Lava erupting on sea floor linked to deep-carbon cycle

Scientists from the Smithsonian and the University of Rhode Island have found unsuspected linkages between the oxidation state of iron in volcanic rocks and variations in the chemistry of the deep Earth. Not only do the trends run counter to predictions from recent decades of study, they belie a role for carbon circulating in the deep Earth.The team’s research was published May 2 in Science Express.

Elizabeth Cottrell, lead author and research geologist at the Smithsonian’s National Museum of Natural History, and Katherine Kelley at the University of Rhode Island’s Graduate School of Oceanography measured the oxidation state of iron, which is the amount of iron that has a 3+ versus a 2+ electronic charge, in bits of magma that froze to a glass when they hit the freezing waters and crushing pressures of the sea floor. Due to the high precision afforded by the spectroscopic technique they used, the researchers found very subtle variations in the iron-oxidation state that had been overlooked by previous investigations.

Molten magma erupted onto the seafloor freezes to glass that contains clues to its origin in Earth's deep interior and ancient past (field of view ~1 cm). Volcanic glasses like this one may reveal a link between Earth's oxidation state and the deep carbon cycle. Credit: Glenn Macpherson and Tim Gooding

Molten magma erupted onto the seafloor freezes to glass that contains clues to its origin in Earth’s deep interior and ancient past (field of view ~1 cm). Volcanic glasses like this one may reveal a link between Earth’s oxidation state and the deep carbon cycle.
Credit: Glenn Macpherson and Tim Gooding

The variations correlate with what Cottrell described as the “fingerprints” of the deep Earth rocks that melted to produce the lavas — but not in the way previous researchers had predicted. The erupted lavas that have lower concentrations of 3+ iron also have higher concentrations of elements such as barium, thorium, rubidium and lanthanum, that concentrate in the lavas, rather than staying in their deep Earth home. More importantly, the oxidation state of iron also correlates with elements that became enriched in lavas long ago, and now, after billions of years, show elevated ratios of radiogenic isotopes. Because radiogenic isotopic ratios cannot be modified during rock melting and eruption, Cottrell called this “a dead ringer for the source of the melt itself.”

Carbon is one of the “geochemical goodies” that tends to become enriched in the lava when rocks melt. “Despite is importance to life on this planet, carbon is a really tricky element to get a handle on in melts from the deep Earth,” said Cottrell. “That is because carbon also volatilizes and is lost to the ocean waters such that it can’t easily be quantified in the lavas themselves. As humans we are very focused on what we see up here on the surface. Most people probably don’t recognize that the vast majority of carbon — the backbone of all life — is located in the deep Earth, below the surface — maybe even 90 percent of it.”

The rocks that the team analyzed that were reduced also showed a greater influence of having melted in the presence of carbon than those that were oxidized. “And this makes sense because for every atom of carbon present at depth it has to steal oxygen away from iron as it ascends toward the surface,” said Cottrell. This is because carbon is not associated with oxygen at depth, it exists on its own, like in the mineral diamond. But by the time carbon erupts in lava, it is surrounded by oxygen. In this way, concludes Cottrell, “carbon provides both a mechanism to reduce the iron and also a reasonable explanation for why these reduced lavas are enriched in ways we might expect from melting a carbon-bearing rock.”

Tricky take-off kept pterodactyls grounded

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.”

 

Pterosaur hunting is illustrated. - Illustration by Mark Witton

Pterosaur hunting is illustrated. – Illustration by Mark Witton

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.

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: This story has been adapted from a news release issued by the Society of Vertebrate Paleontology

Erosion may trigger earthquakes

Researchers from laboratories at Géosciences Rennes (CNRS/Université de Rennes 1)*, Géosciences Montpellier (CNRS/Université de Montpellier 2) and Institut de Physique du Globe de Paris (CNRS/IPGP/Université Paris Diderot), in collaboration with a scientist in Taiwan, have shown that surface processes, i.e. erosion and sedimentation, may trigger shallow earthquakes (less than five kilometers deep) and favor the rupture of large deep earthquakes up to the surface. Although plate tectonics was generally thought to be the only persistent mechanism able to influence fault activity, it appears that surface processes also increase stresses on active faults, such as those in Taiwan, one of the world’s most seismic regions.

The work is published in Nature Communications on 21 November 2014.

Over the last few decades, many studies have focused on the evolution of mountain range landscapes over geological time (1 to 100 million years). The aim is to better understand the dynamics and interactions between erosion, sedimentation and tectonic deformation processes. Recent work has shown that Earth’s surface can undergo major changes in just a few days, months or years, for instance during extreme events such as typhoons or high magnitude earthquakes. Such events cause many landslides and an increase in sedimentary transport into rivers, as was the case in 2009 when typhoon Morakot struck Taiwan, leading to abrupt erosion of landscapes. Such rapid changes to the shape of Earth’s surface alter the balance of forces at the site of deep active faults.

In Taiwan, where erosion and deformation rates are among the highest in the world, the researchers showed that erosion rates of the order of 0.1 to 20 millimeters per year can cause an increase of the order of 0.1 to 10 bar in stresses on faults located nearby. Such forces are probably enough to trigger shallow earthquakes (less than five kilometers deep) or to favor the rupture of deep earthquakes up to the surface, especially if they are amplified by extreme erosion events caused by typhoons and high magnitude earthquakes. The researchers have thus shown that plate tectonics is not the only persistent mechanism able to influence the activity of seismic faults, and that surface processes such as erosion and sedimentation can increase stresses on active faults sufficiently to cause shallow earthquakes.

Thanks to an analysis of the relationships between surface processes and active deformation of Earth in near real-time, this study provides new perspectives for understanding the mechanisms that trigger earthquakes.

*The Géosciences Rennes laboratory is part of the Observatoire des Sciences de l’Univers de Rennes.

Citation: CNRS. “Erosion may trigger earthquakes.” ScienceDaily. ScienceDaily, 21 November 2014. <www.sciencedaily.com/releases/2014/11/141121082911.htm>

Tectonic plates not rigid, deform horizontally in cooling process

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.

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.

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.

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.”

Fossil finds behind mall causing excitement

A dig site, in New Jersey, is yielding exciting finds: the fossils of animals believed killed around the same time the dinosaurs disappeared. Uncovering the mystery has taken a cast of thousands.

Behind a strip mall in southern New Jersey, paleontologists from Drexel University are traveling 65 million years into the past. This quarry could be the most significant fossil site in decades.

“We know all these animals died at the same time because their bones are still put together,” said Ken Lacovara, the professor leading the dig team.

Lacovara thinks those may be the fossils of thousands of animals that all died around the time a meteor struck and killed off 70 percent of life on earth.

 

If it turns out to be the case, the only window the world has to animals actually killed in that cataclysm, that wipes out the dinosaurs, and essentially makes the modern world as we know it, is in a pit behind a shopping mall in New Jersey.

Last summer, Lacovara made big news when he announced another discovery — the largest dinosaur in the world.

The dreadnaughtus was bigger than a Boeing 746 and weight 65 tons. Lacovara found it in the wilds of Patagonia in Argentina.

In the New Jersey quarry, the Drexel team has uncovered some amazing fossils over the past 12 years, including a predator the size of a bus, and a 7-foot-long thoracosaurus crocodile that once lived along the coast here.

But this site is special for another reason. For three years now, Lacovara has invited the public to come help dig for a day; 1,300 people have shown up to help.

The people are fascinated, looking almost like they are going to find what’s under the Christmas tree.

“Can you imagine when you’re a kid, when you find your first fossil?” said Lacovara. :That’s a transformational experience, it connects them for the first time in a tangible to the Earth’s ancient past. I think for many of these kids they are never going to forget that moment.

The hope is these kids find more than fossils. Lacovara wants them to discover a love for science.

“I am going to be a paleontologist when I grow up,” said Jordan Lane, who came with her mother and brother. “Because they’re so cool.”

Even with all the help, the team has literally just scratched the surface of what the quarry might reveal.

“If we were to excavate here five days a week we could process an acre in 10 years and this property is 65 acres, so we have about 650 years of work left to do,” said Lacovara. “Geologically, that’s no time at all.”

Which means there will be plenty of work awaiting all these future paleontologists.

Source: CBS News November 16, 2014

 

 

 

 

 

How the tortoise’s ribs got embedded in its shell……….

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.

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

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

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.”

First amphibious ichthyosaur discovered, filling evolutionary gap

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.

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

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

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.”

Ebola’s evolutionary roots more ancient than previously thought

A new study is helping to rewrite Ebola’s family history. The research shows that filoviruses — a family to which Ebola and its similarly lethal relative, Marburg, belong — are at least 16-23 million years old.

Filoviruses likely existed in the Miocene Epoch, and at that time, the evolutionary lines leading to Ebola and Marburg had already diverged, the study concludes.

The research was published in the journal PeerJ in September. It adds to scientists’ developing knowledge about known filoviruses, which experts once believed came into being some 10,000 years ago, coinciding with the rise of agriculture. The new study pushes back the family’s age to the time when great apes arose.

“Filoviruses are far more ancient than previously thought,” says lead researcher Derek Taylor, PhD, a University at Buffalo professor of biological sciences. “These things have been interacting with mammals for a long time, several million years.”

According to the PeerJ article, knowing more about Ebola and Marburg’s comparative evolution could “affect design of vaccines and programs that identify emerging pathogens.”

The research does not address the age of the modern-day Ebolavirus. Instead, it shows that Ebola and Marburg are each members of ancient evolutionary lines, and that these two viruses last shared a common ancestor sometime prior to 16-23 million years ago.

Clues in ‘fossil genes’

Taylor and co-author Jeremy Bruenn, UB professor of biological sciences, research viral “fossil genes” — chunks of genetic material that animals and other organisms acquire from viruses during infection.

In the new study, the authors report finding remnants of filovirus-like genes in various rodents. One fossil gene, called VP35, appeared in the same spot in the genomes of four different rodent species: two hamsters and two voles. This meant the material was likely acquired in or before the Miocene Epoch, prior to when these rodents evolved into distinct species some 16-23 million years ago.

In other words: It appears that the known filovirus family is at least as old as the common ancestor of hamsters and voles.

“These rodents have billions of base pairs in their genomes, so the odds of a viral gene inserting itself at the same position in different species at different times are very small,” Taylor says. “It’s likely that the insertion was present in the common ancestor of these rodents.”

The genetic material in the VP35 fossil was more closely related to Ebola than to Marburg, indicating that the lines leading to these viruses had already begun diverging from each other in the Miocene.

The new study builds on Taylor’s previous work with Bruenn and other biologists, which used viral fossil genes to estimate that the entire family of filoviruses was more than 10 million years old. However, those studies used fossil genes only distantly related to Ebola and Marburg, which prevented the researchers from drawing conclusions about the age of these two viral lines.

The current PeerJ publication fills this viral “fossil gap,” enabling the scientists to explore Ebola’s historical relationship with Marburg.

Possible relevance to disease prevention

The first Ebola outbreak in humans occurred in 1976, and scientists still know little about the virus’ history. The same dearth of information applies to Marburg, which was recognized in humans in 1967 and implicated in the death of a Ugandan health worker this month.

Understanding the virus’ ancient past could aid in disease prevention, Taylor says. He notes that if a researcher were trying to create a single vaccine effective against both Ebola and Marburg, it could be helpful to know that their evolutionary lineages diverged so long ago.

Knowing more about filoviruses in general could provide insight into which host species might serve as “reservoirs” that harbor undiscovered pathogens related to Ebola and Marburg, Taylor says.

“When they first started looking for reservoirs for Ebola, they were crashing through the rainforest, looking at everything — mammals, insects, other organisms,” Taylor says. “The more we know about the evolution of filovirus-host interactions, the more we can learn about who the players might be in the system.”

Taylor and Bruenn’s co-authors on the PeerJ study include UB students Matthew Ballinger, Laura Hanzly and Jack Zhan, all in the UB Department of Biological Sciences.

Kung fu stegosaur: Lethal fighters when necessary

Stegosaurs might be portrayed as lumbering plant eaters, but they were lethal fighters when necessary, according to paleontologists who have uncovered new evidence of a casualty of stegosaurian combat. The evidence is a fatal stab wound in the pubis bone of a predatory allosaur. The wound — in the conical shape of a stegosaur tail spike — would have required great dexterity to inflict and shows clear signs of having cut short the allosaur’s life.

The wound found in the allosaur fits well with what would result from a stegosaur striking under and upwards with its spiked tail. Fossil's of contemporaneous stegosaurs appear to have had unusually flexible and agile tails. Credit: Robert Bakker

The wound found in the allosaur fits well with what would result from a stegosaur striking under and upwards with its spiked tail. Fossil’s of contemporaneous stegosaurs appear to have had unusually flexible and agile tails.
Credit: Robert Bakker

“A massive infection ate away a baseball-sized sector of the bone,” reports Houston Museum of Natural Science paleontologist Robert Bakker and his colleagues, who present a poster on the discovery on Tuesday at the meeting of the Geological Society of America in Vancouver, B.C. “Probably this infection spread upwards into the soft tissue attached here, the thigh muscles and adjacent intestines and reproductive organs.” The lack of any signs of healing strongly suggests the allosaur died from the infection.

Similar wounds are seen in rodeo cowboys or horses when they are gored by longhorns, Bakker said. And since large herbivores — like longhorn cattle, rhinos and buffalo — today defend themselves with horns, it’s reasonable to assume spiky herbivorous dinos did the same. A big difference is that stegosaurs wielded their weapon on their tails rather than their heads. Skeletal evidence from fossil stegosaurs suggests their tails were more dextrous than most dinosaur tails.

“They have no locking joints, even in the tail,” Bakker explained. “Most dinosaur tails get stiffer towards the end.” But stegosaurs had massive muscles at the base of the tails, flexibility and fine muscle control all the way to the tail tip. “The joints of a stegosaur tail look like a monkey’s tail. They were built for 3-dimensional combat.”

In order to deliver the mortal wound to the allosaur, a stegosaur would have had to sweep its tail under the allosaur and twist the tail tip, because normally the spikes point outward and backward. That would have been well within the ability of a stegosaur, Bakker said.

The fighting style and skill of stegosaurs should come as no surprise to anyone familiar with the dinosaur battle scene in the 1940 Disney animated film Fantasia, said Bakker. That segment of the movie shows a beefed up allosaur attacking a stegosaur. The stegosaur delivers a number of well aimed tail blows at the predator, but loses the fight. The Fantasia stegosaur tail dexterity appears to be accurate, he said. But he questions the stegosaur’s loss in the end. “I think the stegosaur threw the fight,” he said. On the other hand, he points out stegosaurs had among the smallest brains for its body size of any large animal, ever.

WFS Dino Diary: Riojasaurus ‭(‬Rioja lizard‭)

Name: Riojasaurus ‭(‬Rioja lizard‭)‬.
Phonetic: Re-o-jah-sore-us.
Named By: Jose Fernando Bonaparte‭ ‬-‭ ‬1967.
Classification: Chordata,‭ ‬Reptilia,‭ ‬Dinosauria,‭ ‬Saurischia,‭ ‬Sauropodomorpha,‭ ‬Prosauropoda,‭ ‬Riojasauridae.
Species: R.‭ ‬incertus‭ (‬type‭)‬.
Diet: Herbivore.
Size: About‭ ‬10‭ ‬meters long.
Known locations: Argentina,‭ ‬La Rioja Province‭ ‬-‭ ‬Los Colorados Formation.
Time period: Norian of the Triassic.
Fossil representation: Several individuals.

       Riojasaurus was and still often is credited as being related to Melanorosaurus,‭ ‬though detailed study of the two genera does turn up some key differences.‭ ‬These two genera are both significant in the development of the prosauropods into the large sauropods common by the late Jurassic in that they are both large and postured so that they were probably obligatory quadrupedal.‭ ‬This is different from other more basal forms of prosauropod that are considered to have been optionally bipedal or quadrupedal,‭ ‬a hallmark of their ancestry from earlier saurischian dinosaurs that seem to have been primarily bipedal.
As a dinosaur,‭ ‬the teeth of Riojasaurus were leaf shaped and serrated hinting at a preference in eating lush leafy vegetation.‭ ‬The scleral rings of the eyes also reveal that Riojasaurus was a cathemeral dinosaur meaning that it was active for short periods during both the day and night.‭ ‬Although the rear limbs were slightly longer than the fore limbs,‭ ‬there was not as huge a difference between them as in some more basal form prosauropod genera,‭ ‬reinforcing the notion that Riojasaurus walked about upon all fours.
Other dinosaurs‭ ‬known from the Los Colorados Formation where Riojasaurus has been found include the‭ ‬sauropodomorphs Coloradisaurus and Lessemsaurus.‭ ‬The theropod Zupaysaurus is also present in a slightly later deposit,‭ ‬though if they did manage to overlap then this dinosaur may have been a predator of smaller juvenile Riojasaurus.

Riojasaurus ‭(‬Rioja lizard‭)

Riojasaurus ‭(‬Rioja lizard‭)

 

Further reading
-‭ ‬Dos nuevas‭ “‬faunas‭” ‬de reptiles triasicos de Argentina‭ [‬Two new reptilian‭ “‬faunas‭” ‬of the Argentine Triassic‭]‬,‭ ‬Jose F.‭ ‬Bonaparte‭ ‬-‭ ‬1967.

-‭ ‬Nocturnality in Dinosaurs Inferred from Scleral Ring and Orbit Morphology,‭ ‬Lars Schmitz‭ & ‬Ryosuke Motani‭ ‬-‭ ‬2011.

Courtesy: PreHistoric Wild life.Com