from the Pliocene of Minorca is estimated to have weighed about 12 kg. Ecologists and evolutionary biologists have suggested that such gigantism can take place only in absence of competitors, as is sometimes the case with island faunas. They reasoned that, if competition were an important factor in determining body size evolution, the conspicuous absence of giant lagomorphs (by today’s standards) on continents could be explained by long-standing presence of potential competitors, such as ungulates (e.g., horses, deer, cows, pigs, and their extinct relatives).
Tomiya and Miller tested this hypothesis by examining the rich North American fossil record. They compared the trajectories of maximum lagomorph body size and minimum ungulate body size over the last 30 million years, revealing two phases of body size evolution in lagomorphs. In the late Oligocene, the largest lagomorphs (comparable in body mass to medium-sized hares living today) coexisted with similar-sized and even smaller ungulates (some of which were as small as modern-day cottontails). This body-size relationship was fundamentally altered following a major climatic transition that prompted opening-up of forests and establishment of grasslands in the early Miocene. For the next 20 million years or so, the maximum lagomorph size shifted in parallel with the minimum ungulate size, suggesting a dynamic body-size boundary between the two groups maintained by competitive interactions.
This study suggests that competitive interactions (and resulting division of resources that minimizes such interactions) may be a key factor determining diversification of mammals over millions of years. From a broader perspective, this study suggests that large-scale shifts in climate and available habitats can leave a long-lasting impact on the subsequent courses of evolution of major mammalian groups by altering their ecological interactions. As Dr. Tomiya notes, “Much of the discussion about the current biodiversity crisis has revolved around saving species from extinctions. From a paleontological perspective, we believe that it is also important to think about the future of what will turn out to be surviving lineages, that is, how human activities are altering the courses of their evolution through modification of landscapes, seascapes, and atmosphere at the planetary scale. Millions of years from now, our own species may no longer exist, but whatever remains of life on Earth will reflect the decisions we make today about how we live as a species.”
Miller, who measured modern lagomorph specimens to estimate body masses of extinct species, adds that natural history collections are crucial in this sense, “This study highlights the creative ways in which museum specimens can be used to provide data over a longer time sequence. Even something as seemingly old-fashioned as rabbit skins with handwritten weight measurements can be utilized with modern techniques to better understand current conditions and future trajectories of biodiversity.”
Note : The above story is based on materials provided by Society of Vertebrate Paleontology
This is a igitally restored skull of the Cretaceous dinosaur Erlikosaurus andrewsi; complete (front) and disassembled into its individual elements (back). Credit: Image courtesy Journal of Vertebrate Paleontology
Fossils are usually deformed or incompletely preserved when they are found, after sometimes millions of years of fossilization processes. Consequently, fossils have to be studied very carefully to avoid damage, and are sometimes they are difficult to access, as they might be located in remote museum collections. An international team of scientists, led by Dr. Stephan Lautenschlager from the University of Bristol now solved some of these problems by using modern computer technology, as described in a recent issue of the Journal of Vertebrate Paleontology.
This image shows a comparison between originally preserved and digitally restored skull of the Cretaceous dinosaur Erlikosaurus andrewsi. Credit: Image courtesy Journal of Vertebrate PaImage courtesy Journal of Vertebrate Paleontologyleontology
The team consisting of Dr. Stephan Lautenschlager and Professor Emily Rayfield from the University of Bristol, Professor Lindsay Zanno from the North Carolina Museum of Natural Sciences and North Carolina State University, Dr. Perle Altangerel from the National University of Ulaanbaatar, and Professor Lawrence Witmer from Ohio University employed high-resolution X-ray computed tomography (CT scanning) and digital visualisation techniques to restore a rare dinosaur fossil.
Lead author, Dr. Stephan Lautenschlager of Bristol’s School of Earth Sciences said: “With modern computer technology, such as CT scanning and digital visualisation, we now have powerful tools at our disposal, with which we can get a step closer to restore fossil animals to their life-like condition.”
The focus of the study was the skull of Erlikosaurus andrewsi, a 3-4m (10-13ft) large herbivorous dinosaur called a therizinosaur, which lived more than 90 million years ago during the Cretaceous Period in what is now Mongolia.
“The fossil skull of Erlikosaurus andrewsi is one-of-a-kind and the most complete and best preserved example known for this group of dinosaurs. As such it is of high scientific value” explains co-author Professor Emily Rayfield.
This is an original fossil skull of the Cretaceous dinosaur Erlikosaurus andrewsi. Credit: Image courtesy Journal of Vertebrate Paleontology
Using a digital model of the fossil, the team virtually disassembled the skull of Erlikosaurus into its individual elements. Then they digitally filled in any breaks and cracks in the bones, duplicated missing elements and removed deformation by applying retro-deformation techniques, digitally reversing the steps of deformation. In a final step, the reconstructed elements were re-assembled. This approach not only allowed the restoration of the complete skull of Erlikosaurus, but also the study of its individual elements.However, using digital models has further advantages adds Dr. Lawrence Witmer: “Digital models allow the study of the external and internal features of a fossil. Furthermore, they can be shared quickly amongst researchers — without any risk to the actual fossil and without having to travel hundreds or even thousands of miles to see the original.”
Co-author, Dr. Lindsay Zanno agrees: “Therizinosaurs , with their pot bellies and comically enlarged claws, are arguably the most bizarre theropod dinosaurs. We know a lot about their oddball skeletons from the neck down, but this is the first time we’ve been able to digitally dissect an entire skull.”
Note : The above story is based on materials provided by Society of Vertebrate Paleontology.
Fossil remains show the first amphibious ichthyosaur found in China by a team led by a UC Davis scientist. Its amphibious characteristics include large flippers and flexible wrists, essential for crawling on the ground. Credit: Ryosuke Motani/UC Davis
The first fossil of an amphibious ichthyosaur has been discovered in China by a team led by researchers at the University of California, Davis. The discovery is the first to link the dolphin-like ichthyosaur to its terrestrial ancestors, filling a gap in the fossil record. The fossil is described in a paper published in advance online Nov. 5 in the journal Nature.
The fossil represents a missing stage in the evolution of ichthyosaurs, marine reptiles from the Age of Dinosaurs about 250 million years ago. Until now, there were no fossils marking their transition from land to sea.
“But now we have this fossil showing the transition,” said lead author Ryosuke Motani, a professor in the UC Davis Department of Earth and Planetary Sciences. “There’s nothing that prevents it from coming onto land.”
Motani and his colleagues discovered the fossil in China’s Anhui Province. About 248 million years old, it is from the Triassic period and measures roughly 1.5 feet long.
Unlike ichthyosaurs fully adapted to life at sea, this one had unusually large, flexible flippers that likely allowed for seal-like movement on land. It had flexible wrists, which are essential for crawling on the ground. Most ichthyosaurs have long, beak-like snouts, but the amphibious fossil shows a nose as short as that of land reptiles.
Its body also contains thicker bones than previously-described ichthyosaurs. This is in keeping with the idea that most marine reptiles who transitioned from land first became heavier, for example with thicker bones, in order to swim through rough coastal waves before entering the deep sea.
The study’s implications go beyond evolutionary theory, Motani said. This animal lived about 4 million years after the worst mass extinction in Earth’s history, 252 million years ago. Scientists have wondered how long it took for animals and plants to recover after such destruction, particularly since the extinction was associated with global warming.
“This was analogous to what might happen if the world gets warmer and warmer,” Motani said. “How long did it take before the globe was good enough for predators like this to reappear? In that world, many things became extinct, but it started something new. These reptiles came out during this recovery.”
Reference:
Ryosuke Motani, Da-Yong Jiang, Guan-Bao Chen, Andrea Tintori, Olivier Rieppel, Cheng Ji, Jian-Dong Huang. A basal ichthyosauriform with a short snout from the Lower Triassic of China. Nature, 2014; DOI: 10.1038/nature13866
Note : The above story is based on materials provided by University of California – Davis.
Unexpectedly one of the largest diamond mines in Africa, Catoca in Angola, holds 118 million year old dinosaur, crocodile and large mammal tracks. The mammal tracks show a raccoon-sized animal, during a time when most were no larger than a rat.Nearly 70 distinct tracks were recovered in the Catoca mine in Angola. All the tracks were found in a small sedimentary basin, formed about 118 Ma, during the Early Cretaceous, in the crater of a kimberlite pipe.
Mammal tracks. (Photo by Marco Marzola)
The most important of these finds are those whose morphology is attributable to a large mammalian trackmaker, the size of a modern raccoon. There is no evidence from bones or teeth of such a large Early Cretaceous mammal from Africa or elsewhere in the World. The most comparably sized mammalian skeleton is known from China, and is 4-7 Ma older than the Angolan tracks. It has an estimated head-body length between 42 and 68 cm, but because it is missing hands and feet, a comparison with the tracks from Catoca is not possible.Nearby, 18 sauropod tracks were also found, with a preserved skin impression. These are the first dinosaur tracks found in Angola, and were discovered by the same paleontologist, Octávio Mateus, who found Angolatitan adamastor, the first Angolan dinosaur ever found, in 2005. Another trackway was attributed to a crocodilomorph trackmaker, a group that includes all modern crocodiles and extinct relatives, and has a unique laterally rotated handprint.
Mammal track. (Photo by Marco Marzola)
The tracks from Catoca represent the first fossils from the inlands of Angola ever found. The first mammal tracks were discovered in December, 2010 by the mine geologist Vladimir Pervov who contacted the paleontologist Octávio Mateus, who visited and collected the footprints in July 2011 and found the dinosaur tracks. For almost eight months, the Catoca Diamond Mine, fourth largest diamond mine in the World, stopped mining that sector, in order to preserve the findings and make the study possible. This work is part of the PaleoAngola Project, a scientific program of collaboration between various international institutions with the aim to research and promote vertebrate paleontology in Angola.
Note : The above story is based on materials provided by Society of Vertebrate Paleontology.
The eggs of amniotes — mammals, reptiles and birds — come in a remarkable variety of shapes and sizes.
Evolutionary biologists have now addressed shape variety in terrestrial vertebrates’ eggs, pinpointing morphological differences between the eggs of birds and those of their extinct relatives, the theropod dinosaurs.
Researchers from the University of Lincoln, UK, examined eggshell geometry from the transition of theropods — a sub-order of the Saurischian dinosaurs — into birds, based on fossil records and studies of their living species.
The results suggest that the early birds from the Mesozoic (252 to 66 million years’ ago) laid eggs that had different shapes to those of modern birds. This may suggest that egg physiology and embryonic development was different in the earliest birds and so this may have implications for how some birds survived the Cretaceous-Palaeocene extinction event that wiped out the dinosaurs.
Their findings are published in the journal Royal Society Open Science.
Author Dr Charles Deeming, from Lincoln’s School of Life Sciences, explained: “These results indicate that egg shape can be used to distinguish between different types of egg-laying vertebrates. More importantly they suggest Mesozoic bird eggs differ significantly from modern day bird eggs, but more recently extinct Cenozoic birds do not. This suggests that the range of egg shapes in modern birds had already been attained in the Cenozoic.”
The origin of the amniotic egg (an egg which can survive out of water) is one of the key adaptations underpinning vertebrates’ transition from sea to land more than 300 million years ago. Modern amniotic eggs vary considerably in shape and size and it is believed this variety may reflect the different patterns of egg formation and development in these taxa.
Dr Deeming added: “From a biological perspective, it is self-evident that different egg shapes by birds, both past and present, might be associated with different nesting behaviours or incubation methods. However, hardly any research has been carried out on this topic and fossil data are insufficient to draw firm conclusions. We hope that future discoveries of associated fossil eggs and skeletons will help refine the general conclusions of this work.”
Dr Deeming and co-author Dr Marcello Ruta, also from the University of Lincoln, are now investigating how the highly variable amounts of yolk and albumen (egg white) in eggs of different species could be a possible determinant of bird egg shape.
Reference:
D. Charles Deeming and Marcello Ruta. Egg shape changes at the theropod-bird transition, and a morphometric study of amniote eggs. Royal Society Open Science, 2014 DOI: 10.1098/rsos.140311
Note : The above story is based on materials provided by University of Lincoln.
Vintana Sertichi during the age of the dinosaurs. Credit: Illustration by Lucille Betti-Nash
A newly discovered 66-70 million-year-old groundhog-like creature, massive in size compared to other mammals of its era, provides new and important insights into early mammalian evolution. Stony Brook University paleontologist David Krause, PhD, led the research team that unexpectedly discovered a nearly complete cranium of the mammal, which lived alongside Late Cretaceous dinosaurs in Madagascar. The findings, which shake up current views on the mammalian evolutionary tree, will be published in the journal Nature on November 5.
“We know next to nothing about early mammalian evolution on the southern continents,” said Dr. Krause, a SUNY Distinguished Service Professor in the Department of Anatomical Sciences at Stony Brook. “This discovery, from a time and an area of the world that are very poorly sampled, underscores how very little we know. No paleontologist could have come close to predicting the odd mix of anatomical features that this cranium exhibits.”
The new fossil mammal is named Vintana sertichi. Vintana belongs to a group of early mammals known as gondwanatherians, which previously were known only from isolated teeth and a few scrappy jaw fragments. The well-preserved skull allows the first clear insight into the life habits and relationships of gondwanatherians.
“The discovery of Vintana will likely stir up the pot,” added Krause. “Including it in our analyses reshapes some major branches of the ‘family tree’ of early mammals, grouping gondwanatherians with other taxa that have been very difficult to place in the past.” The skull is huge, measuring almost five inches long, twice the size of the previously largest known mammalian skull from the entire Age of Dinosaurs of the southern supercontinent of Gondwana. At a time when the vast majority of mammals were shrew- or mouse-sized, living in the shadows of dinosaurs, Vintana was a super heavyweight, estimated to have had a body mass of about 20 pounds, twice or even three times the size of an adult groundhog. Adding to the intrigue is the fact that the cranium of Vintana has a peculiar shape, being very deep, with huge eye-sockets, and long, scimitar-shaped flanges for the attachment of massive chewing muscles.
The initial discovery was made in 2010 and, like many in science, came about by chance.
Vintana means luck and refers to the circumstances that its discoverer, Joseph Sertich, a former graduate student of Dr. Krause’s at Stony Brook University, had in finding the fossil in 2010. Sertich, now a curator at the Denver Museum of Nature & Science, collected a 150 block of sandstone filled with fish fossils. When the block was CT scanned in Stony Brook’s Department of Radiology the images revealed that something exceedingly rare lay inside — a nearly complete cranium of a previously unknown ancient mammal. The specimen represents only the third occurrence of mammalian skulls from the Cretaceous of the entire Southern Hemisphere, the other two being from Argentina.
“When we realized what was staring back at us on the computer screen, we were stunned,” said Joe Groenke, Krause’s technician and the first to view the CT images. Groenke spent the next six months extracting the skull from the surrounding rock matrix, one sand grain at a time.
Dr. Krause and his team conducted a comprehensive analysis of the skull, much of it using micro-computed tomography and scanning electron microscopy to reveal minute aspects of its anatomy, including areas like the braincase, nasal cavity, and inner ear that are poorly known in almost all early mammals. They compared the skull to those of hundreds of other fossil and extant mammals.
Various features of its teeth, eye sockets, nasal cavity, braincase, and inner ears revealed that Vintana was likely a large-eyed herbivore that was agile, with keen senses of hearing and smell. These and other features were also used to analyze its relationships to other early mammals. This phylogenetic analysis demonstrated that Vintana and other gondwanatherians were close relatives of multituberculates, the most successful mammalian contemporaries of dinosaurs on the northern continents. Gondwanatherians and multituberculates also grouped with another enigmatic taxon, the Haramiyida. The analysis by Krause’s team is the first to find strong evidence for clustering these three groups together, primarily because the cranial anatomy of gondwanatherians was previously completely unknown.
Dr. Krause emphasizes that a major question remains for scientists: How did such a peculiar creature evolve?
With its long-term isolation from the rest of the world, Madagascar had been an island for over 20 million years prior to the time in which the strata containing Vintana were deposited. Dr. Krause and his team theorize that the very primitive features of the cranium are holdovers from when the ancient lineage that ultimately produced Vintana was marooned on the island. It was this isolation, first from Africa, then Antarctica/Australia, and finally the Indian subcontinent, that allowed for the evolution of unique and bizarre features amidst Vintana’s primitive foundation of characteristics.
The research by Dr. Krause and colleagues on Vintana sertichi is supported by the National Science Foundation and the National Geographic Society.
Dr. Zhe-Xi Luo, a leading expert on early mammalian evolution from the University of Chicago, reviewed the manuscript for Nature. He hailed the Vintana as “the discovery of the decade for understanding the deep history of mammals; it offers the best case of how plate tectonics and biogeography have impacted animal evolution — a lineage of mammals isolated on a part of the ancient Gondwana had evolved some extraordinary features beyond our previous imagination. This new study of Vintana is a giant leap forward toward resolving the long-standing mystery of gondwanatherian mammals, which has puzzled paleontologists for decades.” Luo went on to say, “Vintana is also a galvanizing discovery for the future decades. With features so remarkably different from those of other mammals previously known to science, this fossil tells us how little we knew about the early evolution of mammals — it will stimulate paleontologists to conduct more field exploration in order to advance the frontier of deep time history and evolution.”
Dr. Guillermo Rougier from the University of Louisville, another expert who also reviewed the Nature paper, concurred, calling the study “a remarkable achievement” and predicted that the paper “will shake the field upon publication; the specimen is exceptional.”
“This is the first discovery of a cranial fossil from a very enigmatic extinct group of mammals called Gondwanatheria in the Southern Hemisphere,” says Dr. Yusheng (Chris) Liu, Program Director in the National Science Foundation (NSF)’s Division of Earth Sciences, which funded the research. “This important find will help us better understand the early evolution of gondwanatherians and their relatives.”
Video :
Reference:
David W. Krause, Simone Hoffmann, John R. Wible, E. Christopher Kirk, Julia A. Schultz, Wighart von Koenigswald, Joseph R. Groenke, James B. Rossie, Patrick M. O’Connor, Erik R. Seiffert, Elizabeth R. Dumont, Waymon L. Holloway, Raymond R. Rogers, Lydia J. Rahantarisoa, Addison D. Kemp, Haingoson Andriamialison. First cranial remains of a gondwanatherian mammal reveal remarkable mosaicism. Nature, 2014; DOI: 10.1038/nature13922
Note : The above story is based on materials provided by Stony Brook University.
Elk is a free geotechnical platform that can be extended with either free or/and commercial plugins. A single solution for all the phases of a geotechnical project: evaluate tests, model the subsoil, design structures.
Geotechnical object can be diplayed on any WMS map
Basic Earth shape management :
Areas
Points,
Placemarks,
Paths,
(…)
Some features :
Elk is a software platform : provides a structure that can be extended by plugins.
Structured data model : users manage one desktop, that could contain several workspaces, that could contain several projects,
Different kind of viewers : vertical viewer (depth), earth viewer (map), …
Data viewers can be added through plugins
Supports geoforge plugins (as GeoJSON or Gazetteer plugin)
Screenshots
Two displays are combined : vertical display with vertical interpretation and cartography display.Shallow foundation is displayed vertically and is geolocalized on a virtual earth.The parameters Em, Pf* and Pl* are obtained from the corrected test data
The fossil feather and skeleton of the iconic dinosaur Archaeopteryx. Credit: Museum für Naturkunde Berlin
Reconstructing ancient life has long required a certain degree of imagination. This is especially true when considering the coloration of long-extinct organisms. However, new methods of investigation are being incorporated into paleontology that may shed light (and color) on fossils. Research presented at the recent Society of Vertebrate Paleontology meeting shows the importance of using new imaging technologies in reconstructing the color of Archaeopteryx, one of the most famous and important fossils species.
Ryan Carney of Brown University incorporated scanning electron microscopy in a 2012 study to identify melanosomes (melanin-containing pigment structures) in modern feathers to reconstruct the feather color of the iconic Archaeopteryx, the so-called “missing link”—or more appropriately, evolutionary intermediate—between non-avian dinosaurs and birds. Archaeopteryx has also been referred to as the “Mona Lisa of paleontology,” a fossil taxon with great scientific, historical, and cultural importance.
However, after Carney’s original publication, there has been some recent controversy with respect to two competing papers that offer alternative interpretations. The first was that the Archaeopteryx feather was both black and white, based on the distribution of organic sulfur imaged via synchrotron. The second was that the fossilized microbodies in the feather represent bacteria instead of melanosomes, given their similarities in size and shape.
The results of Carney’s new research address these alternative interpretations and provide new insights into the Archaeopteryx feather. “The inner vane of the Archaeopteryx feather, which they claimed was white, we instead found to be packed with black melanosomes,” said Carney. “This is critical because white feather color is only produced in the absence of melanosomes.”
An image of the fossil feather, imprints of melanosomes (pigment structures), and reconstruction of the matte black feather. Credit: Museum für Naturkunde Berlin/Ryan Carney
Furthermore, Carney and his Swedish colleagues have investigated the preservation of melanosomes in a variety of other fossils, utilizing additional new analytical methods such as Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS). Carney added, “We are not contending that every fossilized microbody is a melanosome. However, this new chemical method has allowed us to detect actual melanin molecules, which are associated with the melanosome-like microbodies in fossilized feathers and skin, from both terrestrial and marine environments. This integrated structural and direct chemical evidence provides the definitive proof that melanosomes can indeed be preserved in the fossil record.”
Together, this new research paints the final picture of the famous wing feather as matte black with a darker tip, coloration that would have provided structural advantages to the plumage during this early evolutionary stage of dinosaur flight.
The application of such high-sensitivity analytical techniques is ushering in a new age of paleontological investigations. What once was artistic license, such as the appearance of ancient organisms, is now revealing itself in living color. As analytical methods in paleontology keep a pulse on technological advancements, we will continue to gain understanding of how fossil animals once lived and looked.
Note : The above story is based on materials provided by Society of Vertebrate Paleontology
Spinosaurus aegyptiacus was adapted for both land and water, and an exhibit featuring a life-sized model, based on new fossils unearthed in eastern Morocco, opens at the National Geographic Museum in Washington on Friday.
Dense layers of smog from forest fires and pollution frequently hang over the Sierra Nevada Mountains in California. Scientists are working to identify and describe the atmospheric particles forming these layers and how they interact to improve climate model projections and air quality prediction.
Untangling complex relationships requires understanding and facts. Applying both, Pacific Northwest National Laboratory led research finding the true culprits instigating layers of tiny atmospheric particles above California’s central valley. Contrary to previous assumptions, local recirculation patterns, affected by winds interacting with the unique topography of the Sierra Nevada Mountains, create these particle layers. Global model simulations had incorrectly tied the layers to a mix of long-range transport of pollution from Asia and local emissions of soot and particles from burning fossil fuels. This research improves understanding of how the particles impact the regional climate and policy makers’ decisions on how to regulate these emissions.
Atmospheric aerosols are tiny particles of soot and chemicals from combustion of fossil fuels and vapor from natural sources, such as trees and vegetation. Characterizing these particles and tracking them and their interactions in the atmosphere is a major challenge for air quality and climate models. Errors in aerosol predictions are a result of two sources of uncertainties: the emission rates from human-caused and natural sources; and simulations of the specific atmospheric processes that affect the lifecycle of these particles in models. Using direct observations and unique modeling tools, researchers can tackle both these challenges that affect projections of future heating and cooling of the Earth’s atmosphere.
Researchers from PNNL and their collaborators collected extensive meteorological, chemical, and aerosol measurement data at ground sites and aloft by research aircraft over a two-month period during two field investigations. The data from these campaigns were coupled with regional model simulations. This study integrated operational monitoring data and the wide range of meteorological, chemistry, and aerosol data collected between May and June of 2010 during the Carbonaceous Aerosol and Radiative Effects Study (CARES) and California Nexus of Air Quality and Climate Experiment (CalNex) field campaigns into a single publicly available data set as part of an “aerosol testbed.” The testbed was used to comprehensively evaluate the performance of one regional aerosol model, the Weather and Research Forecasting model coupled with chemistry (WRF-Chem), and understand how local and distant aerosol sources affect aerosol concentrations over California.
Their findings show that in global model simulations, the long-range transport of aerosols from Asia was overestimated, and anthropogenic emission rates of black carbon and other aerosol precursors over California were too high. Both of these factors can lead to erroneous estimates of how aerosols impact regional climate and decisions on how to regulate particulate emissions. The regional model also showed that observed aerosol layers above the central valley were not due to long-ranged transport as expected, but to local recirculation patterns associated with the interaction of the winds and topography of the Sierra Nevada that cannot be resolved by current climate models.
The unprecedented amount and type of measurements provided a unique dataset for modelers to test, evaluate, and improve the treatment of aerosol processes in regional and global models.
The CARES/CalNex testbed is being used to test and improve simulations of secondary organic aerosol formed by the atmospheric mixing of human-caused and natural-sourced trace gases. Scientists will also use the testbed to evaluate how the newly formed particles affect the size distribution measurement of all particles.
Reference:
Fast JD, J Allan, R Bahreini, J Craven, L Emmons, R Ferrare, PL Hayes, A Hodzic, J Holloway, C Hostetler, JL Jimenez, H Jonsson, S Liu, Y Liu, A Metcalf, A Middlebrook, J Nowak, M Pekour, A Perring, I Pollack, L Russell, T Ryerson, A Sedlacek, J Seinfeld, A Setyan, J Shilling, M Shrivastava, S Springston, C Song, R Subramanian, JW Taylor, V Vinoj, C Warneke, Q Yang, RA Zaveri, and Q Zhang. 2014. “Modeling Regional Aerosol Variability over California and Its Sensitivity to Emissions and Long-Range Transport during the 2010 CalNex and CARES Campaigns.” Atmospheric Chemistry and Physics 14:10013-10060. DOI: 10.5194/acp-14-10013-2014.
Note : The above story is based on materials provided by Pacific Northwest National Laboratory
Corné Kreemer, associate professor in the College of Science at the University of Nevada, Reno, conducts research on plate tectonics and geodetics. His latest research shows that oceanic tectonic plates deform due to cooling, causing shortening of the plates and mid-plate seismicity. Credit: Photo by Mike Wolterbeek, University of Nevada, Reno.
The puzzle pieces of tectonic plates that make up the outer layer of earth are not rigid and don’t fit together as nicely as we were taught in high school.
A study published in the journal Geology by Corné Kreemer, an associate professor at the University of Nevada, Reno, and his colleague Richard Gordon of Rice University, quantifies deformation of the Pacific plate and challenges the central approximation of the plate tectonic paradigm that plates are rigid.
Using large-scale numerical modeling as well as GPS velocities from the largest GPS data-processing center in the world — the Nevada Geodetic Laboratory at the University of Nevada, Reno — Kreemer and Gordon have showed that cooling of the lithosphere, the outermost layer of Earth, makes some sections of the Pacific plate contract horizontally at faster rates than other sections. This causes the plate to deform.
Gordon’s idea is that the plate cooling, which makes the ocean deeper, also affects horizontal movement and that there is shortening and deformation of the plates due to the cooling. In partnering with Kreemer, the two put their ideas and expertise together to show that the deformation could explain why some parts of the plate tectonic puzzle didn’t fall neatly into place in recent plate motion models, which is based on spreading rates along mid-oceanic ridges. Kreemer and Gordon also showed that there is a positive correlation between where the plate is predicted to deform and where intraplate earthquakes occur. Their work was supported by the National Science Foundation.
Results of the study suggest that plate-scale horizontal thermal contraction is significant, and that it may be partly released seismically. . The pair of researchers are, as the saying goes, rewriting the textbooks.
“This is plate tectonics 2.0, it revolutionizes the concepts of plate rigidity,” Kreemer, who teaches in the University’s College of Science, said. “We have shown that the Pacific plate deforms, that it is pliable. We are refining the plate tectonic theory and have come up with an explanation for mid-plate seismicity.”
The oceanic plates are shortening due to cooling, which causes relative motion inside the plate, Kreemer said. The oceanic crust of the Pacific plate off shore California is moving 2 mm to the south every year relative to the Pacific/Antarctic plate boundary.
“It may not sound like much, but it is significant considering that we can measure crustal motion with GPS within a fraction of a millimeter per year,” he said. “Unfortunately, all existing GPS stations on Pacific islands are in the old part of the plate that is not expected nor shown to deform. New measurements will be needed within the young parts of the plate to confirm this study’s predictions, either on very remote islands or through sensors on the ocean floor.”
This work is complementary to Kreemer’s ongoing effort to quantify the deformation in all of Earth’s plate boundary zones with GPS velocities — data that are for a large part processed in the Nevada Geodetic Laboratory. The main goal of the global modeling is to convert the strain rates to earthquake forecast maps.
“Because we don’t have GPS data in the right places of the Pacific plate, our prediction of how that plate deforms can supplement the strain rates I’ve estimated in parts of the world where we can quantify them with GPS data,” Kreemer said. “Ultimately, we hope to have a good estimate of strain rates everywhere so that the models not only forecast earthquakes for places like Reno and San Francisco, but also for places where you may expect them the least.”
Reference:
C. Kreemer, R. G. Gordon. Pacific plate deformation from horizontal thermal contraction. Geology, 2014; 42 (10): 847 DOI: 10.1130/G35874.1
Note : The above story is based on materials provided by University of Nevada, Reno. The original article was written by Mike Wolterbeek.
