Dickinsonia costata, an extinct soft-bodied organism representing one of the first complex metazoans in the fossil record.Total length 53.5?mm. Credit: Scott Evans
Hundreds of millions of years before there was a chicken or an egg to debate, the first complex animals were evolving in parallel with Earth’s rising oxygen levels.
But what came first—animals or oxygen?
That question is the central theme of a special issue of Emerging Topics in Life Sciences published Sept. 28 by Portland Press. Titled “Early Earth and the Rise of Complex Life,” the issue was edited by UC Riverside’s Timothy Lyons, a distinguished professor of biogeochemistry, along with UCR professor Mary Droser and postdoctoral researcher Kimberly Lau, and Susannah Porter, a professor at UC Santa Barbara. Several of the 18 articles included in the collection were authored or co-authored by UCR researchers.
While geological and fossil records suggest the formation of complex life and oxygenation of the planet progressed hand-in-hand, the details about the possible cause-and-effect relationship are still murky and debated. Did rising oxygen levels in the oceans and atmosphere drive the formation of complex life, were they unrelated, or did the eventual emergence and proliferation of complex life instead cause a rise in oxygen?
“While those questions remain largely unanswered at this time, this curated collection offers an up-to-date look at the relationship between early organisms and their environments through the lens of a diverse group of scientists using a variety of cutting-edge methods,” Lyons said.
Oxygen began to accumulate in the oceans and atmosphere 2.3-2.4 billion years ago during the Great Oxidation Event. By 1.8 billion years ago, oxygen levels had fallen to intermediate levels, where they remained stable for another billion years—dubbed ‘the boring billion’ by scientists. Around 800 million years ago, the levels likely increased again, and the first animals evolved soon after.
A paper by Scott Evans, a graduate student in Droser’s lab, presents evidence suggesting another rise of oxygen catalyzed innovation in animal life. By studying fossil animals from between 550-560 million years ago, during the so-called Ediacaran era, Evans showed that Earth’s early animals, which were ocean-dwelling creatures that “breathed” by diffusion, evolved to be larger. This meant a lower fraction of their cells came in contact with the surrounding waters during a period of increased oxygen and became smaller again during a transient decrease.
“This relationship suggests that a rise in oxygen levels may have provided the environment necessary for the diversification of complex body plans and energetically demanding ecologies,” Lyons said.
Not everyone in the series agrees that a rise in oxygen was key to our early ancestors’ success. Daniel Mills at the University of Southern Denmark cautions the relationship between the evolution of complex life and increasing oxygenation remains open to question. Perhaps, he suggests, the emergence of animals might have been based on “internal developmental constraints,” meaning the time it took for animals with sophisticated cellular machinery governed by complex genetics to evolve independently of environmental changes.
“Readers will not leave this collection with a clear single answer,” Lyons said. “Instead, our goal was to give them an up-to-date view of the key debates about evolving early complex life and environmental change, the full context that lies behind the questions and uncertainties, and the work left to do.”
Reference:
Timothy W. Lyons et al, Early Earth and the rise of complex life, Emerging Topics in Life Sciences (2018). DOI: 10.1042/ETLS20180093
A team of researchers from The University of Western Australia and two Canadian universities has applied a first-of-its-kind technique that measures the long-term life cycle of sulphur, helping to explain the preferential location of high-value mineral deposits at the edges of ancient continents.
The study, published today in Nature Communications, charts the life cycle of sulphur over hundreds of millions of years, from its origins as a volcanic gas emitted into the primordial atmosphere and oceans, and all the way throughout its journey across the earth’s deep crust.
Sulphur plays a critical role in a variety of fundamental earth processes as it regulates the global climate, is essential to the living cell, and is the primary molecule necessary to transport and concentrate precious metals such as gold and platinum.
The team, which included researchers from Canada’s Université Laval and McGill University, initially set out to better understand the behaviour of sulphur in the ancient earth. During the process the researchers were able to create a technique using sophisticated technology based at UWA that could help explorers identify new mineral-rich provinces in Australia and around the world.
Co-author Associate Professor Marco Fiorentini, from UWA’s School of Earth Sciences, said that the largest and richest deposits of precious metals in Australia and on Earth were generally associated with large concentrations of sulphur-rich minerals.
“By understanding how and where sulphur is stored researchers can make predictions about the location of mineral deposits,” Professor Fiorentini said. “Just as a medical dye may be used to unveil the intricate pathways of the inner human body, we have developed a technique to illuminate the cryptic pathway of sulphur through the crust of our planet more than two billion years ago.”
The technique presents a new way to engage with the minerals industry, helping them to explore vast areas of the planet that may host valuable resources.
Reference:
Crystal LaFlamme et al. Atmospheric sulfur is recycled to the crystalline continental crust during supercontinent formation, Nature Communications (2018). DOI: 10.1038/s41467-018-06691-3
Eruption patterns in the Taupo Volcanic Zone provide insight into how super eruptions might work. Credit: Chad Deering/Michigan Tech
The road cut seems rather dull and gray at first, but the tuff and pumice rocks hold the secrets of a volcano. Covered in green ferns and brown roots, the rocks lock in the compositional and temporal signatures from past eruptions of the Taupo Volcanic Zone, New Zealand. Taupo is an active system, where some of the world’s largest eruptions have occurred over the past two million years. In particular, between 350,000 and 240,000 years ago, Taupo exploded with seven eruptions–a volcanic ‘flare-up’ of activity.
But why? A team of geoscientists went to New Zealand’s North Island to dig into the answers and the white-gray rocks holding them. As explained in their findings, published this week in Science Advances, the team found that the flare-up of eruptions showed a pattern: The underlying magma body would erupt and reset over only decades to centuries in progressively shallower chambers close to the Earth’s surface.
A better understanding of what governs this pattern can help with understanding supereruptions, which may be mitigated by smaller and more frequent eruptions. In addition, these results could aid with predictions of similar type eruptions through improved modeling down the road. Vanderbilt University geoscientists led the team along with Michigan Technological University, University of Canterbury, Brown University, Princeton University, University of Lausanne, OFM Research-West and Woods Hole Oceanographic Institution. Chad Deering, an assistant professor of geology at Michigan Tech, studied the Taupo Volcanic Zone for his PhD and continues to do fieldwork in the area.
“This massive outpouring of magma essentially drains the magmatic system over a relatively short period of time,” Deering says. “However, following this activity, new magma rapidly ascends within the crust and primes it at shallow depths only to feed more large eruptions.”
The magma climbs the crustal ladder, so to speak, as it lodges in shallower and shallower chambers before erupting. The crust then warms and weakens, melting more of the surrounding crust, which enriches the magma with new minerals and water–a recipe for explosion.
The question that remains is: How long did it take for these crystal-rich magma bodies to assemble between eruptions? The study’s lead researcher, Guilherme Gualda of Vanderbilt University, says it could be thousands of years, but may be even shorter.
“You have magma sitting there that’s crystal-poor/melt-rich for a few decades, maybe 100 years, and then it erupts,” Gualda said. “Then another magma body is established, but we don’t know how gradually that body assembles. It’s a period in which you’re increasing the amount of melt in the crust.”
It all comes down to timing. And better understanding the timeline and chemical make-up of the Taupo Volcanic Zone in New Zealand gives insight into how supereruptions build up in volcanoes around the world.
Reference:
Climbing the crustal ladder: Magma storage-depth evolution during a volcanic flare-up. DOI: 10.1126/sciadv.aap7567
Palaeontologist Jonah Choiniere says a student noticed a ‘few (fossilised) bones coming out’ of a massive rock on a remote farm in central South Africa. ‘It turned out to be a hip of a species we’ve never seen before’
The sun rises over the South African bush as scientists laden with backpacks climb a hillside.
They get down to work, carving into two immense blocks of stone that have concealed the secrets of an ancestor of modern-day crocodiles for some 200 million years.
Jonah Choiniere and his team from Johannesburg’s Witwatersrand University had tracked the reptile from another age for three years.
The search brought them to a stretch of farmland in the central town of Rosendal, where they are surrounded by cattle and impalas.
“In 2015, one of my students just saw a few (fossilised) bones coming out,” said Choiniere, his shirt sticking to sweat from the morning’s hike.
“We started to excavate it and we brought it back to the lab and it turned out to be a hip of a species we’ve never seen before,” said the palaeontologist, who is originally from the United States.
The delicate excavation process at the site is grindingly slow and continues today.
Before being extracted, the stone surrounding a fossil is carefully enveloped in a protective layer of plaster.
After five hours of drying time, the stone is chiselled free, lifted by three strong people, and then transported by road nearly 300 kilometres (185 miles) to Johannesburg into the expert hands of Wilfred Bilankulu.
“My job is to make the fossils visible,” said the former fine arts student. “I’m taking off the jacket that has been put in place around the fossil, and after I prepare them using dental tools.”
Rare specimen
The herculean task will take between eight and 12 months. A similar amount of time will be needed to meticulously examine, compare and describe the find.
Choiniere expected a bountiful haul even before he had the discovery in hand.
“This is a pretty good harvest for us. We didn’t know what to expect when we came into this quarry… I can say it’s much better than what we were expecting, very promising,” he said.
Given the bones already uncovered, Choiniere’s research student Rick Tolchard can barely hide his excitement.
He knows he is in the presence of a rare specimen, the improbable forefather of the crocodile family which today stalks African waterways.
“Two hundred and fifty to 200 million years ago, these animals were the dominant land carnivores and they were found all over the world… (but) in South Africa we don’t have a record of them,” he said.
“Some of them were, I imagine, sort of like a crocodile crossed with a lion, a very large quadrupedal, legs under the body, with these massive big jaws—a very intimidating animal.
“The one here would have stood on his hind legs, it would have looked more like a theropod dinosaur, almost like a raptor.”
In recent years, South Africa has become a top destination for dinosaur hunters.
Just an hour’s drive from the Rosendal farm, Choiniere’s team has already unearthed fossils belonging to a newly discovered type of dinosaur that roamed the earth 200 million years ago.
‘Giant thunderclap at dawn’
Measuring four metres (13 feet) to the shoulder and weighing 12 tonnes—twice the weight of a modern elephant—the giant herbivore known in the local Sesotho language as Ledumahadi mafube (“a giant thunderclap at dawn”) shook up the family tree of extinct monsters.
Choiniere said it could well be “the first of the true giants”.
The beast is a forerunner of the 60-tonne sauropods familiar from Steven Spielberg’s blockbuster “Jurassic Park” series.
Experts say the southern tip of Africa is an ideal place to study the transition between the Triassic and Jurassic periods, when mass extinction events shaped the evolution of the planet.
“One of the reasons is that about 66 percent of the surface of South Africa has fossils on it—there are a lot of fossil-bearing areas,” Choiniere said.
“We don’t get much rainfall, especially in the interior, so we have areas that erode rapidly—and that erosion exposes fossils.”
“It’s phenomenal, it’s really great,” said palaeontology masters candidate Cebisa Mdekazi, a young student flying the flag for the next generation of South African palaeontologists.
“It also instills pride for your country—you have all those amazing things in our country, and we can show the world.”
Her professor, Choiniere, is far from finished with South Africa.
“Every time we go out into the field and we dig something up, there’s a pretty good chance that it might be something new,” Mdekazi said.
“It’s dinosaur country, and there’s no way we’ll ever finish the work in my lifetime.”
Note: The above post is reprinted from materials provided by AFP.
Seismogram being recorded by a seismograph at the Weston Observatory in Massachusetts, USA. Credit: Wikipedia
A Canadian fault scientists thought was inactive may actually be capable of producing large-magnitude earthquakes, a new study finds. The results suggest residents of British Columbia on Canada’s west coast have a higher risk of experiencing a damaging earthquake than previously thought, according to the study’s authors.
The Leech River fault, which extends across the southern tip of Vancouver Island, is part of the Cascadia Subduction Zone, where scientists think there is about a 40 percent chance a megathrust earthquake of 9.0 or more magnitude could occur in the next 50 years, according to the Oregon Office of Emergency Management. Scientists thought the Leech River fault itself was inactive, but the new study shows it produced three surface-rupturing earthquakes in the last 10,000 years with a magnitude greater than 6.5 and is still capable of producing large earthquakes.
The results suggest the part of the Cascadia Subduction Zone running through Canada could contain additional potentially dangerous active faults scientists aren’t even aware of yet, according to Kristin Morell, an assistant professor of Earth science at the University of California Santa Barbara and previously at the University of Victoria. Morell is lead author of the new study in Geophysical Research Letters, a journal of the American Geophysical Union.
Morell herself lived on the Leech River fault, which runs from Sombrio Beach through Royal Roads University and offshore of downtown Victoria. She published initial evidence for earthquake surface ruptures along the fault in 2017.
“Even though the fault had not shown any detectable seismic activity for thousands of years and was believed to be inactive, I had a strong suspicion that it could produce damaging surface rupturing earthquakes because it appears to connect with the Devil’s Mountain fault,” Morell said. The Devils Mountain fault has been found to be capable of causing a magnitude-7.5 earthquake off Victoria in United States Geological Survey scenarios.
In the new study, Morell and her team constructed a surface rupture history of the Leech River fault using data collected with a LiDAR (Light Detection and Ranging) system, which maps the Earth’s terrestrial surface by sending laser pulses from an aircraft, and paleoseismic trenching, which involves digging across the face of a fault to look for evidence of past surface rupture.
In addition to revealing a history of surface-rupturing earthquakes produced by the Leech River fault, the study also showed that in the past, rocks on either side of the fault moved vertically with respect to each other, even though other evidence says the fault should behave more like the San Andreas strike slip fault, where two blocks of rock slide past one another laterally.
Morell and her team said they don’t yet know why the Leech River fault moves differently from what they would have anticipated, but the new finding helps scientists understand how all the faults in the region fit together to accommodate the build-up of stresses within the earth, and how the fault will behave in the long term.
The new study also provides direct dating of earthquakes on this kind of fault, making it possible for scientists to calculate the slip rate per year, which is used in seismic hazard models for building and safety codes. These codes need to be updated to reflect how the Earth is moving near densely populated areas and how movement will affect the infrastructure and people living there, according to Morell.
Neither the rate nor the direction of movement of the fault could have been known without paleoseismic trenching and LiDAR technology. The technology is expensive, but without it it’s impossible to know what’s underneath 60 million hectares of trees, which cover close to two-thirds of the province of British Columbia, Morell said.
As a field geologist, Morell has a unique perspective on what it means to be aware of the environment, and our place in it as humans.
“I think it’s important for all of us to understand our surroundings and the landscape that we are a part of,” said Morell. “All of us as a society should have a grasp on the larger time scale of the Earth, where events leading up to the catastrophes we see in our lifetimes occur over millions of years.”
Reference:
K. D. Morell et al. Holocene surface rupture history of an active forearc fault redefines seismic hazard in southwestern British Columbia, Canada, Geophysical Research Letters (2018). DOI: 10.1029/2018GL078711
A new study by researchers at The Australian National University (ANU) could help us understand how our planet was formed.
Associate Professor Hrvoje Tkalčić and PhD Scholar Than-Son Phạm are confident they now have direct proof that Earth’s inner core is solid.
They came up with a way to detect shear waves, or “J waves” in the inner core — a type of wave which can only travel through solid objects.
“We found the inner core is indeed solid, but we also found that it’s softer than previously thought,” Associate Professor Tkalčić said.
“It turns out — if our results are correct — the inner core shares some similar elastic properties with gold and platinum. The inner core is like a time capsule, if we understand it we’ll understand how the planet was formed, and how it evolves.”
Inner core shear waves are so tiny and feeble they can’t be observed directly. In fact, detecting them has been considered the “Holy Grail” of global seismology since scientists first predicted the inner core was solid in the 1930s and 40s.
So the researchers had to come up with a creative approach.
Their so-called correlation wavefield method looks at the similarities between the signals at two receivers after a major earthquake, rather than the direct wave arrivals. A similar technique has been used by the same team to measure the thickness of the ice in Antarctica.
“We’re throwing away the first three hours of the seismogram and what we’re looking at is between three and 10 hours after a large earthquake happens. We want to get rid of the big signals,” Dr Tkalčic said.
“Using a global network of stations, we take every single receiver pair and every single large earthquake — that’s many combinations — and we measure the similarity between the seismograms. That’s called cross correlation, or the measure of similarity. From those similarities we construct a global correlogram — a sort of fingerprint of the Earth.”
The study shows these results can then be used to demonstrate the existence of J waves and infer the shear wave speed in the inner core.
While this specific information about shear waves is important, Dr Tkalčić says what this research tells us about the inner core is even more exciting.
“For instance we don’t know yet what the exact temperature of the inner core is, what the age of the inner core is, or how quickly it solidifies, but with these new advances in global seismology, we are slowly getting there.
“The understanding of the Earth’s inner core has direct consequences for the generation and maintenance of the geomagnetic field, and without that geomagnetic field there would be no life on the Earth’s surface.”
The research has been published in the journal Science.
Reference:
Hrvoje Tkalčić, Thanh-Son Phạm. Shear properties of Earth’s inner core constrained by a detection of J waves in global correlation wavefield. Science, 2018; 362 (6412): 329 DOI: 10.1126/science.aau7649
The island of Daphne to the north of Santa Cruz as seen from an aircraft approaching Baltra Airport. This island consists of a volcanic crater rising 120 meters above sea level. Credit: Yamirka Rojas-Agramonte
The Galapagos archipelago is one of the most famous groups of islands in the world. Many of the animal and plant species are unique because of the islands’ isolated location in the Pacific, 1,000 kilometers off of the coast of Ecuador. Thanks to a recently-signed special cooperation agreement, geoscientists based at Johannes Gutenberg University Mainz (JGU) in Germany will have the opportunity in coming years to research the geological development of the Galapagos Islands. An unusual mineral has recently been discovered that raises far-reaching questions about the composition of the magma source from which these oceanic islands were formed.
The idea for the collaboration came from geologist Dr. Yamirka Rojas-Agramonte, a member of the Isotope Geology group at JGU’s Institute of Geosciences. She has been studying the ages of the rocks from various islands in the archipelago since 2014 and was astounded when she suddenly came across the mineral zircon on a sandy beach. “It is extremely unusual to find zircons in basalt rock formations, such as those that predominate throughout the Galapagos,” explained Rojas-Agramonte. Zircon, a zirconium mineral, is commonly used to date ancient rocks. Zircon takes in trace amounts of uranium when it crystallizes in a newly-formed rock. Over time that uranium slowly decays to lead. The ratio between the lead formed and the uranium left can be used to determine the age of the zircon and thereby its host rock.
The zircon grains, commonly less than 0.2 millimeters in size, are first investigated under the microscope in Mainz and then, if appropriate, sent to China or Australia to be analyzed using a device called a sensitive high-resolution ion microprobe. “For the purposes of so-called SHRIMP dating, we have been collaborating for many years with a lab in Beijing, the Beijing SHRIMP Center,” said Professor Alfred Kröner of JGU, shortly before again departing with Galapagos zircon samples in his luggage.
Unexpected discovery of zircons in basalt rock
It has now been established that the zircon originates from young basalt rock, the main rock type that forms the Galapagos Islands. This rock is produced by volcanic eruptions such as those still occurring in the western sector of the archipelago. “Some of our newly discovered zircons are much older, however, than one would expect to find in young magmatic rock,” stated Kröner. How exactly these ancient zircons got into the Galapagos basalts remains a mystery. The explanation might well have wide-ranging implications for understanding the Earth’s crust-mantle system and the mantle geodynamics of the Earth. One of the current theories is that previously unexplained recycling processes might have taken place in the deep layers of the mantle.
Geoscientists at Johannes Gutenberg University Mainz and their colleagues from Spain, Australia, and Ecuador working in a wide range of different disciplines will, for the first time, be collaborating in this project in order to investigate the various hypotheses and search for further pieces of the puzzle that will help provide a solution. Over the next few years, they will be researching together on the Galapagos in a multi-disciplinary approach designed to explore a geological enigma, the significance of which could extend well beyond simply clarifying the formation of the Galapagos Islands.
Note: The above post is reprinted from materials provided by Universitaet Mainz.
This image shows a new piranha-like fish from Jurassic seas with sharp, pointed teeth that probably fed on the fins of other fishes. From the time of dinosaurs and from the same deposits that contained Archaeopteryx, scientists recovered both this flesh-tearing fish and its scarred prey. Credit: M. Ebert and T. Nohl
Researchers reporting in Current Biology on October 18 have described a remarkable new species of fish that lived in the sea about 150 million years ago in the time of the dinosaurs. The new species of bony fish had teeth like a piranha, which the researchers suggest they used as piranhas do: to bite off chunks of flesh from other fish.
As further support for that notion, the researchers also found the victims: other fish that had apparently been nibbled on in the same limestone deposits in South Germany (the quarry of Ettling in the Solnhofen region) where this piranha-like fish was found.
“We have other fish from the same locality with chunks missing from their fins,” says David Bellwood of James Cook University, Australia. “This is an amazing parallel with modern piranhas, which feed predominantly not on flesh but the fins of other fishes. It’s a remarkably smart move as fins regrow, a neat renewable resource. Feed on a fish and it is dead; nibble its fins and you have food for the future.”
The newly described fish is part of the world famous collections in the Jura-Museum in Eichstätt. It comes from the same limestone deposits that contained Archaeopteryx.
Careful study of the fossilized specimen’s well-preserved jaws revealed long, pointed teeth on the exterior of the vomer, a bone forming the roof of the mouth, and at the front of both upper and lower jaws. Additionally, there are triangular teeth with serrated cutting edges on the prearticular bones that lie along the side of the lower jaw.
The tooth pattern and shape, jaw morphology, and mechanics suggest a mouth equipped to slice flesh or fins, the international team of researchers report. The evidence points to the possibility that the early piranha-like fish may have exploited aggressive mimicry in a striking parallel to the feeding patterns of modern piranha.
“We were stunned that this fish had piranha-like teeth,” says Martina Kölbl-Ebert of Jura-Museum Eichstätt (JME-SNSB). “It comes from a group of fishes (the pycnodontids) that are famous for their crushing teeth. It is like finding a sheep with a snarl like a wolf. But what was even more remarkable is that it was from the Jurassic. Fish as we know them, bony fishes, just did not bite flesh of other fishes at that time. Sharks have been able to bite out chunks of flesh but throughout history bony fishes have either fed on invertebrates or largely swallowed their prey whole. Biting chunks of flesh or fins was something that came much later.”
Or, so it had seemed.
“The new finding represents the earliest record of a bony fish that bit bits off other fishes, and what’s more it was doing it in the sea,” Bellwood says, noting that today’s piranhas all live in freshwater. “So when dinosaurs were walking the earth and small dinosaurs were trying to fly with the pterosaurs, fish were swimming around their feet tearing the fins or flesh off each other.”
The researchers call the new find a “staggering example of evolutionary versatility and opportunism.” With one of the world’s best known and studied fossil deposits continuing to throw up such surprises, they intend to keep up the search for even more fascinating finds.
Reference:
Martina Kölbl-Ebert, Martin Ebert, David R. Bellwood, Christian Schulbert. A Piranha-like Pycnodontiform Fish from the Late Jurassic. Current Biology, 2018; DOI: 10.1016/j.cub.2018.09.013
Note: The above post is reprinted from materials provided by Cell Press.
Thylacoleo carnifex was smaller than an African lioness, but with 80 per cent as powerful a bite as a large African lion. Credit: Peter Schouten
Scientists believe Thylacoleo carnifex was probably a victim of the drying out of Australia, which began about 350,000 years ago, rather than from the impact of humans.
The extinction of one of Australia’s top predators, Thylacoleo carnifex – aka the marsupial lion – was likely a result of changing weather patterns and loss of habitat rather than human impacts, new research has found.
Palaeontologists from UNSW Sydney, University of Queensland and Vanderbilt University (Tennessee) addressed the question about the demise of the marsupial lion by looking into the powerful carnivore’s chemistry.
By studying the chemical signature preserved within fossil teeth, the team was able to determine that the marsupial lion hunted primarily in forests, rather than open habitats. This is supported by features of the skeleton that indicate it was an ambush hunter, relying on catching its prey unaware rather than running them down across an open landscape.
For nearly two million years the marsupial lion was one of Australia’s top predators. The animals were sized between leopards and African lionesses but had a bite that was about 80 per cent as strong as a large lion, enabling it to crush bones with its powerful jaws.
The study led by Professor Larisa DeSantis of Vanderbilt University posited that, despite being well-adapted for consuming flesh and bone, Thylacoleo was likely the victim of the drying out of Australia, which began about 350,000 years ago.
The marsupial lions persisted for thousands of years afterwards, as more and more forests disappeared. The animals survived even past the influx of humans to the continent roughly 60,000 years ago. Ultimately, the loss of forest habitats likely led to the extinction of these predators, with the last known record sometime between approximately 35 and 45 thousand years ago.
“These data provide evidence that the marsupial lion was an ambush predator and relied on prey that occupied denser cover,” Professor DeSantis said.
“As the landscape became drier and forests less-dense, these apex predators may have become less-effective hunters and succumbed to extinction.
“The study of these ancient fossils provides us with cautionary lessons for the future: climate change can impact even the fiercest predators.”
Specialised
The marsupial lion lived alongside the Thylacine, which survived until the 20th century. The preference of the Thylacine for prey from more open habitats likely led to its survival, despite having a much weaker bite than Thylacoleo carnifex.
Professor Michael Archer, a vertebrate palaeontologist at the University of New South Wales and one of the researchers involved said that because of its extraordinarily specialised dentition, Thylacoleo carnifex has been declared to be the most specialised mammalian carnivore that ever evolved anywhere in the world.
“Marsupial lions were far more specialised than African lions. They even had a proportionately larger brain than African lions as well as large, uniquely formidable, large can-opener-like thumb claws,” Professor Archer said.
“What’s increasingly clear now is that it evidently survived the arrival of humans 60,000 years ago, but apparently not the profound impacts of a rapidly drying climate that undermined the survival of a range of megafaunal mammals in Australia.”
According to Professor Archer, Thylacoleo carnifex was the last representative of this extraordinary group of flesh-eating marsupials. He said it was the largest of many kinds documented by Dr. Anna Gillespie of UNSW, on the basis of the 25 million-year-long fossil record from the Riversleigh World Heritage Area in Queensland. This record includes pussy-cat-sized marsupial carnivores like Microleo attenboroughi and leopard-sized species like Wakaleo schouteni.
Study co-author Gilbert Price of the University of Queensland said: “When you’re big and bitey, you can eat pretty much anything you want. But our findings show that even the top predators are no match for extreme climate change.”
An artist’s illustration shows a mosasaur feeding on a plesiosaur called elasmosaur, although there is no fossil evidence of mosasaurs feeding on this particular species. Illustration/Takashi Oda
Did prehistoric sea creatures called mosasaurs subdue prey by ramming them with their bony snouts like killer whales do today?
It’s a theory that University of Cincinnati biology professor Takuya Konishi proposed after taking a closer look at a newborn fossil specimen for his latest research study. Konishi will present his findings at October’s Society of Vertebrate Paleontology conference in Albuquerque, New Mexico.
“Killer whales don’t hunt big prey by biting. They hunt by ramming and tearing them apart after the prey is weak,” Konishi said. “They are chasing fast-moving animals so they use inertia. If they were swimming full speed at you, they would generate a lot of force. And their snout is conspicuously protruding.”
Mosasaur, the unlikely hero of the movie “Jurassic World,” was an enormous marine reptile that lived in the time of Tyrannosaurus rex during the Cretaceous Period more than 65 million years ago. They had a similar body shape as today’s orcas, with flippers, powerful tails and sharp teeth. Some grew bigger than orcas to nearly the size of a school bus.
Like orcas, they were the apex predators of the seas. The only thing mosasaurs had to fear were bigger mosasaurs.
In a study published this month in the Journal of Vertebrate Paleontology, Konishi re-examined fossils of a newborn mosasaur he first studied in Kansas while working on his master’s degree in 2004. About 20 small fragments of skull were unearthed in 1991 by paleontologist Michael Everhart in a rock formation called the Kansas Chalk renowned for marine fossils.
Initially, the specimen was identified as a mosasaur called Platecarpus, a species commonly found in that area during the same period 85 million years ago. The family Mosasauridae features more than 30 genera of species, so identifying a particular specimen from a handful of fossil fragments can be daunting.
“A colleague of mine told me mosasaurs are boring because they all look the same. That’s sort of true,” he said. “But once you know more about them you can begin to tell them apart.”
Some mosasaurs had short, powerful jaws capable of crushing the shells of sea turtles. Others had pointy teeth that suggested they feed mostly on fish.
Konishi was inspired to take a second look after a fellow researcher demonstrated how particular bones called quadrates were not as reliable in identifying species as researchers once thought. The telltale fossils of adults of different species look very similar in juveniles.
In the many years since Konishi first examined the baby mosasaur, he has become an expert on these seagoing lizards, including the largest of them called Tylosaurus. This was the creature that inspired “Jurassic World,” a meat-eating monster capable of hunting other mosasaurs and marine reptiles.
In re-examining the skull fragments from the newborn mosasaur, Konishi found it did not resemble other specimens of Platecarpus. While Platecarpus and other mosasaurs have teeth that begin virtually at the tip of their snouts, Tylosaurus has a bony protrusion called a rostrum that extends out from its face like an orca that might have served to protect its front teeth when they slammed into prey.
“It’s a subtle feature perhaps by horned dinosaur standards, but for us it really signifies what kind of mosasaur you’re looking at,” Konishi said. “If you have this protruding snout in this part of western Kansas, you’re a Tylosaurus.”
Like many other kinds of baby animals today, the baby mosasaur had not yet developed certain telltale features found in adults, Konishi said.
“The degree of snout development was nowhere near that of an adult, which made me look elsewhere such as the braincase to call it Tylosaurus in the end. It was the ugly duckling that hadn’t yet become the graceful swan,” Konishi said.
Unlike other mosasaur species, Konishi said the tylosaur had broader and more robust facial bones connected to a sturdy cranial vault that would have provided support as a battering ram.
Konishi pulled up a dramatic photo showing a breaching orca pummeling a large dolphin with its snout. The dolphin, a species called a false killer whale, was struck so hard that its body was contorted at a painful-looking angle.
“When orcas hunt dolphins and small whales, they subdue them by ramming them. And when you look at them, you see they have a protruding snout as well,” Konishi said.
The fossils represent the youngest and smallest specimen of Tylosaurus ever found. Everhart confirmed to Konishi that the baby mosasaur was found alone with no associated fossils. Mosasaurs didn’t lay eggs but gave birth to live young. That suggests the specimen was a free-swimming newborn rather than an embryo when it died, he said.
Just how the baby mosasaur perished is a matter of speculation. Only its skull was found. Konishi said the mosasaur could have succumbed to countless mishaps from predation to accident to disease.
It took a miracle of improbability that the baby mosasaur was found in the first place, he said.
Finding any baby dinosaur, or marine reptile in this case, is extremely rare for the simple reason that baby animals often end up as someone else’s dinner. The bones of baby animals are lighter and more likely to scatter. But in this case, bones that weren’t chewed up reached the ocean floor where they were covered in sediment and remained for millions of years until the seas receded and the former ocean floor became the wheat fields and farmlands of today’s Kansas.
“And luckily an expert on mosasaurs was searching in exactly that spot and had sharp enough eyes to find it — all separated by about 85 million years,” Konishi said.
“Most fossils are fragmentary. You almost never find an entirely articulated fossil in the ground. That’s near fantasy,” Konishi said. “Luckily, the remaining bones were buried and became fossilized.”
Konishi’s theory strikes a chord with orca experts such as Ken Balcomb, senior scientist with the nonprofit Center for Whale Research outside Seattle, Washington. Balcomb has been studying orcas for 43 years. He has seen firsthand the myriad clever methods they employ to hunt different prey.
“They pummel their prey quite a bit. They will throw their body against a gray whale. They’ll ram great white sharks, too,” Balcomb said.
But Balcomb said they’re choosy about what and how they attack, often using their flukes or whole body rather than their heads. They even distinguish between different types of prey.
“They know which kinds of seals will fight back,” Balcomb said. “So they’re cautious. They don’t want to get hurt.”
Contributing to Konishi’s study were Paulina Jiménez-Huidobro and Michael Caldwell, both of the University of Alberta. The study was funded in part by the Natural Sciences and Engineering Research Council of Canada.
Konishi said this better understanding of the development of baby mosasaurs could help scientists learn more about fossils of other baby dinosaurs and marine reptiles that look markedly different from their parents.
“We now have a bit better insight into how this trademark feature evolved in this lineage,” he said. “It’s a good starting point for more studies in the future.”
Reference:
Takuya Konishi, Paulina Jiménez-Huidobro, Michael W. Caldwell. The Smallest-Known Neonate Individual of Tylosaurus (Mosasauridae, Tylosaurinae) Sheds New Light on the Tylosaurine Rostrum and Heterochrony. Journal of Vertebrate Paleontology, 2018; 1 DOI: 10.1080/02724634.2018.1510835
An underwater picture of the modern demosponge species Rhabdastrella globostellata, which make the same 26-mes steroids that the researchers found in ancient rocks. Credit: Paco Cárdenas
Researchers at the University of California, Riverside, have found the oldest clue yet of animal life, dating back at least 100 million years before the famous Cambrian explosion of animal fossils.
The study, led by Gordon Love, a professor in UCR’s Department of Earth Sciences, was published today in Nature Ecology & Evolution. The first author is Alex Zumberge, a doctoral student working in Love’s research group.
Rather than searching for conventional body fossils, the researchers have been tracking molecular signs of animal life, called biomarkers, as far back as 660-635 million years ago during the Neoproterozoic Era. In ancient rocks and oils from Oman, Siberia, and India, they found a steroid compound produced only by sponges, which are among the earliest forms of animal life.
“Molecular fossils are important for tracking early animals since the first sponges were probably very small, did not contain a skeleton, and did not leave a well-preserved or easily recognizable body fossil record,” Zumberge said. “We have been looking for distinctive and stable biomarkers that indicate the existence of sponges and other early animals, rather than single-celled organisms that dominated the earth for billions of years before the dawn of complex, multicellular life.”
The biomarker they identified, a steroid compound named 26-methylstigmastane (26-mes), has a unique structure that is currently only known to be synthesized by certain species of modern sponges called demosponges.
“This steroid biomarker is the first evidence that demosponges, and hence multicellular animals, were thriving in ancient seas at least as far back as 635 million years ago,” Zumberge said.
The work builds from a 2009 study by Love’s team, which reported the first compelling biomarker evidence for Neoproterozoic animals from a different steroid biomarker, called 24-isopropylcholestane (24-ipc), from rocks in South Oman. However, the 24-ipc biomarker evidence proved controversial since 24-ipc steroids are not exclusively made by demosponges and can be found in a few modern algae. The finding of the additional and novel 26-mes ancient biomarker, which is unique to demosponges, adds extra confidence that both compounds are fossil biomolecules produced by demosponges on an ancient seafloor.
The study also provides important new constraints on the groups of modern demosponges capable of producing unique steroid structures, which leave a distinctive biomarker record. The researchers found that within modern demosponges, certain taxonomic groups preferentially produce 26-mes steroids while others produce 24-ipc steroids.
“The combined Neoproterozoic demosponge sterane record, showing 24-ipc and 26-mes steranes co-occurring in ancient rocks, is unlikely attributed to an isolated branch or extinct stem-group of demosponges,” Love said. “Rather, the ability to make such unconventional steroids likely arose deep within the demosponge phylogenetic tree but now encompasses a wide coverage of modern demosponge groups.”
Reference:
J. Alex Zumberge, Gordon D. Love, Paco Cárdenas, Erik A. Sperling, Sunithi Gunasekera, Megan Rohrssen, Emmanuelle Grosjean, John P. Grotzinger, Roger E. Summons. Demosponge steroid biomarker 26-methylstigmastane provides evidence for Neoproterozoic animals. Nature Ecology & Evolution, 2018; DOI: 10.1038/s41559-018-0676-2
This photo shows from left to right a partial snout with teeth and tooth bases, partial braincase, and a section of upper jaw with tooth bases. Credit: Ms. Christina Byrd, Paleontology Collections Manager at the Sternberg Museum of Natural History in Hays, Kansas
The smallest Tylosaurus mosasaur fossil ever found has been revealed in a new study in the Journal of Vertebrate Paleontology and surprisingly it lacks a trademark feature of the species.
The fossil, likely to be that of a newborn, does not have the recognizable long snout typically seen in the species. The lack of this snout initially perplexed researchers, who struggled to identify which group of mosasaurs it belonged to.
After examining and comparing the fossil to young specimens of closely-related species, such as T. nepaeolicus and T. proriger which already had identifiable noses, researchers finally deemed it to be a young Tylosaurus.
Lead author Professor Takuya Konishi, of the Department of Biological Sciences at the University of Cincinnati said, “Having looked at the specimen in 2004 for the first time myself, it too took me nearly 10 years to think out of that box and realize what it really was — a baby Tylosaurus yet to develop such a snout.
For those 10 years or so, I had believed too that this was a neonate of Platecarpus, a medium-sized (5-6m) and short-snouted mosasaur, not Tylosaurus, a giant (up to 13m) mosasaur with a significantly protruding snout.”
The lack of snout in the baby specimen found suggests to researchers that the development of this feature happens extremely quickly, between birth and juvenile stage — something that previous studies on the species had failed to notice.
Konishi further commented, “Yet again, we were challenged to fill our knowledge gap by testing our preconceived notion, which in this case was that Tylosaurus must have a pointy snout, a so-called ‘common knowledge.’
As individual development and evolutionary history are generally linked, the new revelation hints at the possibility that Tylosaurus adults from much older rock units may have been similarly short-snouted, something we can test with future discoveries.”
The fragments found include a partial snout with teeth and tooth bases, partial braincase, and a section of upper jaw with tooth bases. From this, they can estimate the entire baby skull to have been around 30cm (1ft) in total.
Tylosaurus belong to one of the largest-known groups of mosasaurs, up to 13m long, the front 1.8 m of that body being its head. The baby, therefore, was about 1/6 the size of such an adult.
Michael J. Everhart, a Kansas native and a special curator of paleontology at the Sternberg Museum of Natural History, Hays, Kansas, found the tiny specimens in 1991 in the lower Santonian portion of the Niobrara Chalk, in Kansas, which are now housed at the museum. The paper was co-authored by Paulina Jiménez-Huidobro and Michael W. Caldwell of the University of Alberta, Canada.
Reference:
Takuya Konishi, Paulina Jiménez-Huidobro, Michael W. Caldwell. The Smallest-Known Neonate Individual of Tylosaurus (Mosasauridae, Tylosaurinae) Sheds New Light on the Tylosaurine Rostrum and Heterochrony. Journal of Vertebrate Paleontology, 2018; 1 DOI: 10.1080/02724634.2018.1510835
An illustration of how the smaller mammals will have to evolve and diversify over the next 3-5 million years to make up for the loss of the large mammals. Credit: Matt Davis, Aarhus University
We humans are exterminating animal and plant species so quickly that nature’s built-in defence mechanism, evolution, cannot keep up. An Aarhus-led research team calculated that if current conservation efforts are not improved, so many mammal species will become extinct during the next five decades that nature will need 3-5 million years to recover.
There have been five upheavals over the past 450 million years when the environment on our planet has changed so dramatically that the majority of Earth’s plant and animal species became extinct. After each mass extinction, evolution has slowly filled in the gaps with new species.
The sixth mass extinction is happening now, but this time the extinctions are not being caused by natural disasters; they are the work of humans. A team of researchers from Aarhus University and the University of Gothenburg has calculated that the extinctions are moving too rapidly for evolution to keep up.
If mammals diversify at their normal rates, it will still take them 5-7 million years to restore biodiversity to its level before modern humans evolved, and 3-5 million years just to reach current biodiversity levels, according to the analysis, which was published recently in the scientific journal, PNAS.
Some species are more distinct than others
The researchers used their extensive database of mammals, which includes not only species that still exist, but also the hundreds of species that lived in the recent past and became extinct as Homo sapiens spread across the globe. This meant that the researchers could study the full impact of our species on other mammals.
However, not all species have the same significance. Some extinct animals, such as the Australian leopard-like marsupial lion Thylacoleo, or the strange South American Macrauchenia (imagine a lama with an elephant trunk) were evolutionary distinct lineages and had only few close relatives. When these animals became extinct, they took whole branches of the evolutionary tree of life with them. We not only lost these species, we also lost the unique ecological functions and the millions of years of evolutionary history they represented.
“Large mammals, or megafauna, such as giant sloths and sabre-toothed tigers, which became extinct about 10,000 years ago, were highly evolutionarily distinct. Since they had few close relatives, their extinctions meant that entire branches of Earth’s evolutionary tree were chopped off” says palaeontologist Matt Davis from Aarhus University, who led the study. And he adds:
“There are hundreds of species of shrew, so they can weather a few extinctions. There were only four species of sabre-toothed tiger; they all went extinct.”
Long waits for replacement rhinos
Regenerating 2.5 billion years of evolutionary history is hard enough, but today’s mammals are also facing increasing rates of extinction. Critically endangered species such as the black rhino are at high risk of becoming extinct within the next 50 years. Asian elephants, one of only two surviving species of a once mighty mammalian order that included mammoths and mastodons, have less than a 33 percent chance of surviving past this century.
The researchers incorporated these expected extinctions in their calculations of lost evolutionary history and asked themselves: Can existing mammals naturally regenerate this lost biodiversity?
Using powerful computers, advanced evolutionary simulations and comprehensive data about evolutionary relationships and body sizes of existing and extinct mammals, the researchers were able to quantify how much evolutionary time would be lost from past and potential future extinctions as well as how long recovery would take.
The researchers came up with a best-case scenario of the future, where humans have stopped destroying habitats and eradicating species, reducing extinction rates to the low background levels seen in fossils. However, even with this overly optimistic scenario, it will take mammals 3-5 million years just to diversify enough to regenerate the branches of the evolutionary tree that they are expected to lose over the next 50 years. It will take more than 5 million years to regenerate what was lost from giant Ice Age species.
Prioritizing conservation work
“Although we once lived in a world of giants: giant beavers, giant armadillos, giant deer, etc., we now live in a world that is becoming increasingly impoverished of large wild mammalian species. The few remaining giants, such as rhinos and elephants, are in danger of being wiped out very rapidly,” says Professor Jens-Christian Svenning from Aarhus University, who heads a large research program on megafauna, which includes the study.
The research team doesn’t have only bad news, however. Their data and methods could be used to quickly identify endangered, evolutionarily distinct species, so that we can prioritise conservation efforts, and focus on avoiding the most serious extinctions.
As Matt Davis says: “It is much easier to save biodiversity now than to re-evolve it later.”
Reference:
Matt Davis, Søren Faurby, Jens-Christian Svenning. Mammal diversity will take millions of years to recover from the current biodiversity crisis. Proceedings of the National Academy of Sciences, 2018; 201804906 DOI: 10.1073/pnas.1804906115
Note: The above post is reprinted from materials provided by Aarhus University.
Artist’s interpretation of Sarahsaurus aurifontanalis. The dinosaur was about the size of a car and had powerful forelimbs with large claws. It lived during the Early Jurassic in North America. Credit: Brian Engh
By the time non-avian dinosaurs went extinct, plant-eating sauropods like the Brontosaurus had grown to gargantuan proportions. Weighing in as much as 100 tons, the long-neck behemoths are the largest land animals to ever walk the earth.
How they grew so large from ancestors that were small enough to be found in a modern-day petting zoo has remained a mystery. A new, in-depth anatomical description of the best preserved specimens of a car-sized sauropod relative from North America could help paleontologists with unraveling the mystery.
Adam Marsh, a paleontologist at Petrified Forest National Park, led the description of the dinosaur while earning his master’s degree from The University of Texas at Austin Jackson School of Geosciences. The findings were published on Oct. 10 in the journal PLOS ONE. Marsh co-authored the paper with his advisor, Jackson School Professor Timothy Rowe.
The dinosaur — called Sarahsaurus aurifontanalis — lived about 185 million years ago during the Early Jurassic. It could hold important clues about sauropods’ size because it belonged to the dinosaur grouping that preceded them. Its evolutionary placement combined with the exquisite preservation of the specimens is giving researchers a detailed look into its anatomy and how it relates to its larger cousins.
“Sarahsaurus preserves in its anatomy the anatomical changes that were happening in the Late Triassic and Early Jurassic that were occurring in the evolutionary lineage,” Marsh said. “It can help tell us how getting big happens.”
The description is based on two skeletons discovered in Arizona by Rowe in 1997. The bones belong to the Navajo Nation, which owns the land where the fossils were discovered, and are curated by the Jackson School Museum of Earth History Vertebrate Paleontology Collections. The bones are slightly crushed, and in some cases still linked together into body parts such as the hand and tail. The only major missing part is the skull.
“The specimens are well preserved in three dimensions and remarkably complete, which is very rare in the fossil record,” said collections Director Matthew Brown. “Such complete specimens help paleontologists better understand the fragmentary and incomplete fossils remains we typically find.”
Marsh describes Sarahsaurus as a “ground sloth-like” dinosaur. It stood upright, walked on its hind-legs and had powerful forelimbs with a large, curved claw capping the first finger of each hand. It had a lot in common with the earliest sauropod ancestors — like walking on two legs — but it was also starting to show features that would foreshadow how its massive relatives would evolve — such as an increase in body size and a lengthening of the neck vertebrae.
“It’s starting to gain the characters of getting large compared to the earliest members of the group,” Marsh said.
Size and neck-length are features that sauropods would take to extremes as they evolved. By studying these traits and others in Sarahsaurus, and seeing how they compare to those of other dinosaurs, scientists can help reveal how these changes occurred across evolutionary history and how different dinosaurs relate to one another.
For example, the anatomical review helped clarify the relationship between Sarahsaurus and two other sauropod relatives that lived in North America during the Early Jurassic. The researchers found that the three don’t have a common North American ancestor — instead they evolved from dinosaur lineages that came to North America independently.
Marsh is currently working on another study that could shed more light on how sauropods evolved. Led by Sterling Nesbitt, an assistant professor at Virginia Tech and research associate at the Jackson School’s vertebrate collections, the project involves tracking anatomical differences in dinosaur limb bones to determine which features relate to evolution and which relate to the age of an animal. Marsh said that the two Sarahsaurus skeletons examined for this paper are a great addition to the project.
“We’ve got two individuals from basically the same hole in the ground with different bumps and grooves on their femora,” Marsh said. “It lends itself really well to this comprehensive anatomical description and it’s going to be really important for comparisons of early dinosaur anatomy.”
The research was funded by the Jackson School of Geosciences and the National Science Foundation. The Sarahsaurus specimens were collected under permit from the Navajo Nation Minerals Department.
Reference:
Adam D. Marsh, Timothy B. Rowe. Anatomy and systematics of the sauropodomorph Sarahsaurus aurifontanalis from the Early Jurassic Kayenta Formation. PLOS ONE, 2018; 13 (10): e0204007 DOI: 10.1371/journal.pone.0204007
An international team of earth scientists has linked the establishment of the Mekong River to a period of major intensification of the Asian monsoon during the middle Miocene, about 17 million years ago, findings that supplant the assumption that the river incised in response to tectonic causes. Their findings are the subject of a paper published in Nature Geoscience on Oct. 15.
Gregory Hoke, associate professor and associate chair of Earth sciences, and recent SU doctoral student Gregory Ruetenik, now a post-doctoral researcher at the University of Wisconsin, co-authored the article with colleagues from China, France, Sweden, Australia, and the United States. Hoke’s initial collaboration with first author Jungsheng Nie was co-editing a special volume on the growth of the Tibetan Plateau during the Cenozoic.
The Mekong River is the longest in Southeast Asia and the tenth largest worldwide in terms of water volume. Originating in the Tibetan Plateau, the Mekong runs through China, Myanmar, Laos, Thailand, Cambodia and Vietnam. The Chinese portion of the river (Lancang Jiang) occupies a spectacular canyon that is between 1-2 kilometers deep relative to the surrounding landscape.
“When the upper half of that river was established and at what point it incised the canyon it occupies today, as well as whether it was influenced by climate or by tectonics, has been debated by geologists for the last quarter century,” says Hoke. “Our work establishes when major canyon incision began and identifies the most likely mechanism responsible for that incision: an intensification of the Asian monsoon during the warmest period over the last 23 million years, the Middle Miocene climate optimum.”
River incision is the natural process by which a river cuts downward into its bed, deepening the active channel. “In most cases, you can attribute incision to some sort of some change in the overall relief of a landscape, which is typically interpreted to be in response to a tectonic influence,” says Hoke.
The standard interpretation for river incision of the Mekong and adjacent Yangtze basins had been a response to topographic growth of the Tibetan Plateau. However, a recent string of studies have determined that the southeastern margin of Tibet was already at or near modern elevations by 40 million years ago, throwing a monkey wrench into that hypothesis.
Using thermochronology of apatite minerals extracted from bedrock samples collected along the walls of the river canyon, the scientists were able to numerically model the cooling history of the rock as the river incised, which revealed synchronous downcutting at 15-17 million years along the entire river. Synchronous downcutting points towards a non-tectonic cause for incision. Ruetenik modeled whether or not a stronger monsoon was capable of achieving the magnitude of downcutting over the relatively short duration of the middle Miocene climate optimum using landscape models he developed during his SU doctoral study. According to Hoke, “This solves how river incision occurred in the absence of any clear pulse of plateau growth along the southeast margin of Tibet. In essence, an enhanced monsoon did a tremendous amount of work sawing through the landscape during the middle Miocene climate optimum.”
Previously, Hoke studied buried river sands in cave deposits to reconstruct the incision history of the Yangtze river, the next river to the east of the Mekong. “We found a sequence of ages that look similar to those from the thermochrometers in the Mekong,” he says of his findings, published in Geophysical Research Letters in 2016. He next hopes subsequent studies will be able to extend the results from this new Nature Geoscience paper to the three other big rivers that drain the southeastern margin of the Tibetan Plateau.
Reference:
Junsheng Nie, Gregory Ruetenik, Kerry Gallagher, Gregory Hoke, Carmala N. Garzione, Weitao Wang, Daniel Stockli, Xiaofei Hu, Zhao Wang, Ying Wang, Thomas Stevens, Martin Danišík, Shanpin Liu. Rapid incision of the Mekong River in the middle Miocene linked to monsoonal precipitation. Nature Geoscience, 2018; DOI: 10.1038/s41561-018-0244-z
Note: The above post is reprinted from materials provided by Syracuse University. Original written by Renee Levy.
Meltwater accumulation within 160 feet of the surface causes these bright, white reflections to dim to grey from June to early August before stabilizing in late August. Credit: Alexander Kendrick
Stanford scientists have revealed the presence of water stored within a glacier in Greenland, where the rapidly changing ice sheet is a major contributor to the sea-level rise North America will experience in the next 100 years. This observation — which came out of a new way of looking at existing data — has been a missing component for models aiming to predict how melting glaciers will impact the planet.
The group made the discovery looking at data intended to reveal the changing shape of Store Glacier in West Greenland. But graduate student Alexander Kendrick figured out that the same data could measure something much more difficult to observe: its capacity to store water. The resulting study, published in Geophysical Research Letters, presents evidence of glacier meltwater from the surface being stored within damaged, solid ice. While ice melting at the surface has been well documented, little is known about what happens below glacier surfaces, and this observation of liquid water stored within solid ice may explain the complex flow behavior of some Greenland glaciers.
“Things like this don’t always come along, but when they do, that is the real ‘joy of the discovery’ component of Earth science,” said co-author Dustin Schroeder, an assistant professor of geophysics at Stanford University’s School of Earth, Energy & Environmental Sciences (Stanford Earth). “This paper not only highlights this component’s existence, but gives you a way to observe it in time.”
Surface meltwater plays an important role in Greenland by lubricating the bottoms of ice sheets and impacting how retreating glaciers are affected by the ocean. The process of how the glaciers melt and where the water flows contributes to their behavior in a changing climate, as these factors could alter glaciers’ response to melting or impact the timeline for sea-level rise. Knowing that some liquid is intercepted within glaciers after melting on the surface may help scientists more accurately predict oceanic changes and help people prepare for the future, Schroeder said.
“All of our predictions of sea-level rise are missing this meltwater component,” Schroeder said. “I think we’re only just realizing how important it is to understand at a fundamental physical scale what glacier meltwater does on its way from the surface to the bed.”
A different perspective
The researchers analyzed data from a high-resolution, low-power radio-echo sounder (ApRES) collected hourly from May to November 2014. Behaving like an ultrasound for ice, the radar sends an electronic wave that bounces off variations in ice density to create an image of ice structure that shows how quickly the ice melts or moves over time.
When the team plotted the radar data, it looked suspicious, said Kendrick, who was lead author on the paper. They tested ideas such as temperature variations and battery fluctuations to account for what they saw, then wondered if water within the ice was causing the peculiarity. By looking at a different aspect of the data, Kendrick noticed that the idiosyncrasies coming from deep within the glacier correlated with information from a nearby weather station indicating that the glacier had been melting at the time the data was collected. That finding backed up the idea that they were detecting water that had melted on the surface and then trickled down into the glacier, where it got trapped.
“This is a new way you could use these instruments to answer scientific questions — instead of just looking at changes in the ice thickness, we’re also looking at changes in the ice properties itself,” said co-author Winnie Chu, a postdoctoral researcher in Schroeder’s lab. “Alex set up the groundwork for trying to understand how this meltwater storage changes through time.”
The study reveals a significant amount of meltwater produced from the local area surrounding the radar is being intercepted and stored within the ice in a region extending between 15 to 148 feet below the surface during the summer, then released or refrozen during winter.
“The water system of Greenland is critical for understanding what’s happening on the planet,” said Schroeder, who is also a fellow at the Stanford Woods Institute for the Environment. “This component Alex has discovered shows that there is a piece of this glacier in particular — and maybe the entire Greenland hydrologic system in general — that we just were not modeling or thinking about in this way.”
The researchers hope this new geophysical method can be used to understand how meltwater impacts other glaciers and glacial systems, as well.
Reference:
A. K. Kendrick, D. M. Schroeder, W. Chu, T. J. Young, P. Christoffersen, J. Todd, S. H. Doyle, J. E. Box, A. Hubbard, B. Hubbard, P. V. Brennan, K. W. Nicholls, L. B. Lok. Surface Meltwater Impounded by Seasonal Englacial Storage in West Greenland. Geophysical Research Letters, 2018; DOI: 10.1029/2018GL079787
The University of California, San Diego’s outdoor shake table in Scripps Ranch will soon give engineers a truer sense of the fury released when big earthquakes erupt in places around the world,
The National Science Foundation gave the school $16.3 million to upgrade the center so it can more accurately simulate quakes, a complex phenomenon that in some years kills hundreds of thousands of people worldwide.
The table is the largest of its kind and has conducted experiments that have led to tougher building and design codes for bridges and housing. But it can move structures only backward and forward. Quakes can move the ground in many directions.
Engineers will modify the table so that it also can move up and down, right and left, and simulate the pitch, roll and yaw that can come with ground motion. Collectively, these movements are called the “six degrees of freedom.”
The upgrade involves adding pistons and power to a table that’s used by researchers from around nation to simulate quakes big enough to send seismic waves coursing through the earth for weeks.
“We will be able to reproduce earthquake motions with the most accuracy of any shake table in the world,” said Joel Conte, the structural engineer who is overseeing the project. “This will accelerate the discovery of the knowledge engineers need to build new bridges, power plants, dams, levees, telecommunication towers, wind turbines, retaining walls, tunnels, and to retrofit older structures. It will enhance the resiliency of our communities.”
The upgrade comes at a worrisome time in California.
In June, the U.S. Geological Survey said 38 high-rise buildings in San Francisco constructed between 1964 and 1994 could buckle if they were hit by the type of earthquake that devastated the city in 1906. The list includes the Transamerica Pyramid in the Financial District.
There’s also concern about a newer skyscraper, the 58-story Millennium Tower, which has been sinking and tilting, making it more vulnerable to big quakes.
San Diego is also on shaky ground.
In 2017, the Earthquake Engineering Research Institute released a report that says that 2,000 people could die in San Diego if a 6.9 magnitude quake erupts on the Rose Canyon fault, which runs through the heart of the city. Potential property damage: $40 billion.
The EERI emphasized that the figures are just estimates because modeling the complexities of earthquakes is hard to do with existing models and technology.
Even so, engineers have made progress.
Since it opened in the late 1980s, UC San Diego’s Powell Laboratories has been heavily involved in developing and testing key portions of roads and bridges, leading to changes in building codes.
The shake table was added in 2004 to give scientists and engineers better ability to test large structures, from wood-frame buildings to bridge columns to a 70-foot wind turbine.
The need for such a table had been apparent for decades.
The 6.7 magnitude Northridge quake in 1994 appears to have caused the ground to move vertically and horizontally. That vertical movement may be the reason that some bridge support columns rose and pierced the decks of bridges.
Such wild ground motion wasn’t unknown to engineers. The 1971 San Fernando earthquake, which measured 6.6, appears to have caused the soil to rotate in some areas. That, in turn, may have caused some buildings to turn like corkscrews.
The movement contributed to the billions of dollars in property damage inflicted by the quake.
The table has been used to simulate some of those jarring events, notably the Northridge quake.
That earthquake caused the collapse of a parking garage at Cal State Northridge. Engineers from the University of Arizona built a similar garage in 2008, and then shook it harder than the real quake.
The experiment revealed a great deal about how such structures absorb and distribute energy, leading to a strengthening of national building codes.
More recently, a team led by UC San Diego built and tested a five-story building that had many of the features of a hospital—such as an ICU and a surgery suite—and a working elevator and a sprinkler system. The goal was to understand what would happen inside a hospital during a catastrophic quake.
To ensure that they didn’t miss anything, engineers placed 500 sensors in and around the building, and installed 70 cameras.
Then they simulated several high-intensity earthquakes, and later set part of the building on fire to replicate a frequent aftereffect of quakes.
“What we are doing is the equivalent of giving a building an EKG,” lead engineer Tara Hutchinson said.
The experiment helped lead to the design of safer hospitals, and it was followed by a project that focused on a subject of great concern in California—four-story wood-frame residential buildings that have garages on the first floor.
The structures -built mostly in the 1920s, ’30s and ’40s—are now considered vulnerable to collapse in a huge quake.
In 2013, Colorado State University built one of the structures on the shake table and outfitted it with various types of retrofitting to see what would happen.
The result was good, and bad.
The building survived shake tests with the retrofitting in place. When it was taken out, calamity ensued.
“There was creaking and crunching, then a thunderous collapse, followed by dust and debris floating up,” said John W. van de Lindt, the Colorado State engineer who led the project.
Now, Lindt is drawing up plans for a 10-story building that will be built on the same spot. But this time, he’ll be able to move the building in any direction he wants.
“The U.S. and California have really been at the forefront of this kind of research,” Lindt said. “The upgrade will help us keep pace with the world. We really need this.”
One of the petrified remains of a victim of the eruption of Vesuvius volcano in 79 BC
A newly-discovered inscription at Pompeii proves the city was destroyed by Mount Vesuvius after October 17, 79 AD and not on August 24 as previously thought, archeologists said Tuesday.
Archeologists recently discovered that a worker had inscribed the date of “the 16th day before the calends of November”, meaning October 17, on a house at Pompeii, the head of archeology at the site, Massimo Osanna, told Italian media.
Pompeii and Herculaneum were previously thought to have been destroyed by the massive eruption of Mount Vesuvius on August 24, based on contemporary writings and archeological finds.
Nevertheless, evidence such as autumnal fruits on branches found in the ashen ruins had suggested a later date since the 19th century, Osanna said.
“Today, with much humility, perhaps we will rewrite the history books because we date the eruption to the second half of October,” said Italy’s Minister of Culture Alberto Bonisoli.
Pompeii is the second most visited tourist site in Italy, after the Colosseum in Rome, with more than three million visitors in the first eight months of this year.
Note: The above post is reprinted from materials provided by AFP.
Jaw with a durophagous dentition consisting of teeth with thick enamel of the gilthead sea bream (Sparus aurata): The large molariform tooth was used for oxygen isotope analysis and to estimate the size of the fish. Credit: Copyright Guy Sisma-Ventura
Some 3,500 years ago, there was already a brisk trade in fish on the shores of the southeastern Mediterranean Sea. This conclusion follows from the analysis of 100 fish teeth that were found at various archeological sites. The saltwater fish from which these teeth originated is the gilthead sea bream, which is also known as the dorade. It was caught in the Bardawil lagoon on the northern Sinai coast and then transported from Egypt to sites in the southern Levant. This fish transport persisted for about 2,000 years, beginning in the Late Bronze Age and continuing into the early Byzantine Period, roughly 300 to 600 AD. “Our examination of the teeth revealed that the sea bream must have come from a very saline waterbody, containing much more salt than the water in the Mediterranean Sea,” said Professor Thomas Tütken of Johannes Gutenberg University Mainz (JGU). The geoscientist participated in the study together with colleagues from Israel and Göttingen. The Bardawil lagoon formed 4,000 years ago, when the sea level finally stabilized after the end of the last Ice Age. The lagoon was fished intensively and was the point of origin of an extensive fish trade.
As demonstrated by archeological finds, fishing was an important economic factor for many ancient cultures. In the southern Levant, the gilthead sea bream with the scientific name of Sparus aurata was already being fished by local costal fishermen 50,000 years ago. More exotic fish, such as the Nile perch, were already being traded between Egypt and Canaan over 5,000 years ago. However, the current study shows the extent to which the trade between the neighbors increased in the Late Bronze Age and continued for 2,000 years into the Byzantine Period. “The Bardawil lagoon was apparently a major source of fish and the starting point for the fish deliveries to Canaan, today’s Israel, even though the sea bream could have been caught there locally,” stated co-author Professor Andreas Pack from the University of Göttingen.
Fish teeth document over 2,000 years of trade
Gilthead sea bream are a food fish that primarily feed on crabs and mussels. They have a durophagous dentition with button-shaped teeth that enable them to crush the shells to get at the flesh. For the purposes of the study, 100 large shell-cracking teeth of gilthead sea bream were examined. The teeth originate from 12 archeological sites in the southern Levant, some of which lie inland, some on the coast, and cover a time period from the Neolithic to the Byzantine Period. One approach of the researchers was to analyze the content of the oxygen isotopes ^18O and ^16O in the tooth enamel of the sea bream. The ratio of ^18O to ^16O provides information on the evaporation rate and thus on the salt content of the surrounding water in which the fish lived. In addition, the researchers were able to estimate the body size of the fish on the basis of the size of the shell-cracking teeth.
The analyses showed that some of the gilthead sea bream originated from the southeastern Mediterranean but that roughly three out of every four must have lived in a very saline body of water. The only water that comes into question in the locality is that of the Bardawil lagoon, the hypersaline water of which has a salt content of 3.9 to 7.4 percent, providing the perfect environment for the growth of sea bream. The Bardawil lagoon on the Sinai coast is approximately 30 kilometers long, 14 kilometers wide, and has a maximum depth of 3 meters. It is separated from the Mediterranean by a narrow sand bar.
“There was a mainland route from there to Canaan, but the fish were probably first dried and then transported by sea,” added Tütken. Even back then, sea bream were probably a very popular food fish, although it is impossible to estimate actual quantities consumed. However, it became apparent that the fish traded from the period of the Late Bronze Age were significantly smaller than in the previous era.
According to the researchers, this reduction in body size is a sign of an increase in the intensity of fishing that led to a depletion of stocks, which is to be witnessed also in modern times. “It would seem that fishing and the trade of fish expanded significantly, in fact to such a degree that the fish did not have the chance to grow as large,” continued Tütken, pointing out that this was an early form of the systematic commercial exploitation of fish, a type of proto-aquaculture, which persisted for some 2,000 years.
Reference:
Sisma-Ventura Guy, Tütken Thomas, Zohar Irit, Pack Andreas, Sivan Dorit, Lernau Omri, Gilboa Ayelet, Bar-Oz Guy. Tooth oxygen isotopes reveal Late Bronze Age origin of Mediterranean fish aquaculture and trade. Scientific Reports, 2018; 8 (1) DOI: 10.1038/s41598-018-32468-1
An artistic reconstruction of the extinct flying squirrel Miopetaurista neogrivensis. Credit: Oscar Sanisidro (CC BY-NC-SA 4.0)
The oldest flying squirrel fossil ever found has unearthed new insight on the origin and evolution of these airborne animals.
Writing in the open-access journal eLife, researchers from the Institut Català de Paleontologia Miquel Crusafont (ICP) in Barcelona, Spain, described the 11.6-million-year-old fossil, which was discovered in Can Mata landfill, approximately 40 kilometers outside the city.
“Due to the large size of the tail and thigh bones, we initially thought the remains belonged to a primate,” says first author Isaac Casanovas-Vilar, researcher at the ICP. In fact, and much to the disappointment of paleoprimatologists, further excavation revealed that it was a large rodent skeleton with minuscule specialised wrist bones, identifying it as Miopetaurista neogrivensis — an extinct flying squirrel.
Combining molecular and paleontological data to carry out evolutionary analyses of the fossil, Casanovas-Vilar and the team demonstrated that flying squirrels evolved from tree squirrels as far back as 31 to 25 million years ago, and possibly even earlier.
In addition, their results showed that Miopetaurista is closely related to an existing group of giant flying squirrels called Petaurista. Their skeletons are in fact so similar that the large species that currently inhabits the tropical and subtropical forests of Asia could be considered living fossils.
With 52 species scattered across the northern hemisphere, flying squirrels are the most successful group of mammals that adopted the ability to glide. To drift between trees in distances of up to 150 metres, these small animals pack their own ‘parachute’: a membrane draping between their lower limbs and the long cartilage rods that extend from their wrists. Their tiny, specialised wrist bones, which are unique to flying squirrels, help support the cartilaginous extensions.
But the origin of these animals is highly debated. While most genetic studies point towards the group splitting from tree squirrels about 23 million years ago, some 36-million-year-old remains that could belong to flying squirrels have previously been found. “The problem is that these ancient remains are mainly teeth,” Casanovas-Vilar explains. “As the dental features used to distinguish between gliding and non-gliding squirrels may actually be shared by the two groups, it is difficult to attribute the ancient teeth undoubtedly to a flying squirrel. In our study, we estimate that the split took place around 31 and 25 million years ago, earlier than previously thought, suggesting the oldest fossils may not belong to flying squirrels.
“Molecular and paleontological data are often at odds, but this fossil shows that they can be reconciled and combined to retrace history,” he adds. “Discovering even older fossils could help to retrace how flying squirrels diverged from the rest of their evolutionary tree.”
An exceptional site in a rubbish dump
The Can Mata landfill holds a set of more than 200 sites ranging in age between 12.6 and 11.4 Ma (middle to late Miocene). In the last 20 years, excavations carried out by the ICP in Can Mata have led to the identification of more than 80 species of mammals, birds, amphibians and reptiles. A remarkable number of primate remains from the site have revealed three new species of hominoids, nicknamed ‘Pau’ (Pierolapithecus catalaunicus), ‘Laia’ (Pliobates cataloniae) and ‘Lluc’ (Anoiapithecus brevirostris). Various studies of mammal remains recovered from the site, including the current work in eLife, indicate the existence of a dense subtropical forest.
Reference:
Isaac Casanovas-Vilar, Joan Garcia-Porta, Josep Fortuny, Óscar Sanisidro, Jérôme Prieto, Marina Querejeta, Sergio Llácer, Josep M Robles, Federico Bernardini, David M Alba. Oldest skeleton of a fossil flying squirrel casts new light on the phylogeny of the group. eLife, 2018; 7 DOI: 10.7554/eLife.39270
Note: The above post is reprinted from materials provided by eLife.
