Human Evolution Gap filled by 1.4 Million-Year-Old Fossil Human Hand Bone

December 21st, 2013 Riffin

Humans have a distinctive hand anatomy that allows them to make and use tools. Apes and other nonhuman primates do not have these distinctive anatomical features in their hands, and the point in time at which these features first appeared in human evolution is unknown. Now, a University of Missouri researcher and her international team of colleagues have found a new hand bone from a human ancestor who roamed the earth in East Africa approximately 1.42 million years ago. They suspect the bone belonged to the early human species, Homo erectus. The discovery of this bone is the earliest evidence of a modern human-like hand, indicating that this anatomical feature existed more than half a million years earlier than previously known.

“This bone is the third metacarpal in the hand, which connects to the middle finger. It was discovered at the ‘Kaitio’ site in West Turkana, Kenya,” said Carol Ward, professor of pathology and anatomical sciences at MU. The discovery was made by a West Turkana Paleo Project team, led by Ward’s colleague and co-author Fredrick Manthi of the National Museums of Kenya. “What makes this bone so distinct is that the presence of a styloid process, or projection of bone, at the end that connects to the wrist. Until now, this styloid process has been found only in us, Neandertals and other archaic humans.”

The styloid process helps the hand bone lock into the wrist bones, allowing for greater amounts of pressure to be applied to the wrist and hand from a grasping thumb and fingers. Ward and her colleagues note that a lack of the styloid process created challenges for apes and earlier humans when they attempted to make and use tools. This lack of a styloid process may have increased the chances of having arthritis earlier, Ward said.

The bone was found near sites where the earliest Acheulian tools have appeared. Acheulian tools are ancient, shaped stone tools that include stone hand axes more than 1.6 million years old. Being able to make such precise tools indicates that these early humans were almost certainly using their hands for many other complex tasks as well, Ward said.

“The styloid process reflects an increased dexterity that allowed early human species to use powerful yet precise grips when manipulating objects. This was something that their predecessors couldn’t do as well due to the lack of this styloid process and its associated anatomy,” Ward said. “With this discovery, we are closing the gap on the evolutionary history of the human hand. This may not be the first appearance of the modern human hand, but we believe that it is close to the origin, given that we do not see this anatomy in any human fossils older than 1.8 million years. Our specialized, dexterous hands have been with us for most of the evolutionary history of our genus, Homo. They are — and have been for almost 1.5 million years — fundamental to our survival.”

The styloid process is a projection of bone. Ward and her team found a styloid process at the end of a wrist bone more than 1.42 million years old, indicating this anatomical feature existed more than half a million years earlier than previously known. (Credit: University of Missouri)

The styloid process is a projection of bone. Ward and her team found a styloid process at the end of a wrist bone more than 1.42 million years old, indicating this anatomical feature existed more than half a million years earlier than previously known. (Credit: University of Missouri)

The study was published in the Proceedings of the National Academy of Sciences this week. Members of Ward’s team who helped discover and analyze the bone include: Matthew Tocheri, National Museum of Natural History in the Smithsonian Institution; J. Michael Plavcan, University of Arkansas; Francis Brown, University of Utah; and Fredrick Manthi, National Museums of Kenya.

The Mystery of Lizard Breath: One-Way Air Flow May Be 270 Million Years Old

December 17th, 2013 Riffin

Air flows mostly in a one-way loop through the lungs of monitor lizards — a breathing method shared by birds, alligators and presumably dinosaurs, according to a new University of Utah study.

The findings — published online Dec. 11 in the journal Nature — raise the possibility this breathing pattern originated 270 million years ago, about 20 million years earlier than previously believed and 100 million years before the first birds. Why remains a mystery.

“It appears to be much more common and ancient than anyone thought,” says C.G. Farmer, the study’s senior author and an associate professor of biology at the University of Utah. “It has been thought to be important for enabling birds to support strenuous activity, such as flight. We now know it’s not unique to birds. It shows our previous notions about the function of these one-way patterns of airflow are inadequate. They are found in animals besides those with fast metabolisms.”

The upper image is a colorized CT scan showing different airways in the lung of a monitor lizard. The bottom image shows how air flows in a mostly one-way loop through the lizard’s lung, as measured by sensors implanted as part of a University of Utah study. Note how the air flows through adjacent lateral airways (blue and purple) by moving through perforations in the airways’ walls. (Credit: Emma Schachner, University of Utah)

The upper image is a colorized CT scan showing different airways in the lung of a monitor lizard. The bottom image shows how air flows in a mostly one-way loop through the lizard’s lung, as measured by sensors implanted as part of a University of Utah study. Note how the air flows through adjacent lateral airways (blue and purple) by moving through perforations in the airways’ walls. (Credit: Emma Schachner, University of Utah)

But Farmer cautions that because lizard lungs have a different structure than bird and alligator lungs, it is also possible that one-way airflow evolved independently about 30 million years ago in the ancestors of monitor lizards and about 250 million years ago in the archosaurs, the group that gave rise to alligators, dinosaurs and birds. More lizard species, such as geckos and iguanas, must be studied to learn the answer, she says.

Farmer conducted the study with two University of Utah biologists — first author and postdoctoral fellow Emma Schachner and doctoral student Robert Cieri — and with James Butler, a Harvard University physiologist.

The research was funded by the American Association of Anatomists, the American Philosophical Society, the National Science Foundation and private donor Sharon Meyer.

Tidal Versus One-Way Airflow in the Lungs

Humans and most other animals have a “tidal” breathing pattern: Air flows into the lungs’ branching, progressively smaller airways or bronchi until dead-ending at small chambers called alveoli, where oxygen enters the blood and carbon dioxide leaves the blood and enters the lungs. Then the air flows back out the same way.

Birds, on the other hand, have some tidal airflow into and out of air sacs, but their breathing is dominated by one-way airflow in the lung itself. The air flows through the lung in one direction, making a loop before exiting the lung.

In 2010, Farmer published a study showing that a mostly one-way or “unidirectional” airflow controlled by aerodynamic valves exists in alligators. That means the breathing pattern likely evolved before 250 million years ago, when crocodilians — the ancestors of alligators and crocodiles — split from the archosaur family tree that led to the evolution of flying pterosaurs, dinosaurs and eventually birds.

The new study found a mostly one-way, looping air flow in African savannah monitor lizards, Varanus exanthematicus — one of roughly 73 species of monitor lizards — although there was some tidal airflow in regions of the lungs. That means one-way airflow may have arisen not among the early archosaurs about 250 million years ago, but as early as 270 million years ago among cold-blooded diapsids, which were the common, cold-blooded ancestors of the archosaurs and Lepidosauromorpha, a group of reptiles that today includes lizards, snakes and lizard-like creatures known as tuataras.

One-way airflow may help birds to fly without passing out at high altitudes, where oxygen levels are low. Before the new study, Farmer and others had speculated that the one-way airflow may have helped dinosaurs’ ancestors dominate the Earth when atmospheric oxygen levels were low after the Permian-Triassic mass extinction — the worst in Earth’s history — 251 million years ago.

“But if it evolved in a common ancestor 20 million years earlier, this unidirectional flow would have evolved under very high oxygen levels,” she says. “And so were are left with a deeper mystery on the evolutionary origin of one-way airflow.”

How the Study was Performed

As in her earlier research on alligators, Farmer and colleagues demonstrated predominantly one-way airflow in the lungs of monitor lizards in several ways. They performed CT scans and made 3-D images of lizard lungs to visualize the anatomy of the lungs. They surgically implanted flow meters in the bronchi of five monitor lizards to measure airflow direction.

Using lungs removed from 10 deceased lizards, the researchers measured air flow as they pumped air into and out of the lungs. They also pumped water laden with sunflower pollen particles or plastic microspheres through lizard lungs, and the movement of the pollen and spheres also showed the unidirectional airflow.

Savannah monitor lizards were used in the research because they are relatively large and thus easier to study, weighing about a pound and measuring roughly 15 inches from head to tail tip. Monitor lizards also have some of the highest rates of oxygen consumption, partly because they breathe using not only their trunk muscles and ribs, but also using “gular pumping,” which is when the lizards flare out their throat and pump air into their lungs.

Monitor lizards’ lungs have more than a dozen chambers or bronchi in each lung. The primary airway runs the length of the lung, with lateral bronchi branching off of it.

The study showed that air enters the lizard’s trachea or windpipe, then flows into the two primary airways, which enter the lung. But then, instead of flowing tidally back out the same way, the air instead loops back in a tail-to-head direction moving from one lateral airway to the next through small perforations between them.

The walls containing perforations that allow air to flow from one chamber to the next “are like lace curtains,” Farmer says.

There appear to be no mechanical valves or sphincters, so the one-way airflow appears “to arise simply from jetting,” or aerodynamic valves created when air flows around bends within the lung airways. That is supported by the fact that one-way airflow was observed even in lungs removed from dead lizards.

Location of Upwelling in Earth’s Mantle Discovered to Be Stable

December 16th, 2013 Riffin

A study published in Nature today shares the discovery that large-scale upwelling within Earth’s mantle mostly occurs in only two places: beneath Africa and the Central Pacific. More importantly, Clinton Conrad, Associate Professor of Geology at the University of Hawaii — Manoa’s School of Ocean and Earth Science and Technology (SOEST) and colleagues revealed that these upwelling locations have remained remarkably stable over geologic time, despite dramatic reconfigurations of tectonic plate motions and continental locations on the Earth’s surface. “For example,” said Conrad, “the Pangaea supercontinent formed and broke apart at the surface, but we think that the upwelling locations in the mantle have remained relatively constant despite this activity.”

This is a diagram showing a slice through the Earth's mantle, cutting across major mantle upwelling locations beneath Africa and the Pacific. (Credit: C. Conrad (UH SOEST))

This is a diagram showing a slice through the Earth’s mantle, cutting across major mantle upwelling locations beneath Africa and the Pacific. (Credit: C. Conrad (UH SOEST))

Conrad has studied patterns of tectonic plates throughout his career, and has long noticed that the plates were, on average, moving northward. “Knowing this,” explained Conrad, “I was curious if I could determine a single location in the Northern Hemisphere toward which all plates are converging, on average.” After locating this point in eastern Asia, Conrad then wondered if other special points on Earth could characterize plate tectonics. “With some mathematical work, I described the plate tectonic ‘quadrupole’, which defines two points of ‘net convergence’ and two points of ‘net divergence’ of tectonic plate motions.”

When the researchers computed the plate tectonic quadruople locations for present-day plate motions, they found that the net divergence locations were consistent with the African and central Pacific locations where scientists think that mantle upwellings are occurring today. “This observation was interesting and important, and it made sense,” said Conrad. “Next, we applied this formula to the time history of plate motions and plotted the points — I was astonished to see that the points have not moved over geologic time!” Because plate motions are merely the surface expression of the underlying dynamics of the Earth’s mantle, Conrad and his colleagues were able to infer that upwelling flow in the mantle must also remain stable over geologic time. “It was as if I was seeing the ‘ghosts’ of ancient mantle flow patterns, recorded in the geologic record of plate motions!”

Earth’s mantle dynamics govern many aspects of geologic change on the Earth’s surface. This recent discovery that mantle upwelling has remained stable and centered on two locations (beneath Africa and the Central Pacific) provides a framework for understanding how mantle dynamics can be linked to surface geology over geologic time. For example, the researchers can now estimate how individual continents have moved relative to these two upwelling locations. This allows them to tie specific events that are observed in the geologic record to the mantle forces that ultimately caused these events.

More broadly, this research opens up a big question for solid earth scientists: What processes cause these two mantle upwelling locations to remain stable within a complex and dynamically evolving system such as the mantle? One notable observation is that the lowermost mantle beneath Africa and the Central Pacific seems to be composed of rock assemblages that are different than the rest of the mantle. Is it possible that these two anomalous regions at the bottom of the mantle are somehow organizing flow patterns for the rest of the mantle? How?

“Answering such questions is important because geologic features such as ocean basins, mountains belts, earthquakes and volcanoes ultimately result from Earth’s interior dynamics,” Conrad described. “Thus, it is important to understand the time-dependent nature of our planet’s interior dynamics in order to better understand the geological forces that affect the planetary surface that is our home.”

The mantle flow framework that can be defined as a result of this study allows geophysicists to predict surface uplift and subsidence patterns as a function of time. These vertical motions of continents and seafloor cause both local and global changes in sea level. In the future, Conrad wants to use this new understanding of mantle flow patterns to predict changes in sea level over geologic time. By comparing these predictions to observations of sea level change, he hopes to develop new constraints on the influence of mantle dynamics on sea level.

Edmontosaurus:Dinosaur Fossil With Fleshy Rooster’s Comb Is First of Its Kind

December 15th, 2013 Riffin

The structure above the fossil’s head was so unexpected that Phil Bell put his chisel straight through the middle of it. “I was just expecting there to be rock, and all of a sudden there was skin underneath, and I thought to myself, ‘Whoops,'” he said. What Bell had found was the first dinosaur fossil with a fleshy crest atop its head.

“We know that lots of dinosaurs had different kinds of head ornaments, but these are all made of bones,” said Bell, a paleontologist at the University of New England, Australia. “There’s never been any indication that any dinosaurs had something like this, so this was totally out of left field,” he said.

Bell was studying a mummified specimen of Edmontosaurus regalis that had been found preserved in a single sandstone boulder in the Wapiti Formation in Alberta, Canada. E. regalis is a member of the hadrosaurids, or duck-billed dinosaurs, that were common around 75 to 65 million years ago. Researchers had previously described bony crests in many hadrosaurids.

But CT scans revealed that the new fossil’s crest was made entirely out of soft tissue, similar to a rooster’s comb. “This was a real surprise,” Bell said. “Not only did we have skin associated with the head, but also this completely bizarre structure.” The results were published in the December 12 issue of Current Biology.

David Evans, vertebrate paleontology curator at the Royal Ontario Museum in Toronto, who was not involved with the study, said he agreed with Bell’s interpretation of the new fossil. “We have a better idea of what skin looked like on Edmontosaurus than probably any other dinosaur, but we rarely had a look at skin on the head until now, and that’s what makes this discovery so exciting,” he said. “I don’t think we would have expected Edmontosaurus, which is a relatively plain, unornamented dinosaur, to have such a flashy soft-tissue crest, so that came as a bit of a surprise,” Evans said.

A rare, mummified specimen of the duck-billed dinosaur Edmontosauraus regalis shows for the first time that those dinosaurs' heads were adorned with a fleshy comb, most similar to the roosters' red crest.

A rare, mummified specimen of the duck-billed dinosaur Edmontosauraus regalis shows for the first time that those dinosaurs’ heads were adorned with a fleshy comb, most similar to the roosters’ red crest.

Best Crest Gets the Girl

“I think it reminds us that even in dinosaurs that we think we know well, new discoveries can really change what we think about how these animals looked and behaved,” Evans said. The new specimen was particularly exciting because it gave researchers a glimpse into the social lives of dinosaurs, he said.

The presence of bony crests, frills, and horns in many dinosaur groups has long indicated that dinosaurs were very likely visual animals, Evans said. “This is a rare glimpse of a soft-tissue display structure, and it gets us thinking that maybe soft-tissue structures were potentially just as important as hard-tissue ones in terms of socio-sexual displays,” he said.

According to both Bell and Evans, the fleshy comb’s prominent position on the head is similar to that found today in birds such as roosters, grouse, and condors, and it’s possible it could have served a similar function. “They use these to get the girls, basically—to indicate how fertile and how strong the male is,” Bell said. Edmontosaurus was a herding animal, so the fleshy structure could also have been used to indicate the top male within the herd, he said. “Perhaps the male with the biggest and brightest crest was the leader of the pack, so to speak,” Bell said.

Opening the Door to More Soft-Tissue Finds

Unlike bones, soft tissue and skin are rarely preserved in fossils. “For the skin to preserve, these animals had to be buried very rapidly, probably within a day or two after they died, and the chemical environment in the sediment was just right,” Bell said.

There have been a number of other similarly “mummified” dinosaurs, including of Edmontosaurus, but none of them have had similar soft tissues around the skull. The new fossil’s fleshy crest could indicate that such soft-tissue structures may have been more prevalent than previously believed.

“The actual bones of Edmontosaurus have absolutely no indication that there’s a crest of any sort in this animal, so similar crests or other fleshy structures could have been really widespread among dinosaurs,” Bell said. “The fact that we have no evidence on the bones apparently means nothing about the external appearance of these animals,” he said.

The discovery could make paleontologists look more carefully for such fleshy structures among fossils, Bell said. “Paleontologists are always in a rush to expose the bone, because that’s seen as the most exciting thing,” he said. “Fossilized skin is far more delicate than the bones. To actually leave the skin intact requires a lot of patience and a lot of very detailed work when you’re preparing the specimen,” Bell said.

“Now that we’re seeing that dinosaurs could do anything in terms of the way they looked, perhaps people will be more open-minded when they’re actually excavating, because that’s the moment of discovery,” Bell said. “Feathered dinosaurs from China are a prime example. Before, those kinds of structures were overlooked, but once people recognized what they were actually looking at, that these were feathers, they started appearing all over the world,” he said.

(Related: “Pictures: Dinosaur’s Flashy Feathers Revealed.”)

The Royal Ontario Museum’s Evans said the new Edmontosaurus specimen emphasizes how important the soft-tissue anatomy can be for understanding the biology of extinct animals, as well as how they looked when they were alive. “A discovery like this makes you think about what else we’re not seeing in the fossil record. It kind of opens the door for even more bizarre dinosaur anatomies than we typically think of,” he said.

Source: nationalgeographic

Runaway Process Drives Intermediate-Depth Earthquakes

December 14th, 2013 Riffin

Stanford researchers have uncovered a vital clue about the mechanism behind a type of earthquake that originates deep within Earth and accounts for a quarter of all temblors worldwide, some of which are strong enough to pose a safety hazard.

Stanford scientists may have solved the mystery of what drives a type of earthquake that occurs deep within Earth and accounts for one in four quakes worldwide.

A 3D rendering of the tectonic plates (multicolored regions) in northern South America (coastline shown in yellow) shows the underlying Bucaramanga Nest, which experiences more intermediate-depth earthquakes than any place in the world. (Credit: Image courtesy of German Prieto)

A 3D rendering of the tectonic plates (multicolored regions) in northern South America (coastline shown in yellow) shows the underlying Bucaramanga Nest, which experiences more intermediate-depth earthquakes than any place in the world. (Credit: Image courtesy of German Prieto)

Known as intermediate-depth earthquakes, these temblors originate farther down inside Earth than shallow earthquakes, which take place in the uppermost layer of Earth’s surface, called the crust. The kinds of quakes that afflict California and most other places in the world are shallow earthquakes.

“Intermediate-depth earthquakes occur at depths of about 30 miles down to about 190 miles,” said Greg Beroza, a professor of geophysics at Stanford and a coauthor of a new study that will be published in an upcoming issue of the journal Geophysical Research Letters.

Unlike shallow earthquakes, the cause of intermediate quakes is not well-understood. Part of the problem is that the mechanism for shallow earthquakes should not physically work for quakes at greater depths.

“Shallow earthquakes occur when stress building up at faults overcomes friction, resulting in sudden slip and energy release,” Beroza said. “That mechanism shouldn’t work at the higher pressures and temperatures at which intermediate depth earthquakes occur.”

A better understanding of intermediate-depth quakes could help scientists forecast where they will occur and the risk they pose to buildings and people.

“They represent 25 percent of the catalog of earthquakes, and some of them are large enough to produce damage and deaths,” said study first author Germán Prieto, an assistant professor of geophysics at the Massachusetts Institute of Technology.

A tale of two theories

There are two main hypotheses for what may be driving intermediate depth earthquakes. According to one idea, water is squeezed out of rock pores at extreme depths and the liquid acts like a lubricant to facilitate fault sliding. This fits with the finding that intermediate quakes generally occur at sites where one tectonic plate is sliding, or subducting, beneath another.

“Typically, subduction involves oceanic plates whose rocks contain lots of water,” Beroza said.

A competing idea is that as rocks at extreme depths deform, they generate heat due to friction. The heated rocks become more malleable, or plastic, and as a result slide more easily against each other. This can create a positive feedback loop that further weakens the rock and increases the likelihood of fault slippage.

“It’s a runaway process in which the increasing heat generates more slip, and more slip generates more heat and so on,” Prieto said.

To distinguish between the two possible mechanisms, the scientists studied a site near the city of Bucaramanga in Colombia that boasts the highest concentration of intermediate quakes in the world. About 18 intermediate depth temblors rattle Bucaramanga every day. Most are magnitude 2 to 3, weak quakes that are detectable only by sensitive instruments.

But about once a month one occurs that is magnitude 5 or greater — strong enough to be felt by the city’s residents. Moreover, past studies have revealed that most of the quakes appear to be concentrated at a site located about 90 miles beneath Earth’s surface that scientists call the Bucaramanga Nest.

A natural laboratory

This type of clustering is highly unusual and makes the Bucaramanga Nest a “natural laboratory” for studying intermediate depth earthquakes. Comparison studies of intermediate quakes from different parts of the world are difficult because the makeup of Earth’s crust and mantle can vary widely by location.

In the Bucaramanga Nest, however, the intermediate quakes are so closely packed together that for the purposes of scientific studies and computer models, it’s as if they all occurred at the same spot. This vastly simplifies calculations, Beroza said.

“When comparing a magnitude 2 and a magnitude 5 intermediate depth earthquake that are far apart, you have to model everything, including differences in the makeup of the Earth’s surface,” he said. “But if they’re close together, you can assume that the seismic waves of both quakes suffered the same distortions as they traveled toward the Earth’s surface.”

By studying seismic waves picked up by digital seismometers installed on Earth’s surface above the Bucaramanga Nest, the scientists were able to measure two key parameters of the intermediate quakes happening deep underground.

One, called the stress drop, allowed the team to estimate the total amount of energy released during the fault slips that caused the earthquakes. The other was radiated energy, which is a measure of how much of the energy generated by the fault slip is actually converted to seismic waves that propagate through Earth to shake the surface.

Two things immediately stood out to the researchers. One was that the stress drop for intermediate quakes increased along with their magnitudes. That is, larger intermediate quakes released proportionally more total energy than smaller ones. Second, the amount of radiated energy released by intermediate earthquakes accounted for only a tiny portion of the total energy as calculated by the stress drop.

“For these intermediate-depth earthquakes in Colombia, the amount of energy converted to seismic waves is only a small fraction of the total energy,” Beroza said.

The implication is that intermediate earthquakes are expending most of their energy locally, likely in the form of heat.

“This is compelling evidence for a thermal runaway failure mechanism for intermediate earthquakes, in which a slipping fault generates heat. That allows for more slip and even more heat, and a positive feedback loop is created,” said study coauthor Sarah Barrett, a Stanford graduate student in Beroza’s research group.

Source: Stanford University (2013, December 11). Runaway process drives intermediate-depth earthquakes. ScienceDaily.

Tooth Structure and Wear Provide Clues to Ecology and Evolution of Ancient Marine Creatures

December 13th, 2013 Riffin

A trio of published studies have highlighted the importance of examining dental structure and wear in ancient creatures to better understand their ecology and evolution.

New York Institute of Technology College of Osteopathic Medicine Assistant Professor Brian Beatty, Ph.D., contributed to all three of the studies with his expertise in analyzing patterns of tooth wear and structure.

“Tooth wear is a permanent record — it shows the interaction of the animal and the world,” says Beatty, a paleontologist who teaches anatomy to more than 300 medical and health professions students. “By examining the adult structure of teeth, we can learn how different vertebrate groups have been able to modify aspects of their tooth development so they can achieve structures that serve functional purposes.”

Beatty says the findings in the three papers he contributed to may change perceptions of how some marine creatures lived in ancient times.

In the Zoological Journal of the Linnean Society, Beatty and colleagues from Brazil, Edinburgh, Scotland, snd the Museum of Jurassic Marine Life in Dorset, England, described a new species of ancient crocodile that had uniquely large sets of two different types of jaw muscles, enabling it catch and kill prey quickly with both speed and power. The study’s first author is Mark Young from the University of Edinburgh’s School of Geosciences.

Torvoneustes, the "savage swimmer" ancient crocodile had enlarged jaws closing muscles attached to both the roof of the mouth and the roof of the skull. (Credit: Dmitry Bogdanov)

Torvoneustes, the “savage swimmer” ancient crocodile had enlarged jaws closing muscles attached to both the roof of the mouth and the roof of the skull. (Credit: Dmitry Bogdanov)

Beatty also found that the skull of the dolphin-like species known as Torvoneustes (“savage swimmer”), was noticeably different than other creatures it is usually compared to. Most crocodiles have large bumps and pits in their skulls; Torvoneustes had a smooth skull that was lighter and reduced turbulence, which likely made it an agile swimmer, with movements more akin to a dolphin.

“These features we described could be another side of how extremely specialized these marine crocodiles were getting,” says Beatty.

In a paper published in the Netherlands Journal of Geosciences, Beatty and colleagues, including first author F.M. Holwerda, studied the teeth of a small lizard-like species known as mosasaur. The researchers found that the …-million-year-old creature had a different feeding pattern than that associated with most lizards. Rather than grabbing prey and swallowing it, this species was more likely a bottom feeder, feasting on hard-shelled crabs, clams, and sea urchins along sandy areas beneath the sea.

The third paper, published in Acta Palaeontologica Polonica, details the unique anatomy of the teeth of Teleosaurids, another group of crocodile-like marine creature that lived about 165 million years ago. Beatty and his colleagues, including first author Young, described new findings about “denticles” or tooth-like projections similar to serrated surfaces in their teeth and visible only through scanning electron microscopic analysis. Closer examinations of the teeth, he said, mean that the creature perhaps had a larger role in its ecosystem beyond “being a croc simply snapping at things,” Beatty said.

“The findings of the three papers confirm that the interactions of marine vertebrates in the past with each other and with their environment were just as complex as they are now,” says Beatty. “Superficial resemblances do not define an animal’s lifestyle — the beauty of evolution is this diversity and you see how natural selection drives evolution. There are situations where animals are deriving new organs, tissues, and molecules and they’re doing that to deal with problems posed by natural selection. ”

Beatty is one of six paleontologists in the College of Osteopathic Medicine’s Department of Anatomy. He and Associate Professor Matthew Mihlbachler launched the online Dental Microwear Image Library containing thousands of magnified images of tooth surfaces that other scientists can use to establish hypotheses about ecological conditions in prehistoric times.

Source:  New York Institute of Technology (2013, December 12). Tooth structure and wear provide clues to ecology and evolution of ancient marine creatures. ScienceDaily. Retrieved December 13, 2013, from http://www.sciencedaily.com­/releases/2013/12/131212132408.htm

Lithosphere Deformed And Fractured Under Indian Ocean Much Earlier Than Previously Thought

December 12th, 2013 Riffin

The discovery by Indian and British scientists that the Earth’s strong outer shell – the ‘lithosphere’ – within the central Indian Ocean began to deform and fracture 15.4–13.9 million years ago, much earlier than previously thought, impacts our understanding of the birth of the Himalayas and the strengthening of the Indian-Asian monsoon.

India and Asia collided around 50 million years ago as a result of plate tectonics – the large-scale movements of the lithosphere, which continue to this day. The new study, published in the scientific journal Geology, focuses on the tectonics-related deformation of the lithosphere below the central Indian Ocean.

The discovery by Indian and British scientists that the Earth's strong outer shell -- the 'lithosphere' -- within the central Indian Ocean began to deform and fracture 15.4--13.9 million years ago, much earlier than previously thought, impacts our understanding of the birth of the Himalayas and the strengthening of the Indian-Asian monsoon. (Credit: Image courtesy of National Oceanography Centre, Southampton)

The discovery by Indian and British scientists that the Earth’s strong outer shell — the ‘lithosphere’ — within the central Indian Ocean began to deform and fracture 15.4–13.9 million years ago, much earlier than previously thought, impacts our understanding of the birth of the Himalayas and the strengthening of the Indian-Asian monsoon. (Credit: Image courtesy of National Oceanography Centre, Southampton)

“Compression of the lithosphere has caused large-scale buckling and cracking,” says team member Professor Jon Bull of the University of Southampton’s School of Ocean and Earth Science based at the National Oceanography Centre; “The ocean floor has been systematically transformed into folds 100-300 kilometres long and 2,000-3,000 metres high, and there are also regularly spaced faults or fractures that are evident from seismic surveys and ocean drilling.”

The onset of this deformation marks the start of major geological uplift of the Himalayas and the Tibetan Plateau, some 4,000 km further to the north, due to stresses within the wider India-Asia area. Some studies indicate that it began around 8.0–7.5 million years ago, while others have indicated that it started before 8.0 million years ago, and perhaps much earlier.

This controversy has now been addressed by Professor Bull and his colleagues Dr Kolluru Krishna of the National Institute of Oceanography in India, and Dr Roger Scrutton of Edinburgh University. They have analysed seismic profiles of 293 faults in the accumulated sediments of the Bengal Fan. This is the world’s largest submarine fan, a delta-shaped accumulation of land-derived sediments covering the floor of the Bay of Bengal.

They demonstrate that deformation of the lithosphere within the central Indian Ocean started around 15.4–13.9 million years ago, much earlier than most previous estimates. This implies considerable Himalayan uplift before 8.0 million years ago, which is when many geologists believe that the strong seasonal winds of the India-Asia monsoon first started.

“However,” says Professor Bull, “the realisation that the onset of lithospheric deformation within the central Indian Ocean occurred much earlier fits in well with more recent evidence that the strengthening of the monsoon was linked to the early geological uplift of the Himalayas and Tibetan plateau up to 15-20 million years ago.”

Intensive deep-sea drilling within the Bengal Fan should provide better age estimates for the onset of deformation of the lithosphere in the central Indian Ocean and help settle the controversy.

The research was funded by India’s Council of Scientific and Industrial Research (CSIR), and the United Kingdom’s Royal Society and Natural Environment Research Council (NERC).

Western Indian Ocean Earthquake and Tsunami Hazard Potential Greater Than Previously Thought

December 11th, 2013 Riffin

Earthquakes similar in magnitude to the 2004 Sumatra earthquake could occur in an area beneath the Arabian Sea at the Makran subduction zone, according to recent research published in Geophysical Research Letters.

The research was carried out by scientists from the University of Southampton based at the National Oceanography Centre Southampton (NOCS), and the Pacific Geoscience Centre, Natural Resources Canada.

The study suggests that the risk from undersea earthquakes and associated tsunami in this area of the Western Indian Ocean — which could threaten the coastlines of Pakistan, Iran, Oman, India and potentially further afield — has been previously underestimated. The results highlight the need for further investigation of pre-historic earthquakes and should be fed into hazard assessment and planning for the region.

Subduction zones are areas where two of Earth’s tectonic plates collide and one is pushed beneath the other. When an earthquake occurs here, the seabed moves horizontally and vertically as the pressure is released, displacing large volumes of water that can result in a tsunami.

Makran map earthquakes. (Credit: Image courtesy of National Oceanography Centre)

Makran map earthquakes. (Credit: Image courtesy of National Oceanography Centre)

The Makran subduction zone has shown little earthquake activity since a magnitude 8.1 earthquake in 1945 and magnitude 7.3 in 1947. Because of its relatively low seismicity and limited recorded historic earthquakes it has often been considered incapable of generating major earthquakes.

Plate boundary faults at subduction zones are expected to be prone to rupture generating earthquakes at temperatures of between 150 and 450 °C. The scientists used this relationship to map out the area of the potential fault rupture zone beneath the Makran by calculating the temperatures where the plates meet. Larger fault rupture zones result in larger magnitude earthquakes.

“Thermal modelling suggests that the potential earthquake rupture zone extends a long way northward, to a width of up to 350 kilometres which is unusually wide relative to most other subduction zones,” says Gemma Smith, lead author and PhD student at University of Southampton School of Ocean and Earth Science, which is based at NOCS.

The team also found that the thickness of the sediment on the subducting plate could be a contributing factor to the magnitude of an earthquake and tsunami there.

“If the sediments between the plates are too weak then they might not be strong enough to allow the strain between the two plates to build up,” says Smith. “But here we see much thicker sediments than usual, which means the deeper sediments will be more compressed and warmer. The heat and pressure make the sediments stronger. This results in the shallowest part of the subduction zone fault being potentially capable of slipping during an earthquake.

“These combined factors mean the Makran subduction zone is potentially capable of producing major earthquakes, up to magnitude 8.7-9.2. Past assumptions may have significantly underestimated the earthquake and tsunami hazard in this region.”

Cockroaches Probably Cleaned Up after Dinosaurs

December 10th, 2013 Riffin

Dinosaurs undoubtedly produced huge quantities of excrements. But who cleaned up after them? Dung beetles and flies with rapid development were rare during most of the Mesozoic. Candidates for these duties are extinct cockroaches (Blattulidae), whose temporal range is associated with herbivorous dinosaurs. An opportunity to test this hypothesis arises from coprolites to some extent extruded from an immature cockroach preserved in the amber of Lebanon, studied using synchrotron X-ray microtomography. 1.06% of their volume is filled by particles of wood with smooth edges, in which size distribution directly supports their external pre-digestion. Because fungal pre-processing can be excluded based on the presence of large particles (combined with small total amount of wood) and absence of damages on wood, the likely source of wood are herbivore feces. Smaller particles were broken down biochemically in the cockroach hind gut, which indicates that the recent lignin-decomposing termite and cockroach endosymbionts might have been transferred to the cockroach gut upon feeding on dinosaur feces.

Dinosaur-age cockroach of the extinct family Blattulidae. show more (A – head to leg end length: 3.8 mm) with antennal sensory system (B, C) and five preserved coprolites (D – optical, E – surface rendering of numbered coprolites and dense particles based on the image stack from synchrotron X-ray microtomography; F – ST orthoslice with labelled boundaries and fragments). Lebanon amber 1094A-I. Scales 0,5 mm. doi:10.1371/journal.pone.0080560.g001

Dinosaur-age cockroach of the extinct family Blattulidae.
(A – head to leg end length: 3.8 mm) with antennal sensory system (B, C) and five preserved coprolites (D – optical, E – surface rendering of numbered coprolites and dense particles based on the image stack from synchrotron X-ray microtomography; F – ST orthoslice with labelled boundaries and fragments). Lebanon amber 1094A-I. Scales 0,5 mm.
doi:10.1371/journal.pone.0080560.g001

 

Dinosaur-age wood decomposing cockroach with coprolite and its ecological context. show more A) wood fragment no. 123 (coprolite no. 3), volume 23077 µm3 (TRC- parenchymatous tangential ray cells); B) Lebanese amber (Blattulidae 1094A-I), length (head to leg end): 3.8 mm; C) a virtual synchrotron section (~1.2 mm) through coprolite no. 3, wood particles are pale; D) percentual representation of volume of the respective wood particles; E) distribution analysis of simple particle count of 280 wood fragments present in all five coprolites plotted over the fragment size; F) Ratios of the Blattulidae and “Voltziablatta”- group – families that replaced each other during the Triassic (interrupted arrow) – to all cockroaches, plotted over the timescale (in Ma). The origin and extinction of dinosaurs are pointed with arrows. “N in %” means percentual representation of number of specimens, “spp in %” is a percentual representation of species. Original data. doi:10.1371/journal.pone.0080560.g002

Dinosaur-age wood decomposing cockroach with coprolite and its ecological context.
A) wood fragment no. 123 (coprolite no. 3), volume 23077 µm3 (TRC- parenchymatous tangential ray cells); B) Lebanese amber (Blattulidae 1094A-I), length (head to leg end): 3.8 mm; C) a virtual synchrotron section (~1.2 mm) through coprolite no. 3, wood particles are pale; D) percentual representation of volume of the respective wood particles; E) distribution analysis of simple particle count of 280 wood fragments present in all five coprolites plotted over the fragment size; F) Ratios of the Blattulidae and “Voltziablatta”- group – families that replaced each other during the Triassic (interrupted arrow) – to all cockroaches, plotted over the timescale (in Ma). The origin and extinction of dinosaurs are pointed with arrows. “N in %” means percentual representation of number of specimens, “spp in %” is a percentual representation of species. Original data.
doi:10.1371/journal.pone.0080560.g002

 

Citation: Vršanský P, van de Kamp T, Azar D, Prokin A, Vidlička L, et al. (2013) Cockroaches Probably Cleaned Up after Dinosaurs. PLoS ONE 8(12): e80560. doi:10.1371/journal.pone.0080560

Editor: Ulrich Joger, State Natural History Museum, Germany

Why beaks evolved in some theropod dinosaurs and what their function : New Study

December 9th, 2013 Riffin

Why beaks evolved in some theropod dinosaurs and what their function might have been is the subject of new research by an international team of palaeontologists published this week in PNAS (Proceedings of the National Academy of Sciences).

Beaks are a typical hallmark of modern birds and can be found in a huge variety of forms and shapes. However, it is less well known that keratin-covered beaks had already evolved in different groups of dinosaurs during the Cretaceous Period.

Employing high-resolution X-ray computed tomography (CT scanning) and computer simulations, Dr Stephan Lautenschlager and Dr Emily Rayfield of the University of Bristol with Dr Perle Altangerel (National University of Ulaanbaatar) and Professor Lawrence Witmer (Ohio University) used digital models to take a closer look at these dinosaur beaks.

Computer models of the skull of Erlikosaurus andrewsi without (left) and with keratinous beak (right); colour plots resulting from finite element analysis show the degree of deformation in the different skull configurations. (Credit: Image by Dr Stephan Lautenschlager)

Computer models of the skull of Erlikosaurus andrewsi without (left) and with keratinous beak (right); colour plots resulting from finite element analysis show the degree of deformation in the different skull configurations. (Credit: Image by Dr Stephan Lautenschlager)

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, and which shows evidence that part of its snout was covered by a keratinous beak.

This new study reveals that keratinous beaks played an important role in stabilizing the skeletal structure during feeding, making the skull less susceptible to bending and deformation.

Lead author Dr Stephan Lautenschlager of Bristol’s School of Earth Sciences said: “It has classically been assumed that beaks evolved to replace teeth and thus save weight, as a requirement for the evolution of flight. Our results, however, indicate that keratin beaks were in fact beneficial to enhance the stability of the skull during biting and feeding.”

Co-author Dr Emily Rayfield, Reader of Palaeobiology at Bristol said: “Using Finite Element Analysis, a computer modelling technique routinely used in engineering, we were able to deduce very accurately how bite and muscle forces affected the skull of Erlikosaurus during the feeding process. This further allowed us to identify the importance of soft-tissue structures, such as the keratinous beak, which are normally not preserved in fossils.”

Co-author Lawrence Witmer, Chang Professor of Paleontology at the Ohio University Heritage College of Osteopathic Medicine said: “Beaks evolved several times during the transitions from dinosaurs to modern birds, usually accompanied by the partial or complete loss of teeth and our study now shows that keratin-covered beaks represent a functional innovation during dinosaur evolution.”

This work was funded by a research fellowship to Stephan Lautenschlager from the German Volkswagen Foundation and grants from the National Science Foundation to Lawrence Witmer.

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