Scientists investigate Grand Canyon's ancient past to predict future climate impacts

 The Grand Canyon's valleys and millions of years of rock layers spanning Earth's history have earned it a designation as one of the Seven Natural Wonders of the World. But, according to a new UNLV study, its marvels extend to vast cave systems that lie beneath the surface, which just might hold clues to better understand the future of climate change -- by studying nature's past.

A research team -- led by UNLV paleoclimatologist and professor Matthew Lachniet -- pulled an ancient stalagmite from the floor of an undisturbed Grand Canyon cave. By studying the mineral deposits' geochemistry, they were able to analyze precipitation patterns during the rapidly warming period following the last Ice Age to improve understanding about the potential impact of future climate change on summer monsoon rains in the U.S. Southwest and northwestern Mexico.

Their findings, published Oct. 2 in Nature Geoscience, revealed that increasing levels of water seeped into the cave between 8,500 and 14,000 years ago, during a period known as the early Holocene when temperatures rose throughout the region. Using a paleoclimate model, the researchers determined that this was likely caused by intensified and expanded summer rainfall stemming from atmospheric impacts on air circulation patterns that more quickly melted the winter snowpacks and sped up the evaporation process that fuels monsoon rains.

This is significant, authors say, because most of the water currently infiltrating through the bedrock and into caves and aquifers -- and contributing to groundwater recharge -- comes from winter snowmelt. During the early Holocene, however, when peak temperatures were only slightly warmer than today, both summer and winter moisture contributed to groundwater recharge in the region.

The authors suggest that future warming, which could cause temperatures to rise above those of the early Holocene, may also lead to greater rates of summer rainfall on the high-elevation Colorado Plateau and an intensifying North American monsoon, the pattern of pronounced and increased thunderstorms and precipitation that typically occur between June and mid-September.

"What was surprising about our results is that during this past warm period, both the summer monsoon and infiltration into the cave increased, which suggests that summer was important for Grand Canyon groundwater recharge, even though today it is not an important season for recharge," said Lachniet, who personally retrieved the stalagmite from a cave in the Redwall Formation on the South Rim of eastern Grand Canyon in 2017. "While we still expect the region to dry in the future, more intense summer rainfall may actually infiltrate into the subsurface more than it does today."

Stalagmites are common cave formations that act as ancient rain gauges that record historic climate change. They grow as mineral-rich waters seep through the ground above and drop from the tips of stalactites on cave ceilings. Calcite minerals from tiny drops of water accumulate over thousands of years and, much like tree rings, accurately record the rainfall history of an area. Three natural forms of oxygen are found in water, and the quantity of one form decreases as rainfall increases. This information is locked into the stalagmites over time.

Because of the distinct difference in the oxygen isotope composition between summer and winter precipitation, it is possible to estimate the relative contributions from each season. Variation in uranium-234 isotope and changes in the growth thickness of stalagmite give indication of the change in the amount of precipitation.

"We were able to validate the oxygen record with the growth data, with the uranium isotope data to confirm that in fact, we see significant increases in summer moisture during this warm period, which we attribute to the monsoon," said the University of New Mexico professor Yemane Asmerom. "Unfortunately, effective moisture is the balance between precipitation and evaporation. Unlike the more temperate Grand Canyon climate, the dry southern part, is likely to be drier, as a result of the increased temperatures."

The research team used stalagmite samples to reconstruct groundwater recharge rates -- or, the amount of water that penetrates the aquifers -- in the Grand Canyon area during the early years of the Holocene period. High groundwater recharge rates likely occurred on other high-elevation plateaus in the region, too, they said, though it's unclear how the activity applies to hotter, low-elevation deserts.

What is clear is that ongoing human-caused climate change is leading to hotter temperatures throughout southwestern North America, including the Grand Canyon region. Alongside population growth and agricultural pressures, this warming can reduce the infiltration of surface water into groundwater aquifers. Groundwater recharge rates also depend on the frequency and intensity of summer rains associated with monsoon season.

Though summer infiltration isn't a significant contributor to groundwater recharge in the region today, these latest findings suggest that could change in the future as the climate warms and monsoonal moisture increases. What's unknown is how a projected decrease in winter precipitation and snowpack could impact overall groundwater reserves.

Modelling of adhesive technology sheds new light on prehistoric cognition

 Studying prehistoric production processes of birch bark tar using computational modelling reveals what kinds of cognition were required for the materials produced by Neanderthal and early modern humans. Researchers of Team Langejans in the Materials Science and Engineering (MSE) department (TU Delft) recently published two papers on one of the world's oldest transformative technologies, publishing their findings in Nature Scientific Reports.

Measuring complexity

Birch bark tar is the first time we see evidence of creating a new material, said Dr. Paul Kozowyk, lead author on one of the papers. Examining the methods used to create the tar is an important step in understanding the behaviours and technical cognition required by the Neanderthals. Using Petri net models, a formal modelling language, Dr. Sebastian Fajardo led a study looking at various production methods, using metrics from existing literature to measure complexity. "Neanderthals used, at least on some occasions, a complex production process to make tar. To do that they needed ways to deal with a lot of information, like understanding and a way to transmit information very well," he said. The findings from the study suggest that Neanderthals probably relied on several cognitive traits that archaeologists often associate with modern thinking and behaviour.

Scaling up

Taking one of the metrics Fajardo used, Kozowyk applied it in more detail to one of the tar production techniques to explore how scaling up a technological process affects its complexity. "The outcome in this case was that it has a very significant impact on the complexity and that suggests people had a way to deal with this complex upscaling," he said. That might involve inventing a different method or working together as a group which requires more communication. "We don't prove that they were using a particular method, but our findings show that regardless of the methods employed, prehistoric tar making likely required a level of information processing that extended beyond simple behaviours."

Materials then and now

Archaeological research has found a niche at the TU Delft, and Fajardo said it all comes down to analysing materials. "For example, at 3mE we try to find new materials," he noted. "We try to understand how these new materials were produced in the past because if we understand how the first human-made materials were created, we can also start to identify human conditions we need to make new materials now with the resources that we have." For Kozowyk, whose research is mostly experimental, it's about looking at the material properties of the adhesives to try to understand the decisions that people made in the past. "A lot of my experiments involve mechanical testing of the materials so this is the right place to be."

Antarctica's glacial border migrates for miles with the tide

 The grounding line of the southern Ronne Ice Shelf in Antarctica can shift up to 15 km (six miles) with changing tides, new analysis shows. The research, published today in The Cryosphere, examines the key region where land-based Antarctic ice spills over into the surrounding ocean. Observing and understanding the dynamics of this region can help scientists predict Antarctica's response to climate change, and so how much global sea levels will rise.

"We typically think of ice sheet change as being very slow, taking place over decades, centuries or even millennia. But our findings highlight that there are some processes operating over minutes to hours that may have significant impacts," says Bryony Freer, lead author and glaciologist at the British Antarctic Survey and the Centre for Satellite Data in Environmental Science at the University of Leeds.

The location of Antarctica's grounding line -- the boundary between the land-based section of the ice sheet and the floating ice shelf -- helps control ice stability. During a rising tide, extra buoyancy lifts more of the ice shelf off the seabed and the grounding line temporarily moves inland. It returns to its seaward position at low tide.

Earlier measurements of such grounding line movement were restricted to small regions over short timescales. In the new study, the researchers monitored a large chunk of the Ronne Ice Shelf grounding line (220 km) for nearly five years.

Using lasers bounced off the ice from the orbiting satellite ICESat-2, the team could measure to within a few centimetres the height of the ice surface and how it rose and sank with daily tides. They used this information to calculate the changing position of the grounding line.

The 15 km shift in the grounding line position between high and low tide described in the new paper is the one of the largest observed anywhere in Antarctica. It shows the grounding line can move at more than 30 km per hour, flushing ocean water several kilometres further inland under the ice sheet.

This exposure to sea water could help the ice melt more quickly from below. In less stable Antarctic regions, such as the Thwaites Glacier, this process is known to have driven long-term historic grounding line retreat.

Grounding line movement depends on the tidal range, the shape of the seafloor and the strength of the ice. The new study found the grounding line in some regions moved inland much faster during a rising tide than it later returned as the tide dropped -- a particularly exciting finding according to the researchers. This is because it suggests that sea water may become trapped under the ice as the grounding line readvances and so takes longer to be flushed out, perhaps increasing the rate at which the ice sheet melts from below.

"It's vital that we improve both our observations and modelling of these tidal processes, to better understand how they operate and work out the likely implications for long-term ice sheet change," Freer says.

The researchers recommend that any future satellite-derived measurements of grounding line position should be timestamped to the nearest hour, along with tide height and phase. They also want to repeat the analysis across more of Antarctica.

Helen Amanda Fricker, ICESat-2 Science Team Leader and Professor at the Scripps Institution of Oceanography in California, and paper co-author says:

"This work showcases how the unprecedented sampling in both space and time of ICESat-2 can reveal new information about dynamic features on ice shelves. It is critical that we continue these measurements with future missions."

Tree rings reveal a new kind of earthquake threat to the Pacific Northwest, US

 In February, a 7.8-magnitude earthquake shook the Turkey-Syria border, followed by one nearly as large nine hours later. Shallow faults less than 18 miles beneath the surface buckled and ruptured, causing violent focused quakes that leveled thousands of buildings and killed tens of thousands.

Similar shallow faults ruptured about 1,000 years ago in the Puget Lowlands in western Washington, according to new University of Arizona-led research. Tree rings helped pinpoint that the seismic event occurred in late A.D. 923 or early 924. Their findings mean that a repeat event has the potential to again shake the region that is now home to over 4 million people, including Seattle, Tacoma and Olympia. The results were published in the journal Science Advances.

The ancient quake was either the result of all the shallow faults in the region rupturing together to produce an estimated 7.8-magnitude earthquake or -- like in Turkey and Syria -- twin quakes that occurred back-to-back with estimated magnitudes of 7.5 and 7.3, researchers found. Shallow faults typically result in more violent and focused shaking than earthquakes generated from other geological configurations.

While earthquakes are not new to the Pacific Northwest, the study identified that events on these shallow faults are linked to each other in some way, either by connections underground or by one fault transferring stress to the other. Regional hazard models, used to develop engineering design and policies, don't currently reflect this possibility -- but should, said paper first author Bryan Black, an associate professor of dendrochronology in the UArizona Laboratory for Tree-Ring Research.

Homing in on the millennial cluster

Scientists have been uncovering shallow faults in the region since the 1960s, when the Seattle Fault was first discovered, followed by the Saddle Mountain Fault, which runs along the eastern foothills of the Olympic Mountains, and the Tacoma and Olympia faults.

"These are four shallow faults that had shown evidence of having ruptured roughly 1,000 years ago in a cluster of earthquakes called the millennial cluster," Black said. For example, "a 25-foot cliff was thrusted into the air from west Seattle out to Puget Sound. It also triggered a local tsunami and landslides that stripped mountainsides of whole forests and discarded them into nearby lakes Washington and Sammamish."

Until now, scientists weren't clear on exactly when and how these faults last gave out.

"These quakes could have ruptured at the same time, hours apart or centuries apart," Black said. "We weren't sure."

So, he turned to the trees.

Diving deep

With each passing year, trees add a ring around their trunks. The ring width is determined by the climate they experience. Favorable conditions mean wider rings and unfavorable conditions mean thinner. As climate varies from year to year, it creates time-specific patterns like a bar code in the growth of trees within a region.

Dendrochronologists can match these time-specific growth patterns in dead trees with patterns from living trees. If there is overlap with living trees, the exact dates over which the dead trees lived -- and died -- can be established. This was the approach used to determine when the earthquake-killed trees died in the Puget Sound region.

In 2021, Black trekked into the mountains of the Pacific Northwest to participate in harvesting stumps from trees that had died when the Saddle Mountain Fault impounded a stream that flooded a forest. The lake and the stumps of these drowned trees remain today.

The team strapped two canoes together and slapped a large piece of plywood atop them both to create a makeshift barge that would hold a generator to power underwater chainsaws. With these in hand, divers leaped into the water to cut samples of trees killed when the lake formed from the millennial cluster. Black and his team also had sections sourced from nearby trees killed around the same time during a rock avalanche that impounded a stream that flooded a nearby streambed. They also acquired sections from trees collected more than 30 years ago that had drowned in landslides into Lake Washington and Lake Sammamish during a large earthquake on the Seattle Fault.

When he compared the growth patterns, Black observed that the trees died the exact same year across both the Saddle Mountain and Seattle faults. He also saw that the trees died during their dormant season, which narrows the time of death -- and the earthquake by extension -- to the late fall through early spring.

To determine an exact calendar year of death, the team built a 1,300-year chronology from living but extremely old trees, which, when matched with the earthquake-killed trees, showed that the dormant season of death was late 923 to early 924.

"Our team was also lucky that there was a massive solar storm between the years 774 and 775, which caused a sudden global spike in radiocarbon," said associate professor of dendrochronology and co-author Charlotte Pearson. Radiocarbon fluctuations, like climate, can be used to date tree rings. "We measured radiocarbon in the rings of earthquake-killed trees to show that this spike occurred right where we thought it should."

This independently confirmed their earthquake date.

"Combined, the evidence showed us that these trees from across the region died together, and this was in fact a linked event," Black said. "We've taken uncertainties around these two faults that used to span decades or centuries and narrowed it down to within one season. It's a much different scenario if we have earthquakes on these two faults separated by 100 years versus 100 hours. Demonstrating that these faults can rupture synchronously or in very rapid succession has really changed what we understand about the hazard in the region."

Yet, current hazard models don't currently recognize that linked faulting is possible, he said.

"If Saddle Mountain and Seattle faults went together it would be on par with the 1906 earthquake in San Francisco," Black said. "Or, like the quakes in Turkey, they can also go at rapid succession. If that were the case, the infrastructure and landforms already weakened by one quake are then going to get the knockout punch with a second quake. It will still be quite destructive: thrusting up water mains, severing roads, triggering landslides and local tsunamis."

Luckily, he said, the bigger and more severe the quake, the less frequent it is. So, while quakes of this size would be devastating to the region, they are relatively uncommon.

Then vs. now: Did the Horn of Africa reach a drought tipping point 11,700 years ago?

 New research suggests that the Horn of Africa is likely to become even drier, not wetter in the future as predicted by most climate models.

'Wet gets wetter, dry gets drier'. That mantra has been used for decennia to predict how global warming will affect the hydrological cycle in different world regions. But if climate models predict that much of tropical Africa will enjoy a future with wetter weather, then why does it keep getting drier in certain parts of the African tropics, like the Horn of Africa? An international team of researchers have found a pre-historic climate tipping point that helps explain the disparity between these model predictions and the intensifying drought conditions in the Horn of Africa. Their new study was published in the scientific journal Nature on 10 August.

Moisture equals rainfall minus evaporation

Simply put, two main things make up how wet or dry an environment is: the amount of rainfall, and the amount of water that evaporates from the land and plants. In the tropics, higher temperatures typically bring along wetter weather due to stronger monsoons. At the same time, higher temperatures also cause more evaporation since in warmer air, water evaporates more easily.

And yet, recently parts of the world like the Horn of Africa have seen severe multi-year droughts with rising temperatures. A research team including lead co-authors Allix Baxter (Utrecht University) and Dirk Verschuren (Ghent University) have found an explanation for the disparity between climate model predictions and recent droughts in eastern Africa in the sediments of Lake Chala, located on the Kenya/Tanzania border near Mount Kilimanjaro.

Climate tipping point

"We found that, during the last ice age between 75,000 and 11,700 years ago, higher temperatures in the Horn of Africa did indeed produce a wetter climate," Verschuren explains. "But around 11,700 years ago, when the region's temperature naturally rose by a few degrees, we saw a tipping point in which higher temperatures led to increased drought, and lower temperatures meant wetter conditions." This fundamental change in the relationship between temperature and moisture in the Horn of Africa, has since locked this region into a dry tropical climate regime, which the researchers expect to continue as temperatures keep rising in the future.

"This finding matches with the increasing number and severity of droughts we now see happening in the Horn of Africa," Baxter illustrates. Quite importantly for this region where most people depend on rain-fed agriculture, the new research suggests that the Horn of Africa is likely to become even drier, not wetter in the future as predicted by most climate models. "Though it's still debated what the cause is of these recent droughts, our research provides the clue to an underlying mechanism. Our data has revealed certain processes that we hope are better incorporated in the climate models to more accurately predict long-term future climate change in this and other tropical regions."

Fossil feces infested with parasites from over 200 million years ago

 Fossilized feces preserve evidence of ancient parasites that infected an aquatic predator over 200 million years ago, according to a study published August 9, 2023 in the open-access journal PLOS ONE by Thanit Nonsrirach of Mahasarakham University, Thailand and colleagues.

Parasites are a common and important component of ecosystems, but ancient parasites are difficult to study due to a poor fossil record. Parasites often inhabit the soft tissues of their host, which rarely preserve as fossils. There are, however, cases where traces of parasites can be identified within fossilized feces (coprolites). In this study, Nonsrirach and colleagues describe evidence of parasites in a Late Triassic coprolite from the Huai Hin Lat Formation of Thailand, which is over 200 million years old.

The coprolite is cylindrical in shape and over 7cm long. Based on its shape and contents, the researchers suggest it was likely produced by some species of phytosaur, crocodile-like predators which are also known from this fossil locality. Microscopic analysis of thin sections of the coprolite revealed six small, round, organic structures between 50-150 micrometers long. One of these, an oval-shaped structure with a thick shell, is identified as the egg of a parasitic nematode worm, while the others appear to represent additional worm eggs or protozoan cysts of unclear identity.

This is the first record of parasites in a terrestrial vertebrate host from the Late Triassic of Asia, and a rare glimpse into the life of an ancient animal that was apparently infected by multiple parasitic species. This discovery also adds to the few known examples of nematode eggs preserved within the coprolites of Mesozoic animals. These findings are therefore a significant contribution to scientific understanding of the distribution and ecology of parasites of the distant past.

The authors add: "Coprolite is a significant paleontological treasure trove, containing several undiscovered fossils and expanding our understanding of ancient ecosystems and food chains."

Bees evolved from ancient supercontinent, diversified faster than suspected

 The first bees evolved on an ancient supercontinent more than 120 million years ago, diversifying faster and spreading wider than previously suspected, a new study shows.

Led by Washington State University researchers, the study provides a new best estimate for when and where bees first evolved. Newly published in the journal Current Biology, the project reconstructed the evolutionary history of bees, estimated their antiquity, and identified their likely geographical expansion around the world.

The results indicate their point of origin was in western Gondwana, an ancient supercontinent that at that time included today's continents of Africa and South America.

"There's been a longstanding puzzle about the spatial origin of bees," said Silas Bossert, assistant professor with WSU's Department of Entomology, who co-led the project with Eduardo Almeida, associate professor at the University of São Paulo, Brazil.

Working with a global team, Bossert and Almeida's team sequenced and compared genes from more than 200 bee species. They compared them with traits from 185 different bee fossils, as well as extinct species, developing an evolutionary history and genealogical models for historical bee distribution. In what may be the broadest genomic study of bees to date, they analyzed hundreds to thousands of genes at a time to make sure that the relationships they inferred were correct.

"This is the first time we have broad genome-scale data for all seven bee families," said co-author Elizabeth Murray, a WSU assistant professor of entomology.

Previous research established that the first bees likely evolved from wasps, transitioning from predators to collectors of nectar and pollen. This study shows they arose in arid regions of western Gondwana during the early Cretaceous period.

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"For the first time, we have statistical evidence that bees originated on Gondwana," Bossert said. "We now know that bees are originally southern hemisphere insects."

The researchers found evidence that as the new continents formed, bees moved north, diversifying and spreading in a parallel partnership with angiosperms, the flowering plants. Later, they colonized India and Australia. All major families of bees appeared to split off prior to the dawn of the Tertiary period, 65 million years ago -- the era when dinosaurs became extinct.

The tropical regions of the western hemisphere have an exceptionally rich flora, and that diversity may be due to their longtime association with bees, authors noted. One quarter of all flowering plants belong to the large and diverse rose family, which make up a significant share of the tropical and temperate host plants for bees.

Bossert's team plans to continue their efforts, sequencing and studying the genetics and history of more species of bees. Their findings are a useful first step in revealing how bees and flowering plants evolved together. Understanding how bees spread and filled their modern ecological niches could also help keep pollinator populations healthy.

"People are paying more attention to the conservation of bees and are trying to keep these species alive where they are," Murray said. "This work opens the way for more studies on the historical and ecological stage."

Additional contributors included Felipe Freitas, Washington State University; Bryan Danforth, Cornell University; Charles Davis, Harvard University; Bonnie Blaimer, Tamara Spasojevic, and Seán Brady, Smithsonian Institution; Patrícia Ströher and Marcio Pie, Federal University of Paraná, Brazil; Michael Orr, State Museum of Natural History, Stuttgart; Laurence Packer, York University; Michael Kuhlmann, University of Kiel; and Michael G. Branstetter, U.S. Department of Agriculture.

Insolation affected ice age climate dynamics

 In past ice ages, the intensity of summer insolation affected the emergence of warm and cold periods and played an important role in triggering abrupt climate changes, a study by climate researchers, geoscientists, and environmental physicists suggests. Using stalagmites in the European Alps, they were able to demonstrate that warm phases appeared primarily when the summer insolation reached maxima in the Northern Hemisphere. Study participants included scientists from Germany, Austria, and Switzerland led by researchers from Heidelberg University and the GFZ German Research Centre for Geosciences Potsdam.

Past ice ages in the Northern Hemisphere were marked by sudden transitions between cold and warm phases, each lasting several thousand years. The reason for these fluctuations has yet to be resolved, but research does point to effects relating to the size of the continental ice sheets. Greenland ice records 25 such warm-cold cycles between 115,400 and 14,700 years ago. Investigating stalagmites in the Melchsee-Frutt cave system in the Swiss Alps, the researchers were able to investigate for the first time and with high precision 16 such fluctuations in the penultimate glacial period 185,000 to 130,000 years ago.

Stalagmites in caves are crucial archives in climate research and offer clues as to changes in temperature, precipitation, and vegetation cover. "We are able to precisely determine their age and hence analyse the chronological sequence of abrupt ice age climate fluctuations, which we identify using oxygen isotope values," explains Prof. Dr Norbert Frank of the Institute of Environmental Physics at Heidelberg University. "Our investigations targeted whether, in addition to ice volumes in the Northern Hemisphere, orbitally driven changes in the global distribution of insolation could have influenced the abrupt changes in climate," states study head Dr Jens Fohlmeister, who earned his doctorate in environmental physics at Heidelberg University and worked at the GFZ German Research Centre for Geosciences Potsdam and the Potsdam Institute for Climate Impact Research during the investigations.

The researchers studied the transitions of warm-cold cycles in the penultimate ice age by analysing the age and oxygen isotope composition of stalagmites from the Melchsee-Frutt cave system. "Based on the newly acquired data, we were able to show that warm phases occurred mainly during the peak phase of summer insolation in the Northern Hemisphere, even when the sea level, which is dependent on the volume of the continental ice sheets, remained close to its minimum during peak glacial periods," explains Dr Fohlmeister. Model simulations confirmed these findings. In accordance with the research data from the cave system, the simulations predict the frequency as well as the duration of warm phases at the corresponding sea level and existing insolation.

Scientists from the Potsdam Institute for Climate Impact Research, the GFZ German Research Centre for Geosciences Potsdam, Heidelberg University, the University of Innsbruck (Austria), the Swiss Institute for Speleology and Karst Studies, and the Karst and Caves Natural Heritage Foundation Obwalden (Switzerland) participated in the study. The research was funded by the German Research Foundation. The results were published in the journal "Communications Earth & Environment."

Using gemstones' unique characteristics to uncover ancient trade routes

 Since ancient times, gemstones have been mined and traded across the globe, sometimes traveling continents from their origin. Gems are geologically defined as minerals celebrated for beauty, strength, and rarity. Their unique elemental composition and atomic orientation act as a fingerprint, enabling researchers to uncover the stones' past, and with it, historical trade routes.

In AIP Advances, from AIP Publishing, Khedr et al. employed three modern spectroscopic techniques to rapidly analyze gems found in the Arabian-Nubian Shield and compare them with similar gems from around the world. Using laser-induced breakdown spectroscopy (LIBS), Fourier transform infrared (FTIR) spectroscopy, and Raman spectroscopy, the authors identified elements that influence gems' color, differentiated stones found within and outside the region, and distinguished natural from synthetic.

The Arabian-Nubian Shield is an exposure of mineral deposits that sandwiches the Red Sea in current-day Egypt and Saudi Arabia. The deposits date back to the Earth's earliest geological age, and the precious metals and gemstones have been harvested for thousands of years.

"We showed the main spectroscopic characteristics of gemstones from these Middle East localities to distinguish them from their counterparts in other world localities," said author Adel Surour. "This includes a variety of silicate gems such as emerald from the ancient Cleopatra's mines in Egypt, in addition to amethyst, peridot, and amazonite from other historical sites, which mostly date to the Roman times."

The various spectroscopic techniques they employed revealed different information about the stones. LIBS quickly characterizes chemical composition, while FTIR determines functional groups connected to the structure and indicates the presence of water and other hydrocarbons. Even for chemically identical materials, Raman spectroscopy shows the unique crystalline structure of the gems' atoms.

The authors identified that iron content correlates to amethysts' signature purple hue, and other elements such as copper, chromium, and vanadium are also responsible for colorization. A signature water peak exposes lab-grown synthetic gems, which are useful for scientific purposes and identical to natural gems but are less expensive.

Crystalline structure differentiated amazonite beads from Mexico, Jordan, and Egypt.

"Gemstones such as emerald and peridot have been mined since antiquity," Surour said. "Sometimes, some gemstones were brought by sailors and traders to their homelands. For example, royal crowns in Europe are decorated with peculiar gemstones that originate from either Africa or Asia. We need to have precise methods to distinguish the source of a gemstone and trace ancient trade routes in order to have correct information about the original place from which it was mined."

North Atlantic Oscillation contributes to 'cold blob' in Atlantic Ocean

 A patch of ocean in the North Atlantic is stubbornly cooling while much of the planet warms. This anomaly -- dubbed the "cold blob" -- has been linked to changes in ocean circulation, but a new study found changes in large-scale atmospheric patterns may play an equally important role, according to an international research team led by Penn State.

"People often think the atmosphere has a very short memory, but here we provide evidence that atmospheric circulation change is significant enough to induce some long-term impact on the climate system," said corresponding author Laifang Li, assistant professor of meteorology and atmospheric science at Penn State.

Sea surface temperatures in the subpolar North Atlantic have decreased by about .7 degrees Fahrenheit over the last century, and a trend toward a more frequent positive phase of the North Atlantic Oscillation (NAO) may have contributed significantly, the scientists reported in the journal Climate Dynamics.

The NAO represents atmospheric circulation patterns involving a low-pressure system near Iceland and a high-pressure system near the Azores Islands, and it influences how westerly winds blow across the ocean. In the positive phase, both pressure systems are stronger than average, resulting in a stronger jet stream and a northward shift of the westerly winds, the scientists said.

"As the NAO becomes more positive, it intensifies the surface wind over the subpolar North Atlantic," said Li, who is also an associate of the Earth and Environmental Systems Institute and a co-hire of the Institute for Computational and Data Sciences at Penn State. "When we would like to cool a cup of hot coffee, we stir the surface, and it promotes heat loss. That's exactly what wind intensification is going to do to the ocean surface -- it provides a direct cooling effect."

The team analyzed weather data and found the positive NAO has become more dominant during the past century, consistent with previous research. This shift could be due to warming of the tropical Indo-Pacific and sea ice loss in the Labrador Sea, according to the researchers, but its exact causes remain an open question.

Using an idealized model, the researchers isolated the role that this increased wind may play in reducing sea surface temperatures via air-sea heat flux.

"We know the atmosphere can not only force surface temperature change but also can passively respond to the surface temperature change itself -- we call this forcing and damping," said Yifei Fan, a doctoral candidate at Penn State and lead author on the study. "Our model separates these two processes and can quantify the impact of wind on the surface turbulent heat flux and thus the resultant sea surface temperature changes."

The NAO alone could explain 67% of the sea surface temperature cooling trend, the scientists said. But other atmospheric patterns that have a warming effect may partially offset this, decreasing the overall impact of atmospheric circulation changes to 44%. Those findings are consistent with previous estimations from the group.

The findings suggest, the researchers said, that the NAO may have an equally important role in the cold blob as the Atlantic Meridional Overturning Circulation -- or AMOC -- ocean currents that carry warm water from the tropics north to the North Atlantic like a conveyor belt. Other studies have suggested the sea surface cooling is a sign the conveyor belt is weakening.

"Previous studies have focused mostly on the role of ocean circulation in transporting heat to this region," Fan said. "Our study, based on observations, quantifies the role of atmospheric circulation change to the cold blob. And that's important because few existing studies have focused on atmospheric circulation contributing to this long-term change in sea surface temperature."

The results, however, should not be interpreted as a line of evidence against the role of oceanic processes, which also likely play a large role in the cooling, according to the scientists. But atmospheric circulation change should also be considered moving forward.

"Here we do provide evidence that there is no one-to-one relationship between sea surface temperature change and overturning circulation change," Li said. "So we should be very careful when extrapolating this overturning circulation change or great conveyor belt change from sea surface temperature alone."

The scientists said a better understanding of the unique cold blob region is important because of its potential climate impacts.

"Once you have temperature cooling set up over the subpolar North Atlantic, it increases the instability in the atmosphere and favors the passage of storms that can come across the ocean basin and bring extreme weather events to North America and Europe," Li said. "This might add another layer of complexity to projections of future high-impact weather events and uncertainties to climate projections for heavily populated areas."

Wei Liu, associate professor at the University of California, Riverside; Ru Chen, professor at Tianjin University, China; and Pengfei Zhang, assistant research professor at Penn State, also contributed to this work.

A seed grant from the Penn State Institute for Computational and Data Sciences supported this work. Researchers on the project received support from the National Science Foundation and the National Natural Science Foundation of China.

Life on Earth didn't arise as described in textbooks

 No, oxygen didn't catalyze the swift blossoming of Earth's first multicellular organisms. The result defies a 70-year-old assumption about what caused an explosion of oceanic fauna hundreds of millions of years ago.

Between 685 and 800 million years ago, multicellular organisms began to appear in all of Earth's oceans during what's known as the Avalon explosion, a forerunner era of the more famed Cambrian explosion. During this era, sea sponges and other bizarre multicellular organisms replaced small single-celled amoeba, algae and bacteria, which until then, had had run of the planet for more than 2 billion years.

Up until now, it was believed that increased oxygen levels triggered the evolutionary arrival of more advanced marine organisms. This is being disproved by University of Copenhagen researchers working together with colleagues from Woods Hole Oceanographic Institute, the University of Southern Denmark and Lund University, among others.

By studying the chemical composition of ancient rock samples from an Omani mountain range, the researchers have been able to "measure" oxygen concentrations in the world's oceans from when these multicellular organisms appeared. Defying expectations, the result shows that Earth's oxygen concentrations had not increased. Indeed, levels remained 5-10 times lower than today, which is roughly how much oxygen there is at twice the height of Mount Everest.

"Our measurements provide a good picture of what average oxygen concentrations were in the world's oceans at the time. And it's apparent to us that there was no major increase in the amount of oxygen when more advanced fauna began to evolve and dominate Earth. In fact, there was somewhat of a slight decrease," says Associate Professor Christian J. Bjerrum, who has been quantifying the conditions surrounding the origin of life for the past 20 years.

Revises our understanding of life's origins

The new result puts to rest a 70-year research story that advances the centrality of higher oxygen concentrations in the development of more advanced life on our planet.

"The fact that we now know, with a high degree of certainty, that oxygen didn't control the development of life on Earth provides us with an entirely new story about how life arose and what factors controlled this success," says the researcher, adding:

"Specifically, it means that we need to rethink a lot of the things that we believed to be true from our childhood learning. And textbooks need to be revised and rewritten."

There remains much that the researchers don't know, as well as and a plethora of controversy. Therefore, Bjerrum hopes that the new result can spur other researchers around the world to reconsider their previous results and data in a new light.

"There are many research sections around the world, including in the United States and China, that have done lots of research on this topic, whose earlier results may shed important new details if interpreted on the basis that oxygen didn't drive the development of life," says the researcher.

Absence of oxygen may have aided development

So, if not extra oxygen, what triggered the era's explosion of life? Perhaps the exact opposite, explains the researcher:

"It's interesting that the explosion of multicellular organisms occurs at a time with low concentrations of atmospheric and oceanic oxygen. That indicates that organisms benefited from lower levels of oxygen and were able to develop in peace, as the water chemistry protected their stem cells naturally," says Christian J. Bjerrum.

According to the researcher, the same phenomenon has been studied in cancer research, in the stem cells of humans and other animals. Here, colleagues at Lund University observed that low oxygen levels are crucial for keeping stem cells under control until an organism decides that the cell ought to develop into a specific type of cell, such as a muscle cell.

"We know that animals and humans must be able to maintain low concentrations of oxygen in order to control their stem cells, and in so doing, develop slowly and sustainably. With too much oxygen, the cells will develop, and in the worst case, mutate wildly and perish. It is far from inconceivable that this mechanism applied back then," concludes Christian J. Bjerrum.

Fossils from Oman

In the new study, the researchers analysed rock samples from, among other places, the Oman Mountains in northern Oman. While quite high and very dry today, the mountains were on the seabed during the Avalon explosion's rapid blossoming of organism diversity.

The researchers have had their findings confirmed in fossils from three different mountain ranges around the world: the Oman Mountains (Oman), Mackenzie Mountains (NW Canada) and the Yangtze Gorges area of South China.

Over time, clay and sand from land are washed into the sea, where they settle into layers on the seabed. By going down through these layers and examining their chemical composition, researchers can get a picture of ocean chemistry at a particular geologic time.

The analyses were performed using Thallium and Uranium isotopes found in the mountains, which the researchers were able to extract data from, and in doing so, calculate oxygen levels from many hundreds of millions of years ago.

Flying reptiles had nurturing parental style

 Did the pterosaurs, flying reptiles from the days of the dinosaurs, practice parental care or not? New research by scientists from Ireland (University College Cork), China (Nanjing and Yunnan Universities) and the UK (University of Bristol and Queen Mary University of London) shows that pterosaurs were indeed caring parents -- but only the larger species.

This solves a long-standing conundrum. To be able to fly soon after hatching from the egg, a bird or pterosaur must have well-developed wings. Studies of smaller pterosaurs from the Jurassic showed that their babies already had large wings when they hatched and they could have wobbled into flight within a few days of birth.

But did this work for the later pterosaurs which were much larger in size? In the Cretaceous, pterosaurs usually had wingspans of 5 metres, and some even reached 10-15 metres, the size of a small glider.

"This was a difficult project," says the study leader, Dr Zixiao Yang from University College Cork (UCC). 'We needed examples of pterosaurs where we had at least one hatchling or very young specimen as well as adults so we could study their growth rates. But baby pterosaurs are really rare."

Dr Yang collaborated with Professor Baoyu Jiang from Nanjing University, Professor Michael Benton of University of Bristol, Professor Xu Xing of Yunnan University, and Professor Maria McNamara of UCC on the research.

"Luckily, we were able to use some classic specimens from the Jurassic of Europe and the Cretaceous of North America, together with new finds from China. By measuring the skulls, backbones, wings, and hind legs, we were able to test for differences in the relative growth of different parts of the body."

The research focussed on testing the allometry, or how the creatures' characteristics changed with size.

"We are all familiar with allometry in human babies, puppies and kittens -- their heads, eyes and knees are huge, and the rest of the body grows faster to get to adult proportions. It's the same with many animals, including dinosaurs and pterosaurs. The babies have cute faces, with short noses, big eyes, and big heads," Dr Yang said.

"The small, bird-sized, Jurassic pterosaurs were born with large wings and strong arms and legs, evidence that the babies could fly from birth. As they grew from baby to adult, their arms and legs showed negative allometry, meaning they started large and were then growing more slowly than the rest of the body."

"But it was different for the Cretaceous giants. They also started as small babies, but the key limb bones show positive allometry through growth, suggesting a very different developmental model."

"This means that the pterosaur giants had sacrificed low-input childcare to the need to grow huge eventually as adults. Minimal childcare makes sense in the early evolutionary history of these ancient reptiles because it saves energy. But to grow huge, the larger pterosaurs had a problem -- it basically took much longer to become an adult, and therefore parents needed to protect their young from accidents. The babies of all pterosaurs, large and small, were small because of the limitations of egg size. Investing in childcare by having non-flying babies was offset in evolutionary terms by allowing pterosaurs to evolve truly huge sizes."

"We see the same thing in birds and mammals today. Some birds fly very young, and of course some mammals like cattle and antelopes are on their feet the day they are born. But this kind of behaviour is risky for the babies because they are often clumsy and are easy targets for predators; it's costly also for the mother because the babies must have highly developed wings or legs at the point of birth. So, we see the same thing in extinct pterosaurs. They were restricted in maximum body size until the end of the Jurassic, at which point their parental care behaviour changed, and then they could achieve huge sizes."

Early humans were weapon woodwork experts, study finds

 A 300,000-year-old hunting weapon has shone a new light on early humans as woodworking masters, according to a new study.

State-of-the-art analysis of a double-pointed wooden throwing stick, found in Schöningen in Germany three decades ago, shows it was scraped, seasoned and sanded before being used to kill animals. The research indicates early humans' woodworking techniques were more developed and sophisticated than previously understood.

The findings, published today (Wednesday, 19 July) in PLOS ONE, also suggest the creation of lightweight weapons may have enabled group hunts of medium and small animals. The use of throwing sticks as hunting aids could have involved the entire community, including children.

Dr Annemieke Milks, of the University of Reading's Department of Archaeology, led the research. She said: "Discoveries of wooden tools have revolutionised our understanding of early human behaviours. Amazingly these early humans demonstrated an ability to plan well in advance, a strong knowledge of the properties of wood, and many sophisticated woodworking skills that we still use today.

"These lightweight throwing sticks may have been easier to launch than heavier spears, indicating the potential for the whole community to take part. Such tools could have been used by children while learning to throw and hunt."

Co-author Dirk Leder said: "The Schöningen humans used a spruce branch to make this aerodynamic and ergonomic tool. The woodworking involved multiple steps including cutting and stripping off the bark, carving it into an aerodynamic shape, scraping away more of the surface, seasoning the wood to avoid cracking and warping, and sanding it for easier handling."

High-impact weapon

Found in 1994, the 77cm-long stick is one of several different tools discovered in Schöningen, which includes throwing spears, thrusting spears and a second similarly sized throwing stick.

The double-pointed throwing stick -- analysed to an exceptionally high level of detail for this new study -- was most likely used by early humans to hunt medium-sized game like red and roe deer, and possibly fast-small prey including hare and birds that were otherwise difficult to catch. The throwing sticks would have been thrown rotationally -- similar to a boomerang -- rather than overhead like a modern-day javelin and may have enabled early humans to throw as far as 30 metres. Although lightweight, the high velocities at which such weapons can be launched could have resulted in deadly high-energy impacts.

The fine surface, carefully shaped points and polish from handling suggest this was a piece of personal kit with repeated use, rather than a quickly made tool that was carelessly discarded.

Principal investigator Thomas Terberger said: "The systematic analysis of the wooden finds of the Schöningen site financed by German Research Foundation provides valuable new insights and further exciting information on these early wooden weapons can be expected soon."

The well-preserved stick is on display at the Forschungsmuseum in Schöningen.

Paleontologists identify two new species of sabertooth cat

 Sabertooth cats make up a diverse group of long-toothed predators that roamed Africa around 6-7 million years ago, around the time that hominins -- the group that includes modern humans -- began to evolve. By examining one of the largest global Pliocene collections of fossils in Langebaanweg, north of Cape Town in South Africa, researchers present two new sabertooth species and the first family tree of the region's ancient sabertooths on July 20 in the journal iScience. Their results suggestthat the distribution of sabertooths throughout ancient Africa might have been different than previously assumed, and the study provides important information about Africa's paleoenvironment.

"The known material of sabertooths from Langebaanweg was relatively poor, and the importance of these sabertoothed cats has not been properly recognized," says senior author Alberto Valenciano, a paleontologist at Complutense University. "Our phylogenetic analysis is the first one to take Langebaanweg species into consideration."

The study described a total of four species. Two of these species, Dinofelis werdelini and Lokotunjailurus chimsamyae, were previously unknown. Dinofelis sabertooths are globally distributed, and their fossils have been found in Africa, China, Europe, and North America. The researchers were expecting to identify a new Dinofelis species from Langebaanweg based on prior research. However, Lokotunjailurus has only ever been identified in Kenya and Chad before this analysis. This suggests that they may have been distributed all throughout Africa between 5-7 million years ago.

Valenciano was a postdoctoral fellow at the Iziko Museums of South Africa, which houses all the sabertooth fossils that were analyzed in this study. A team of colleagues from China, South Africa, and Spain put the final project together. To construct a family tree, the researchers classified the physical traits of each sabertooth species -- such as presence or absence of teeth, jaw and skull shape, and tooth structure -- and coded this information into a matrix that could determine how closely related each sabertooth was to its evolutionary cousins.

The resulting population composition of Langebaanweg sabertooths (Machairodontini, Metailurini, and Feline) reflects the increasing global temperatures and environmental changes of the Pliocene epoch. For instance, the presence of Machairodontini cats, which are larger in size and more adapted to running at high speeds, suggests that there were open grassland environments at Langebaanweg. However, the presence of the Metailurini cats suggests that there were also more covered environments, such as forests. While the fact that researchers found both Metailurine and Machairodonti species suggests that Langebaanweg contained a mixture of forest and grassland 5.2 million years ago, the high proportion of Machairodonti species compared with other fossil localities from Eurasia and Africa confirm that southern Africa was transitioning toward more open grasslands during this period.

"The continuous aridification throughout the Mio-Pliocene, with the spread of open environments, could be an important trigger on the bipedalism of hominids," the authors write. "The sabertooth guild in Langebaanweg and its environmental and paleobiogeographic implications provide background for future discussion on hominid origination and evolution."

Interestingly, the researchers also note that the composition of sabertooths in Langebaanweg closely mirrors that of Yuanmou, China. Yuanmou's Longchuansmilus sabertooths might even have a close evolutionary relationship with Africa's Lokotunjailurus species.

"This suggests that the ancient environment of the two regions was similar or that there was a potential migration route between the Langebaanweg and Yuanmou," says first author Qigao Jiangzuo, a paleontologist at Peking University.

More fossil evidence could help paleontologists understand exactly how these two sites are related. "The two new sabertooths are only an example of the numerous unpublished fossils from Langebaanweg housed at Iziko in the Cenozoic Collections," says Romala Govender, a curator and paleontologist at the Iziko Museums in South Africa. "This brings to the fore the need for new and detailed studies of Langebaanweg fauna."

Oldest evidence of the controlled use of fire to cook food, researchers report

Wood fire burning

A remarkable scientific discovery has been made by researchers from the Hebrew University of Jerusalem (HU), Tel Aviv University (TAU), and Bar-Ilan University (BIU), in collaboration with the Steinhardt Museum of Natural History, Oranim Academic College, the Israel Oceanographic and Limnological Research (IOLR) institution, the Natural History Museum in London, and the Johannes Gutenberg University in Mainz. A close analysis of the remains of a carp-like fish found at the Gesher Benot Ya'aqov (GBY) archaeological site in Israel shows that the fish were cooked roughly 780,000 years ago. Cooking is defined as the ability to process food by controlling the temperature at which it is heated and includes a wide range of methods. Until now, the earliest evidence of cooking dates to approximately 170,000 years ago. The question of when early man began using fire to cook food has been the subject of much scientific discussion for over a century. These findings shed new light on the matter and was published in Nature Ecology and Evolution.

The study was led by a team of researchers: Dr. Irit Zohar, a researcher at TAU's Steinhardt Museum of Natural History and curator of the Beit Margolin Biological Collections at Oranim Academic College, and HU Professor Naama Goren-Inbar, director of the excavation site. The research team also included Dr. Marion Prevost at HU's Institute of Archaeology; Prof. Nira Alperson-Afil at BIU's Department for Israel Studies and Archaeology; Dr. Jens Najorka of the Natural History Museum in London; Dr. Guy Sisma-Ventura of the Israel Oceanographic and Limnological Research Institute; Prof. Thomas Tütken of the Johannes Gutenberg University in Mainz and Prof. Israel Hershkovitz at TAU's Faculty of Medicine.

Dr. Zohar and Dr. Prevost: "This study demonstrates the huge importance of fish in the life of prehistoric humans, for their diet and economic stability. Further, by studying the fish remains found at Gesher Benot Ya'aqob we were able to reconstruct, for the first time, the fish population of the ancient Hula Lake and to show that the lake held fish species that became extinct over time. These species included giant barbs (carp like fish) that reached up to 2 meters in length. The large quantity of fish remains found at the site proves their frequent consumption by early humans, who developed special cooking techniques. These new findings demonstrate not only the importance of freshwater habitats and the fish they contained for the sustenance of prehistoric man, but also illustrate prehistoric humans' ability to control fire in order to cook food, and their understanding the benefits of cooking fish before eating it."

In the study, the researchers focused on pharyngeal teeth (used to grind up hard food such as shells) belonging to fish from the carp family. These teeth were found in large quantities at different archaeological strata at the site. By studying the structure of the crystals that form the teeth enamel (whose size increases through exposure to heat), the researchers were able to prove that the fish caught at the ancient Hula Lake, adjacent to the site, were exposed to temperatures suitable for cooking, and were not simply burned by a spontaneous fire.

Until now, evidence of the use of fire for cooking had been limited to sites that came into use much later than the GBY site -- by some 600,000 years, and ones most are associated with the emergence of our own species, homo sapiens.

Prof. Goren-Inbar added: "The fact that the cooking of fish is evident over such a long and unbroken period of settlement at the site indicates a continuous tradition of cooking food. This is another in a series of discoveries relating to the high cognitive capabilities of the Acheulian hunter-gatherers who were active in the ancient Hula Valley region. These groups were deeply familiar with their environment and the various resources it offered them. Further, it shows they had extensive knowledge of the life cycles of different plant and animal species. Gaining the skill required to cook food marks a significant evolutionary advance, as it provided an additional means for making optimal use of available food resources. It is even possible that cooking was not limited to fish, but also included various types of animals and plants."

Prof. Hershkovitz and Dr. Zohar note that the transition from eating raw food to eating cooked food had dramatic implications for human development and behavior. Eating cooked food reduces the bodily energy required to break down and digest food, allowing other physical systems to develop. It also leads to changes in the structure of the human jaw and skull. This change freed humans from the daily, intensive work of searching for and digesting raw food, providing them free time in which to develop new social and behavioral systems. Some scientists view eating fish as a milestone in the quantum leap in human cognitive evolution, providing a central catalyst for the development of the human brain. They claim that eating fish is what made us human. Even today, it is widely known that the contents of fish flesh, such as omega-3 fatty acids, zinc, iodine and more, contribute greatly to brain development.

The research team believe that the location of freshwater areas, some of them in areas that have long since dried up and become arid deserts, determined the route of the migration of early man from Africa to the Levant and beyond. Not only did these habitats provide drinking water and attracted animals to the area but catching fish in shallow water is a relatively simple and safe task with a very high nutritional reward.

The team posits that exploiting fish in freshwater habitats was the first step on prehistoric humans' route out of Africa. Early man began to eat fish around 2 million years ago but cooking fish -- as found in this study -- represented a real revolution in the Acheulian diet and is an important foundation for understanding the relationship between man, the environment, climate, and migration when attempting to reconstruct the history of early humans.

It should be noted that evidence of the use of fire at the site -- the oldest such evidence in Eurasia -- was identified first by BIU's Prof. Nira Alperson-Afil. "The use of fire is a behavior that characterizes the entire continuum of settlement at the site," she explained. "This affected the spatial organization of the site and the activity conducted there, which revolved around fireplaces." Alperson-Afil's research of fire at the site was revolutionary for its time and showed that the use of fire began hundreds of thousands of years before previously thought.

HU's Goren-Inbar added that the archaeological site of GBY documents a continuum of repeated settlement by groups of hunter-gatherers on the shores of the ancient Hula Lake which lasting tens of thousands of years. "These groups made use of the rich array of resources provided by the ancient Hula Valley and left behind a long settlement continuum with over 20 settlement strata," Goren-Inbar explained. The excavations at the site have uncovered the material culture of these ancient hominins, including flint, basalt, and limestone tools, as well as their food sources, which were characterized by a rich diversity of plant species from the lake and its shores (including fruit, nuts, and seeds) and by many species of land mammals, both medium-sized and large.

Dr. Jens Najorka of the Natural History Museum in London explained: "In this study, we used geochemical methods to identify changes in the size of the tooth enamel crystals, as a result of exposure to different cooking temperatures. When they are burnt by fire, it is easy to identify the dramatic change in the size of the enamel crystals, but it is more difficult to identify the changes caused by cooking at temperatures between 200 and 500 degrees Celsius. The experiments I conducted with Dr. Zohar allowed us to identify the changes caused by cooking at low temperatures. We do not know exactly how the fish were cooked but given the lack of evidence of exposure to high temperatures, it is clear that they were not cooked directly in fire, and were not thrown into a fire as waste or as material for burning."

 

Plesiosaur fossils found in the Sahara suggest they weren't just marine animals

Plesiosaur illustration

Fossils of small plesiosaurs, long-necked marine reptiles from the age of dinosaurs, have been found in a 100-million year old river system that is now Morocco's Sahara Desert. This discovery suggests some species of plesiosaur, traditionally thought to be sea creatures, may have lived in freshwater.

Plesiosaurs, first found in 1823 by fossil hunter Mary Anning, were prehistoric reptiles with small heads, long necks, and four long flippers. They inspired reconstructions of the Loch Ness Monster, but unlike the monster of Lake Loch Ness, plesiosaurs were marine animals -- or were widely thought to be.

Now, scientists from the University of Bath and University of Portsmouth in the UK, and Université Hassan II in Morocco, have reported small plesiosaurs from a Cretaceous-aged river in Africa.

The fossils include bones and teeth from three-metre long adults and an arm bone from a 1.5 metre long baby. They hint that these creatures routinely lived and fed in freshwater, alongside frogs, crocodiles, turtles, fish, and the huge aquatic dinosaur Spinosaurus.

These fossils suggest the plesiosaurs were adapted to tolerate freshwater, possibly even spending their lives there, like today's river dolphins.

The new paper was headed by University of Bath Student Georgina Bunker, along with Nick Longrich from the University of Bath's Milner Centre for Evolution, David Martill and Roy Smith from the University of Portsmouth, and Samir Zouhri from the Universite Hassan II.

The fossils include vertebrae from the neck, back, and tail, shed teeth, and an arm bone from a young juvenile.

"It's scrappy stuff, but isolated bones actually tell us a lot about ancient ecosystems and animals in them. They're so much more common than skeletons, they give you more information to work with" said Dr. Nick Longrich, corresponding author on the paper.

"The bones and teeth were found scattered and in different localities, not as a skeleton. So each bone and each tooth is a different animal. We have over a dozen animals in this collection."

Whilst bones provide information on where animals died, the teeth are interesting because they were lost while the animal was alive -- so they show where the animals lived.

What's more, the teeth show heavy wear, like those fish-eating dinosaur Spinosaurus found in the same beds.

The scientists say that implies the plesiosaurs were eating the same food- chipping their teeth on the armored fish that lived in the river. This hints they spent a lot of time in the river, rather than being occasional visitors.

While marine animals like whales and dolphins wander up rivers, either to feed or because they're lost, the number of plesiosaur fossils in the river suggest that's unlikely.

A more likely possibility is that the plesiosaurs were able to tolerate fresh and salt water, like some whales, such as the beluga whale.

It's even possible that the plesiosaurs were permanent residents of the river, like modern river dolphins. The plesiosaurs' small size would have let them hunt in shallow rivers, and the fossils show an incredibly rich fish fauna.

Dr Longrich said: "We don't really know why the plesiosaurs are in freshwater.

"It's a bit controversial, but who's to say that because we paleontologists have always called them 'marine reptiles', they had to live in the sea? Lots of marine lineages invaded freshwater."

Freshwater dolphins evolved at least four times -- in the Ganges River, the Yangtze River, and twice in the Amazon. A species of freshwater seal inhabits Lake Baikal, in Siberia, so it's possible plesiosaurs adapted to freshwater as well.

The plesiosaurs belong to the family Leptocleididae- a family of small plesiosaurs often found in brackish or freshwater elsewhere in England, Africa, and Australia. And other plesiosaurs, including the long-necked elasmosaurs, turn up in brackish or fresh waters in North America and China.

Plesiosaurs were a diverse and adaptable group, and were around for more than 100 million years. Based on what they've found in Africa -- and what other scientists have found elsewhere -- the authors suggest they might have repeatedly invaded freshwater to different degrees.

"We don't really know, honestly. That's how paleontology works. People ask, how can paleontologists know anything for certain about the lives of animals that went extinct millions of years ago? The reality is, we can't always. All we can do is make educated guesses based on the information we have. We'll find more fossils. Maybe they'll confirm those guesses. Maybe not."

"It's been really interesting to see the direction this project has gone in," said lead author Georgina Bunker. The study initially began as an undergraduate project involving a single bone, but over time, more plesiosaur fossils started turning up, slowly providing a clearer picture of the animal.

The new discovery also expands the diversity of Morocco's Cretaceous. Said Dr. Samir Zouhri, "This is another sensational discovery that adds to the many discoveries we have made in the Kem Kem over the past fifteen years of work in this region of Morocco. Kem Kem was truly an incredible biodiversity hotspot in the Cretaceous."

"What amazes me" said coauthor Dave Martill, "is that the ancient Moroccan river contained so many carnivores all living alongside each other. This was no place to go for a swim."

But what does this all mean for the plausibility of something like a Loch Ness Monster? On one level, it's plausible. Plesiosaurs weren't confined to the seas, they did inhabit freshwater. But the fossil record also suggests that after almost a hundred and fifty million years, the last plesiosaurs finally died out at the same time as the dinosaurs, 66 million years ago.

Story Source: Science Daily