Egypt says archaeologists have discovered parts of a statue of one of its most famous pharaohs in the southern city of Aswan.
The head of a statue of one of the most famous pharaohs, Ramses II, that was discovered along with other parts of a statue in the Temple of Kom Ombo, in Aswan, 940 kilometres south of Cairo [Credit: Egyptian Ministry of Antiquities via AP]
The Antiquities Ministry said Tuesday the head and chest of the statue of Ramses II were found in the Temple of Kom Ombo during a project to protect the site from groundwater.
Egypt hopes the find, along with other recent discoveries, will help revive its tourism sector, which has been battered by years of unrest since the 2011 uprising.
Ramses II, also known as Ramses the Great, ruled Egypt from 1279 BC to 1213 BC. He is credited with expanding Egypt's reach as far as modern Syria to the east and Sudan to the south.
Geochronologists from the Centro Nacional de Investigación sobre la Evolución Humana (CENIEH) have led a study published in the journal Quaternary Geochronology about the chronology of the archaeological site of Gran Dolina, situated in the Sierra de Atapuerca (Burgos), whose results confirm a pulse of human dispersion in southern Europe around one million years ago..
TD4 Level at Gran Dolina site [Credit: CENIEH]
This is a paleomagnetic study of the lower stratigraphic levels of this archaeological site in Burgos, whose objective was to determine the possible presence of the Jaramillo subchron, a geological event of normal magnetic polarity about one million years ago, to improve the chronological framework for the lithic industry found at level TD4, and therefore for human presence in Atapuerca.
"Gran Dolina is one of the sites with the best-preserved sedimentary records of the Middle and Early Pleistocene in Europe, and therefore, knowing the chronology of the stratigraphic levels comprising it is an extremely important element in understanding the presence and development of human activity in the zone," explains Claudia Álvarez Posada, lead author of this paper.
Samples from the levels TD4 to TD6 were analyzed using paleomagnetism, a methodology which is increasingly used for establishing absolute datings given its great versatility and the fact that it has an extremely wide chronological register, because the magnetic field remains captured in sediments when they are formed. These days there is a known register covering a timeline of over 180 million years up to the present, so that as Álvarez affirms, "it's a very powerful tool for chronology."
This method, together with the data furnished by biostratigraphy and the recent dating studies using Electron Spin Resonance (ESR) made at the site, has allowed an age later than the Jaramillo Subchron to be definitively established for the level TD4, that is, less than one million years, consistent with with a pulse of human dispersal across southern Europe during the time interval known as the Lower Pleistocene transition.
Dual study
This paper forms part of a dual paleomagnetic study of Gran Dolina, encompassing levels TD1 to TD6, undertaken for better understanding of the ages of the different stratigraphic levels which comprise the fillings of the site.
The second paper, which has just been published in the journal Quaternary Science Reviews, focuses on the chronology of the lower sedimentary fillings, and corroborates the datings found for TD4.
Plumes of hot magma from the volcanic hotspot that formed Réunion Island in the Indian Ocean rise from an unusually primitive source deep beneath Earth's surface, according to new work in Nature from Carnegie's Bradley Peters, Richard Carlson, and Mary Horan along with James Day of the Scripps Institution of Oceanography.
A fieldwork photo from Réunion Island shows the flank of the Cirque de Cilaos, looking out towards the Indian Ocean [Credit: Bradley Peters]
Réunion marks the present-day location of the hotspot that 66 million years ago erupted the Deccan Traps flood basalts, which cover most of India and may have contributed to the extinction of the dinosaurs. Flood basalts and other hotspot lavas are thought to originate from different portions of Earth's deep interior than most volcanoes at Earth's surface and studying this material may help scientists understand our home planet's evolution.
The heat from Earth's formation process caused extensive melting of the planet, leading Earth to separate into two layers when the denser iron metal sank inward toward the center, creating the core and leaving the silicate-rich mantle floating above.
Over the subsequent 4.5 billion years of Earth's evolution, deep portions of the mantle would rise upwards, melt, and then separate once again by density, creating Earth's crust and changing the chemical composition of Earth's interior in the process. As crust sinks back into Earth's interior -- a phenomenon that's occurring today along the boundary of the Pacific Ocean -- the slow motion of Earth's mantle works to stir these materials, along with their distinct chemistry, back into the deep Earth.
Sunrise over the summit of Piton des Neiges, the extinct volcano on the Indian Ocean's Réunion Island [Credit: Bradley Peters]
But not all of the mantle is as well-blended as this process would indicate. Some older patches still exist -- like powdery pockets in a poorly mixed bowl of cake batter. Analysis of the chemical compositions of Réunion Island volcanic rocks indicate that their source material is different from other, better-mixed parts of the modern mantle.
Using new isotope data, the research team revealed that Réunion lavas originate from regions of the mantle that were isolated from the broader, well-blended mantle. These isolated pockets were formed within the first ten percent of Earth's history.
Isotopes are elements that have the same number of protons, but a different number of neutrons. Sometimes, the number of neutrons present in the nucleus make an isotope unstable; to gain stability, the isotope will release energetic particles in the process of radioactive decay. This process alters its number of protons and neutrons and transforms it into a different element. This new study harnesses this process to provide a fingerprint for the age and history of distinct mantle pockets.
Looking into down into a volcanic crater of Piton de la Fournaise on Réunion Island with dormant volcanic cones in the background [Credit: Bradley Peters]
Samarium-146 is one such unstable, or radioactive, isotope with a half-life of only 103 million years. It decays to the isotope neodymium-142. Although samarium-146 was present when Earth formed, it became extinct very early in Earth's infancy, meaning neodymium-142 provides a good record of Earth's earliest history, but no record of Earth from the period after all the samarium-146 transformed into neodymium-142. Differences in the abundances of neodymium-142 in comparison to other isotopes of neodymium could only have been generated by changes in the chemical composition of the mantle that occurred in the first 500 million years of Earth's 4.5 billion-year history.
The ratio of neodymium-142 to neodymium-144 in Réunion volcanic rocks, together with the results of lab-based mimicry and modeling studies, indicate that despite billions of years of mantle mixing, Réunion plume magma likely originates from a preserved pocket of the mantle that experienced a compositional change caused by large-scale melting of Earth's earliest mantle.
The team's findings could also help explain the origin of dense regions right at the boundary of the core and mantle called large low shear velocity provinces (LLSVPs) and ultralow velocity zones (ULVZs), reflecting the unusually slow speed of seismic waves as they travel through these regions of the deep mantle. Such regions may be relics of early melting events.
"The mantle differentiation event preserved in these hotspot plumes can both teach us about early Earth geochemical processes and explain the mysterious seismic signatures created by these dense deep-mantle zones," said lead author Peters. Source: Carnegie Institution for Science [February 28, 2018]
A scientist with the Canadian Museum of Nature has answered a long-standing mystery about why fossils of ankylosaurs -- the "armoured tanks" of the dinosaur world -- are mainly found belly-side up. In doing so, he has ruled out three other competing theories involving clumsiness, predation, and the effects of bloating as seen in armadillo roadkills.
Illustration of Euoplocephalus, an ankylosaur. Ankylosaurids are sometimes called the 'tanks of the Cretaceous' given their squat bodies and armored hides [Credit: Brett Booth Brett Booth]
Palaeontologist Dr. Jordan Mallon says the evidence points to a phenomenon called "bloat-and-float," whereby the bloating carcasses of ankylosaurs would end up in a river, flip belly-side up due to the weight of their heavy armour, and then float downstream. The remains would wash ashore, where decomposition and then fossilization would seal the dinosaur remains in their upside-down death pose.
"Textbooks have touted that ankylosaur fossils are usually found upside down, but no one has gone back and checked the records to make sure that's the case," explains Mallon. The observations date from the 1930s. Indeed, the fossils of two star ankylosaurs described in 2017, Borealopelta from Alberta and Zuul from Montana, were found upside down.
Mallon examined 32 ankylosaur fossils from Alberta (of which 26 were found belly up), photos of specimens, field notes, and other signs such as erosion of the exposed surface, sun bleaching, and the presence of lichens.
The results are published in the online journal Palaeogeography, Palaeoclimatology, Palaeoecology. Collaborators included armadillo experts Drs. Colleen McDonough and Jim Loughry of Valdosta State University in Georgia, and Dr. Don Henderson, with Drumheller Alberta's Royal Tyrrell Museum of Palaeontology.
Mallon ruled out three other theories before settling on "bloat-and-float" to explain the preponderance of the belly-up remains.
"One idea was that ankylosaurs were simply clumsy, tripping over themselves or rolling down hills and ending up dying that way," he says. But since ankylosaurs existed for about 100 million years, clumsy habits would not fit with their apparent evolutionary success.
Another theory was that ankylosaurs were prey for carnivores, such as hungry tyrannosaurids, which would flip the armoured dinosaurs onto their backs to get at the soft underbelly. "If this was true, we would expect to see signs of bite marks, especially on upside-down ones, but we saw marks on only one specimen," explains Mallon. "Since they were armoured, it makes sense that ankylosaurs were not regularly preyed upon, and the fossil evidence in museum collections supports this."
The third idea, proposed in the 1980s, is an analogy to what happens with some armadillo roadkills -- as the carcass rots and bloats, gas accumulates, and the limbs would splay out, eventually rolling the animal onto its back.
The challenge was to test this hypothesis. Enter McDonough and Loughry who are experts on modern armadillos, which also have an armoured shell. Over the summer of 2016, they studied 174 examples of dead armadillo. "Sure enough, the data show that they do not occur more often on their backs," says Mallon. The pair even examined dead armadillos placed in plexiglass cases in their backyard to keep away scavengers. Regardless of the positioning of the carcasses, bloating did not cause them to roll over onto their backs.
That left the "bloat-and-float" hypothesis as the most likely explanation for the presence of upside-down fossils. To study this, Mallon turned to computer simulations developed by Dr. Don Henderson, who specializes in the floating behaviour of animals in water.
Ankylosaur fossils in North America are found in river channel deposits, and in the Late Cretaceous Period these animals would have been living along a coastline of what is known as the Western Interior Seaway.
"We designed these models of ankylosaurs, both clubless and clubbed, and looked at their floating behavior," explains Mallon. The computer modelling showed that the animals would tend to flip upside down quite easily in water. Nodosaurids, which are ankylosaurs with no tail clubs, would flip most easily at the slightest tilt; the ankyosaurids (with clubbed tails), were more stable but could still be flipped.
"So 'bloat-and-float'" fits with their known environment, and this research helps inform about the transport behavior of dead dinosaurs, which is important to know when studying fossil ecosystems. Ultimately, this is a classic case study of the scientific method: examining alternative hypotheses, finding ways to test them, and ruling them out one-by-one. What you are left with at the end is the most likely explanation."
Fossilized bones of two new species of tiny, flightless extinct birds have been discovered by Australasian scientists in 19 to 16-million-year-old sediments of an ancient lake on the South Island of New Zealand.
A tiny extinct rail (30-40g) is overshadowed by a regular duck [Credit: Gavin Mouldey]
The two miniscule species—one barely larger than a sparrow—were members of the rail family, a group of birds common today in wetlands that includes swamphens, moorhens, coots and crakes. Their remains were unearthed near the town of St Bathans in Central Otago.
Many rail species can fly well and have dispersed to far-flung oceanic islands. However, flightlessness has evolved more times in this group of birds that in any other, especially on predator-free islands. The world's largest rails evolved in New Zealand, notably the flightless takahe and weka.
The study, led by scientists from Flinders University with colleagues from UNSW, Canterbury Museum and the Museum of New Zealand, is published in the Journal of Systematic Palaeontology.
Team member UNSW Professor Mike Archer, says: "This new discovery emphasizes the fact that New Zealand has long been one of the world's most extraordinary engines driving bird evolution.
"Charting how lineages like these rails have changed through time on an island that has been geographically isolated for more than 80 million years will test basic presumptions made about bird evolution in general," says Professor Archer of the of the PANGEA Research Centre in the School of Biological, Earth and Environmental Sciences.
Nineteen to 16 million years ago, a 5600 square kilometre megalake dominated the landscape of New Zealand's South Island. It was surrounded by a subtropical rainforest and plants typical of Australia and long lost from New Zealand, such as eucalypts, casuarinas, palms and cycads, were common there.
"Flightlessness in birds is often associated with an increase in size," says Ellen Mather, study lead author and Ph.D. student at Flinders University. "The weka, which is in the same family as our fossil birds and lives in New Zealand today, is about the size of a chicken. The Banded Rail, their closest flying relative, is about half that size."
The most common of the new fossil rails has been named Priscaweka parvales, meaning ancient weka with small wings. It was a mere one twentieth of the weight of a weka and was similar in size to the recently extinct Chatham rail Cabalus modestus.
Small flightless birds only exist in the absence of terrestrial mammalian predators, and New Zealand has long been recognised as the iconic example of a country with an avifauna which evolved in the absence of such predators.
When humans discovered New Zealand, the main islands had many flightless birds including giants within the nine species of moa, several kiwi, two huge geese, two adzebills, even some tiny wrens, and at least five flightless rails.
Team member, Dr. Paul Scofield, a Senior Curator at the Natural History at Canterbury Museum, says: "The new St Bathans' rails join a host of other fossil birds recovered from these deposits that show New Zealand has long been a land of birds. The discovery of these two miniscule flightless rails raises the question of 'Where did they come from?'"
The researchers suggest they had ancestors in Australia which flew across the 1500 km ocean to New Zealand in previous millennia. However, the new species are unlike any rail known elsewhere, so their exact origin or closest relatives remain a mystery.
Other than hints of large flightless moa ancestors, these rails are the first flightless birds to be described from this fauna. This is unexpected as the St Bathans Fauna contains small terrestrial mammals, which normally preclude evolution of small flightless species. The tiny flightless rails therefore strongly suggest that the mysterious mammals were not predators of small birds. Flightless birds have been a feature of the New Zealand avifauna for millions of years, much longer than previously thought. They are probably the oldest flightless rails known globally.
"The ongoing research into the fossil birds of New Zealand builds on that begun over 150 years ago. It continues to throw up revelations into the timing and origins of major groups of birds that characterize modern avifaunas" says Associate Professor Trevor Worthy of Flinders University.
Rainforest loss is fuelling a tsunami of tropical species extinctions. However, not all is doom and gloom. A new study, conducted in the Brazilian Amazon, suggests that ecological cataclysms prompted by the fragmentation of the forest can be reverted by the regeneration of secondary forests, offering a beacon of hope for tropical forest biodiversity across the world.
Credit: Mark Moffett/ Minden Pictures/National Geographic Stock
The international team of researchers found that species strongly associated with primary forest were heavily depleted after 15 years of man-made disruption including the burning and clearing of forest stands,
However, 30 years down the line, and with the regeneration of secondary regrowth, many of the species that had abandoned the area had made a comeback.
"If you compare the time periods, it is apparent that taking a long-term view is paramount to uncovering the complexity of biodiversity in human-modified landscapes," said senior researcher Dr. Christoph Meyer, lecturer in global ecology and conservation at the University of Salford.
The study, published in Nature: Scientific Reports, measured the impacts of forest break-up of 50 species of bat (approx. 6,000 animals).
Bats comprise roughly one fifth of all mammal species and display wide variation in foraging behaviour and habitat use, making them an excellent model group for the research.
"The responses exhibited by bats offer important insights into the responses of other taxonomic groups." says Ricardo Rocha, lead author of the study from the University of Lisbon.
"The recovery that we have documented mirrors the patterns observed for beetle and bird communities within the Amazon.
"These parallel trends reinforce the idea that the benefits of forest regeneration are widespread, and suggest that habitat restoration can ameliorate some of the harm inflicted by humans on tropical wildlife", he adds.
The results of the current study contrast with the catastrophic faunal declines observed during a similar time window in rodent communities in the 'forest islands' of the Chiew Larn reservoir in Thailand.
"The recovery observed at the Amazon was mostly due to the recolonization of previously deforested areas and forest fragments by old-growth specialist bats. This recolonization is likely attributable to an increased diversity and abundance of food resources in areas now occupied by secondary forest, fulfilling the energetic requirements of a larger set of species", explains Rocha.
However, the short-term nature of most studies has substantially impaired the capacity of researchers to properly capture the intricate time-related complexities associated with the effects of forest fragmentation on wildlife.
Long ago, about 400,000 years after the beginning of the universe (the Big Bang), the universe was dark. There were no stars or galaxies, and the universe was filled primarily with neutral hydrogen gas.
This artist's rendering shows the universe's first, massive, blue stars embedded in gaseous filaments, with the cosmic microwave background just visible at the edges. Using radio observations of the distant universe, NSF-funded researchers Judd Bowman of Arizona State University, Alan Rogers of MIT and their colleagues discovered the influence of such early stars on primordial gas. Although they can't directly see the light from the massive stars, Bowman's team was able to infer their presence from dimming of the cosmic microwave background (CMB), a result of the gaseous filaments absorbing the stars' UV light. The CMB is dimmer than expected, indicating that the filaments may have been colder than expected, possibly from interactions with dark matter [Credit: N.R.Fuller, National Science Foundation]
Then, for the next 50-100 million years, gravity slowly pulled the densest regions of gas together until ultimately the gas collapsed in some places to form the first stars.
What were those first stars like and when did they form? How did they affect the rest of the universe? These are questions astronomers and astrophysicists have long pondered.
Now, after 12 years of experimental effort, a team of scientists, led by ASU School of Earth and Space Exploration astronomer Judd Bowman, has detected the fingerprints of the earliest stars in the universe. Using radio signals, the detection provides the first evidence for the oldest ancestors in our cosmic family tree, born by a mere 180 million years after the universe began.
"There was a great technical challenge to making this detection, as sources of noise can be a thousand times brighter than the signal -- it's like being in the middle of a hurricane and trying to hear the flap of a hummingbird's wing." says Peter Kurczynski, the National Science Foundation program officer who supported this study. "These researchers with a small radio antenna in the desert have seen farther than the most powerful space telescopes, opening a new window on the early universe."
Radio Astronomy
To find these fingerprints, Bowman's team used a ground-based instrument called a radio spectrometer, located at the Australia's national science agency (CSIRO) Murchison Radio-astronomy Observatory (MRO) in Western Australia. Through their Experiment to Detect the Global EoR Signature (EDGES), the team measured the average radio spectrum of all the astronomical signals received across most of the southern-hemisphere sky and looked for small changes in power as a function of wavelength (or frequency).
In each instrument, radio waves are collected by an antenna consisting of two rectangular metal panels mounted horizontally on fiberglass legs above a metal mesh. The EDGES detection required the radio quietness at the Murchison Radio-astronomy Observatory, as Australian national legislation limits the use of radio transmitters near the site. This discovery sets the stage for follow-up observations with other powerful low-frequency facilities, including HERA and the forthcoming SKA-low [Credit: CSIRO Australia]
As radio waves enter the ground-based antenna, they are amplified by a receiver, and then digitized and recorded by computer, similar to how FM radio receivers and TV receivers work. The difference is that the instrument is very precisely calibrated and designed to perform as uniformly as possible across many radio wavelengths.
The signals detected by the radio spectrometer in this study came from primordial hydrogen gas that filled the young universe and existed between all the stars and galaxies. These signals hold a wealth of information that opens a new window on how early stars -- and later, black holes, and galaxies -- formed and evolved.
"It is unlikely that we'll be able to see any earlier into the history of stars in our lifetimes," says Bowman. "This project shows that a promising new technique can work and has paved the way for decades of new astrophysical discoveries."
This detection highlights the exceptional radio quietness of the MRO, particularly as the feature found by EDGES overlaps the frequency range used by FM radio stations. Australian national legislation limits the use of radio transmitters within 161.5 miles (260 km) of the site, substantially reducing interference which could otherwise drown out sensitive astronomy observations.
The results of this study have been recently published in Nature by Bowman, with co-authors Alan Rogers of the Massachusetts Institute of Technology's Haystack Observatory, Raul Monsalve of the University of Colorado, and Thomas Mozdzen and Nivedita Mahesh also of ASU's School of Earth and Space Exploration.
Unexpected results
The results of this experiment confirm the general theoretical expectations of when the first stars formed and the most basic properties of early stars.
A timeline of the universe, updated to show when the first stars emerged. This updated timeline of the universe reflects the recent discovery that the first stars emerged by 180 million years after the Big Bang. The research behind this timeline was conducted by Judd Bowman of Arizona State University and his colleagues, with funding from the National Science Foundation [Credit: N.R.Fuller, National Science Foundation]
"What's happening in this period," says co-author Rogers of MIT's Haystack Observatory, "is that some of the radiation from the very first stars is starting to allow hydrogen to be seen. It's causing hydrogen to start absorbing the background radiation, so you start seeing it in silhouette, at particular radio frequencies. This is the first real signal that stars are starting to form, and starting to affect the medium around them."
The team originally tuned their instrument to look later in cosmic time, but in 2015 decided to extend their search. "As soon as we switched our system to this lower range, we started seeing things that we felt might be a real signature," Rogers says. "We see this dip most strongly at about 78 megahertz, and that frequency corresponds to roughly 180 million years after the Big Bang," Rogers says. "In terms of a direct detection of a signal from the hydrogen gas itself, this has got to be the earliest."
The study also revealed that gas in the universe was probably much colder than expected (less than half the expected temperature). This suggests that either astrophysicists' theoretical efforts have overlooked something significant or that this may be the first evidence of non-standard physics: Specifically, that baryons (normal matter) may have interacted with dark matter and slowly lost energy to dark matter in the early universe, a concept that was originally proposed by Rennan Barkana of Tel Aviv University.
"If Barkana's idea is confirmed," says Bowman, "then we've learned something new and fundamental about the mysterious dark matter that makes up 85 percent of the matter in the universe, providing the first glimpse of physics beyond the standard model."
The next steps in this line of research are for another instrument to confirm this team's detection and to keep improving the performance of the instruments, so that more can be learned about the properties of early stars. "We worked very hard over the last two years to validate the detection," says Bowman, "but having another group confirm it independently is a critical part of the scientific process."
Bowman would also like to see an acceleration of efforts to bring on new radio telescopes like the Hydrogen Epoch of Reionization Array (HERA) and the Owens Valley Long Wavelength Array (OVRO-LWA).
"Now that we know this signal exists," says Bowman, "we need to rapidly bring online new radio telescopes that will be able to mine the signal much more deeply."
The antennas and portions of the receiver used in this experiment were designed and constructed by Rogers and the MIT Haystack Observatory team. The ASU team and Monsalve added the automated antenna reflection measurement system to the receiver, outfitted the control hut with the electronics, constructed the ground plane and conducted the field work for the project. The current version of EDGES is the result of years of design iteration and ongoing detailed technical refinement of the calibration instrumentation to reach the levels of precision necessary for successfully achieving this difficult measurement.
