A world map that shows where similary platinum spikes have been discovered in the world. The latest discovery is at the Wonderkrater site in Limpopo Province, South Africa. Credit: Francis Thackeray/Wits University
A team of scientists from South Africa has discovered evidence partially supporting a hypothesis that Earth was struck by a meteorite or asteroid 12 800 years ago, leading to global consequences including climate change, and contributing to the extinction of many species of large animals at the time of an episode called the Younger Dryas.
The team, led by Professor Francis Thackeray of the Evolutionary Studies Institute at the University of the Witwatersrand in Johannesburg, South Africa, discovered evidence of a remarkable “platinum spike” at a site called Wonderkrater in the Limpopo Province, north of Pretoria in South Africa. Working with researcher Philip Pieterse from the University of Johannesburg and Professor Louis Scott of the University of the Free State, Thackeray discovered this evidence from a core drilled in a peat deposit, notably in a sample about 12 800 years old. This research was published in Palaeontologia Africana.
Noting that meteorites are rich in platinum, Thackeray said “Our finding at least partially supports the highly controversial Younger Dryas Impact Hypothesis (YDIH). We seriously need to explore the view that an asteroid impact somewhere on earth may have caused climate change on a global scale, and contributed to some extent to the process of extinctions of large animals at the end of the Pleistocene, after the last ice age.”
Many mammals became extinct in North America, South America and Europe at the time of the Younger Dryas. In South Africa a few extraordinary large animal species became extinct, not necessarily at exactly 12 800 years ago, but close to that period. These megafauna include a giant African buffalo, a large zebra, and a very big wildebeest.
Human populations may also have been indirectly affected at the time in question. In North America there is a dramatic termination of the stone tool technology of Clovis people. Remarkably, archaeologists in South Africa have detected an almost simultaneous termination of the Robberg stone artifact industry associated with people in some parts of the country, including the area around Boomplaas near the Cango Caves in the southern Cape, close to the town of Oudshoorn.
“Without necessarily arguing for a single causal factor on a global scale, we cautiously hint at the possibility that these technological changes, in North America and on the African subcontinent at about the same time, might have been associated indirectly with an asteroid impact with major global consequences,” says Thackeray. “We cannot be certain, but a cosmic impact could have affected humans as a result of local changes in environment and the availability of food resources, associated with sudden climate change.”
At Wonderkrater, the team has evidence from pollen to show that about 12 800 years ago there was temporary cooling, associated with the “Younger Dryas” drop in temperature that is well documented in the northern hemisphere, and now also in South Africa. According to some scientists, this cooling in widespread areas could at least potentially have been associated with the global dispersal of platinum-rich atmospheric dust.
A large crater 31 kilometers in diameter has been discovered in northern Greenland beneath the Hiawatha Glacier. “There is some evidence to support the view that it might possibly have been the very place where a large meteorite struck the planet earth 12 800 years ago,” says Thackeray. “If this was indeed the case, there must have been global consequences.”
Thackeray’s team believes their discovery of a platinum spike at about 12 800 years ago at Wonderkrater is just part of the strengthening view that an asteroid or cometary impact might have occurred at that time.
This is the first evidence in Africa for a platinum spike preceding climate change. Younger Dryas spikes in platinum have also been found in Greenland, Eurasia, North America, Mexico and recently also at Pilauco in Chile. Wonderkrater is the 30th site in the world for such evidence.
“Our evidence is entirely consistent with the Younger Dryas Impact Hypothesis” says Thackeray.
The discovery in South Africa is expected to be integrated with those made in other parts of the world, recognizing that the source of the platinum at Wonderkrater could hypothetically be cosmic dust that was dispersed in the atmosphere after a meteorite impact in Greenland.
The probability of a large asteroid striking Earth in the future may seem to be low, but there are thousands of large rocks distributed primarily between Jupiter and Mars. One in particular, classified as Apophis 99942, is referred to as a “Potentially Hazardous Asteroid.” It is 340 meters wide and will come exceptionally close to the Earth in 10 years’ time.
“The closest encounter will take place precisely on Friday April 13, 2029,” says Thackeray. “The probability of the Apophis 99942 asteroid hitting us then is only one in 100 000, but the probability of an impact may be even higher at some time in the future, as it comes close to Earth every 10 years.”
Reference:
The Younger Dryas interval at Wonderkrater (South Africa) in the context of a platinum anomaly hdl.handle.net/10539/28129
A river flows between mountains at Yellowstone National Park in Wyoming. New research tests a 30-year-old theory on the relationship between erosion and mountain height. Photo credit: Seth Cottle/Unsplash
Over millions of years, Earth’s summits and valleys have moved and shifted, resulting in the dramatic landscapes of peaks and shadows we know today. Mountains often form when pressure under Earth’s surface pushes upward, yet many factors impact their ultimate height, including the erosion of the areas between mountains, known as channels.
Scientists have long assumed that as land is pushed faster upward to form a mountain, its height increases in a continuous and predictable way. But new research shows that these predictions may stop working for the steepest mountains and therefore limit their height — and this may hold true for ranges on the entire planet.
“People have argued for a long time that as channels get steeper and steeper, the erosion rate keeps increasing,” said George Hilley, a professor of geological sciences at Stanford University’s School of Earth, Energy & Environmental Sciences (Stanford Earth) and lead author of a study published in Nature Geoscience Sept. 16. “We find that the theory works really well until a certain point and then it breaks down empirically — it seems as though something else kicks in that we don’t completely understand.”
The researchers analyzed samples from a broad range of mountain landscapes across the tropics, including Venezuela, Brazil, Guatemala, Costa Rica and Taiwan, controlling for rock type and climate conditions to assess parallel comparisons. They found that after mountains reach a certain elevation, channels between mountains suddenly become extremely sensitive to subtle changes in their inclines, thereby limiting the height of the mountains above. They added data from hundreds of mountain ranges worldwide and found they followed a similar pattern: the height, or relief, of the landscape is capped after crossing a threshold driven by channel steepness.
“Areas of land above channels are likely being controlled by how quickly a river can cut down — this is the framework by which we understand how the height of mountains varies as a function of climate and the collision of continents,” Hilley said. “The anomaly we observed is kind of a mystery and is not necessarily what conventional theory might predict.”
Research impacts
By bringing evidence of this mysterious factor influencing mountain height, the research could impact other work, such as studies on the relationship between mountain erosion rates and climate — important elements for understanding ancient climate and forecasting future patterns.
“Our work adds an interesting depth to some of these studies, because the way in which Earth’s topography changes as climates become more or less erosive may also change as the threshold is approached,” Hilley said.
The work also has implications for the geophysical links of mountain formation, which scientists are interested in exploring to understand the hidden activity of tectonic movements below our feet.
“People like me have always hoped that you could actually use the topography in order to say something about how quickly faults might be slipping,” Hilley said. “What our results say is that you can still do that in landscapes that are moderately steep, but it might become increasingly difficult as landscapes become steeper.”
Global patterns
The scientists took a fundamentally different approach to the research by searching the globe for conditions that reveal changes in mountain height rather than focusing on just one location. That search led them to focus on ranges in the tropics, but the conclusions were consistent across all regions of the globe and may also be applied to understand ancient topography.
“The Himalayas are being uplifted pretty rapidly and they expose pretty hard rocks, and indeed, when you measure them out, they are pretty close to this threshold,” he said. “You might be able to take this threshold with just the modern configuration of the landscape and actually place some upper bound on what the topography of the ancient Himalayas looked like.”
Hilley said the results of the study were surprising, as well as the fact that they remained consistent when compared with global data.
“In retrospect it makes sense when you look at it from the overall context of what our planet actually looks like,” Hilley said. “It really speaks to the fact that there might be lots of fertile ground to explore why this might happen. It also points to the fact that there might be something about the way in which rivers incise that we just don’t understand yet.”
Reference:
George E. Hilley, Stephen Porder, Felipe Aron, Curtis W. Baden, Samuel A. Johnstone, Frances Liu, Robert Sare, Aaron Steelquist, Holly H. Young. Earth’s topographic relief potentially limited by an upper bound on channel steepness. Nature Geoscience, 2019; DOI: 10.1038/s41561-019-0442-3
Subduction forced the younger oceanic crust down beneath the supercontinent Pangaea millions of years ago. Credit: University of Melbourne
Our planet formed around 4.54 billion years ago but few hints of this ancient world remain—just a small outcrop of rocks in northwestern Canada dating back 4.03 billion years and tiny crystals of the mineral zircon from western Australia that are about 4.3 billion years old.
The vast majority of the thin crust that we live on is considerably younger; this lack of preserved older material is a consequence of our dynamic planet.
The constant jostling of tectonic plates forms and destroys rocks, while the action of the hydrological cycle—rain, rivers, glaciers, oceans—tends to erode and redistribute their constituents.
For many decades, however, scientists have hypothesized that there are areas deep in the Earth’s interior that contain material untouched since the planet was formed.
These domains of primordial material are leftovers from the ancient event that saw the separation of our planet’s core from the silicate component which makes up most of the Earth’s crust and mantle.
Now, new University of Melbourne research is shedding some light on this puzzle using kimberlites—an igneous rock.
These unusual magmas are the primary source of one of our most treasured commodities—diamonds. They are the only volcanic deposits we know to have come from Earth’s deep mantle and they provide a fascinating glimpse into our planet’s formation.
Despite our best efforts, hypotheses about what lies deep in the Earth’s interior have remained largely untested.
We can create images of our planet’s interior using geophysical techniques involving seismic wave transmission, but it is a much harder task to determine the composition of the deep Earth.
Samples are rarely presented to us for analysis, and we do not have the technology to drill into the Earth’s mantle to find this material at its source.
The deepest hole ever drilled, the Kola Superdeep Borehole in northwest Russia, reaches just over 12 kilometers in depth.
Although that may sound deep, it’s barely one third of the way through the crust in that region. In fact, we would need to dig more than 500 kilometers further into the underlying mantle to have any chance of finding primordial material.
Many of our ideas about the composition of the Earth’s interior actually come from meteorites.
We believe they derive from catastrophic collisions that released material from deep within early solar system planets that were formed in a similar way to the Earth.
However, there are rare eruptive events that bring to the surface material from deep in the Earth, such as kimberlites.
Kimberlite eruptions have never been witnessed, because most kimberlites were formed millions to billions of years ago.
But we know from their textures and volatile-rich nature that these eruptions must have been extremely violent, traveling through the Earth’s mantle at extreme speed and sampling their surroundings as they went.
A small percentage of diamonds carry tiny inclusions of other minerals which are only stable at great pressures, providing clear evidence of their formation happening at depths of up to 800 kilometers.
In our study with University of Melbourne researchers Professor David Phillips and Drs Andrea Giuliani and Roland Maas, Professor Graham Pearson from the University of Alberta, and Dr. Geoff Nowell from Durham University, we measured the composition of kimberlites that erupted over a 2.5 billion year period of Earth history; collecting data and samples from thirteen kimberlite fields globally, spanning every continent except Antarctica.
Using sensitive radioisotope tracers, we can map the evolution of their mantle sources through time.
Our results show that, prior to around 200 million years ago, all kimberlites that erupted on Earth were likely sourced from a single primordial reservoir, formed soon after Earth’s core formed.
Then, around 200 million years ago, this reservoir appears to have been disrupted.
This was possibly due to a vast subduction zone established along the margins of the supercontinent Pangaea—the single continent that predated the seven continents that we now have.
Here, collision between tectonic plates forced the younger oceanic crust down beneath the supercontinent and back into the Earth’s deeper mantle. This material may have resulted in the contamination of the primordial reservoir.
These observations provide our best evidence yet for the existence of an early primordial reservoir within the Earth’s mantle—a subject of intense speculation for the last four decades.
And this major event around 200 million years ago may well have represented a significant turning point in the Earth’s geochemical evolution.
Machu Pichu. Detailed mapping indicates the World Heritage Site’s location and layout were dictated by the underlying geological faults. Photo taken 5 Nov. 2010; credit: Rualdo Menegat.
The ancient Incan sanctuary of Machu Picchu is considered one of humanity’s greatest architectural achievements. Built in a remote Andean setting atop a narrow ridge high above a precipitous river canyon, the site is renowned for its perfect integration with the spectacular landscape. But the sanctuary’s location has long puzzled scientists: Why did the Incas build their masterpiece in such an inaccessible place? Research suggests the answer may be related to the geological faults that lie beneath the site.
On Monday, 23 Sept. 2019, at the GSA Annual meeting in Phoenix, Rualdo Menegat, a geologist at Brazil’s Federal University of Rio Grande do Sul, will present the results of a detailed geoarchaeological analysis that suggests the Incas intentionally built Machu Picchu — as well as some of their cities — in locations where tectonic faults meet. “Machu Pichu’s location is not a coincidence,” says Menegat. “It would be impossible to build such a site in the high mountains if the substrate was not fractured.”
Using a combination of satellite imagery and field measurements, Menegat mapped a dense web of intersecting fractures and faults beneath the UNESCO World Heritage Site. His analysis indicates these features vary widely in scale, from tiny fractures visible in individual stones to major, 175-kilometer-long lineaments that control the orientation of some of the region’s river valleys.
Menegat found that these faults and fractures occur in several sets, some of which correspond to the major fault zones responsible for uplifting the Central Andes Mountains during the past eight million years. Because some of these faults are oriented northeast-southwest and others trend northwest-southeast, they collectively create an “X” shape where they intersect beneath Machu Picchu.
Menegat’s mapping suggests that the sanctuary’s urban sectors and the surrounding agricultural fields, as well as individual buildings and stairs, are all oriented along the trends of these major faults. “The layout clearly reflects the fracture matrix underlying the site,” says Menegat. Other ancient Incan cities, including Ollantaytambo, Pisac, and Cusco, are also located at the intersection of faults, says Menegat. “Each is precisely the expression of the main directions of the site’s geological faults.”
Menegat’s results indicate the underlying fault-and-fracture network is as integral to Machu Picchu’s construction as its legendary stonework. This mortar-free masonry features stones so perfectly fitted together that it’s impossible to slide a credit card between them. As master stoneworkers, the Incas took advantage of the abundant building materials in the fault zone, says Menegat. “The intense fracturing there predisposed the rocks to breaking along these same planes of weakness, which greatly reduced the energy needed to carve them.”
In addition to helping shape individual stones, the fault network at Machu Picchu likely offered the Incas other advantages, according to Menegat. Chief among these was a ready source of water. “The area’s tectonic faults channeled meltwater and rainwater straight to the site,” he says. Construction of the sanctuary in such a high perch also had the benefit of isolating the site from avalanches and landslides, all-too-common hazards in this alpine environment, Menegat explains.
The faults and fractures underlying Machu Picchu also helped drain the site during the intense rainstorms prevalent in the region. “About two-thirds of the effort to build the sanctuary involved constructing subsurface drainages,” says Menegat. “The preexisting fractures aided this process and help account for its remarkable preservation,” he says. “Machu Picchu clearly shows us that the Incan civilization was an empire of fractured rocks.”
A life reconstruction of the feathered dinosaur Anchiornis huxleyi based on fossil evidence of its color and patterning. This evidence included inferences about melanin pigments. Credit: HKU MOOC / Julius T Csotonyi / Michael Pittman.
Dr Michael Pittman of the Vertebrate Palaeontology Laboratory, Department of Earth Sciences, The University of Hong Kong led an international study with his PhD student Mr Arindam Roy that evaluates fossil colour reconstruction methods to propose a new study framework that improves and expands current practice. The paper was recently published in the journal Biological Reviews.
“People are fascinated by the colour and pattern of dinosaurs and other extinct animals because these aspects can tell you so much about an animal. Just think of a zebra and a peacock. We evaluated everything we know about fossil and modern animal colour and used that knowledge to propose a framework to improve how we reconstruct fossil colour in the future.” said Dr Pittman.
Colour and patterns are critical to understanding the life, ecology, physiology and behaviour of animals. These colours are produced when light interacts with pigments and the structure of animal tissue. Common naturally-occurring animal pigments include melanin, carotenoids, porphyrins pterins, flavins and psittacofulvins which produce colours ranging from black and grey to yellow, orange and green.
Feathered dinosaur fossils instrumental to understanding the origin of birds were the first animal fossils to yield evidence of melanin, the colour pigment we also have in our eyes and hair. In the last ten years, colour patterns have been reconstructed in over 30 fossil animals including birds, non-avialan dinosaurs and mammals, providing a unique opportunity to test ecological and behavioral hypotheses that were previously out of reach. Unfortunately, our knowledge of other pigments is scarce in the fossil record as these non-melanin pigments are more difficult to fossilise. This incomplete knowledge and the lack of a standard study approach have been prevailing challenges to the reconstruction of colour in fossil animals.
Co-author Dr Evan Saitta of the Field Museum of Natural History, Chicago, USA said, “We are in the golden age of multidisciplinary techniques in palaeontology. This is the first comprehensive study that not only critically evaluates the currently available methods, but also provides a reliable and repeatable framework that covers all vertebrate pigment systems not just melanin alone.”
The new palaeocolour reconstruction framework proposed by Dr Michael Pittman, Mr Arindam Roy and their international team comprises four main steps: (1) Map the known or suspected extent of preserved colour and patterns in the specimen; (2) Search for pigment-bearing microstructures using electron microscopy e.g. microstructure shape can be used to identify melanin-based colours like black, grey and brown); (3) If melanin-based colours are not detected, use high-end chemical analysis techniques to detect biomarkers of other pigments (4) Use reconstructed colours and patterns to test fundamental hypotheses related to animal physiology, ecology and behaviour. The new framework overcomes past challenges by incorporating the chemical signatures of different pigments, large and small-scale anatomical details visible in fossils as well as the potential for different pigments to fossilise. This framework provides background context for the evolution of colour-producing mechanisms and is expected to encourage future efforts to reconstruct colour in more fossil animals including non-dinosaur reptiles and mammals.
Mr Roy, the study’s first author and a Hong Kong PhD Fellow said, “I am really excited by the course we have charted in this review study as I will be tackling many of the key issues we identified during my PhD studies at HKU.”
Reference:
Arindam Roy, Michael Pittman, Evan T. Saitta, Thomas G. Kaye, Xing Xu. Recent advances in amniote palaeocolour reconstruction and a framework for future research. Biological Reviews, 2019; DOI: 10.1111/brv.12552
Artist’s reconstruction of two rauisuchians fighting over a desiccated corpse of a mammal-relative in the Triassic of southern Africa. In the background, dinosaurs and mammal-like reptiles form other parts of the ecosystem. Credit: Viktor Radermacher, owns copyright
“These ancient fossils provide us with evidence of how at least two predator species hunted these vegetarian dinosaurs 210 million-years-ago. It is amazing to follow the clues left behind in fossilised teeth, jaws, limbs and other fossils to help us tell the ancient story of life in southern Africa,” says Tolchard.
The fossils studied by Tolchard include teeth, pieces of jaws, hind limbs and body armour, all of which are can be described as parts of rauisuchians.
Rauisuchians are closely related to crocodiles as we know them today. They had a diversity of body shapes and sizes during the Triassic period. The specimens described in this research include some of the largest carnivorous members of this group, that were possibly up to 10 metres long, with huge skulls full of serrated, curved teeth.
The study, published online in the Journal of African Earth Sciences last week, shows that the rauisuchians were some of the latest-surviving members of their group, and that when they were alive, they were thriving close to the Antarctic Circle — the theoretical limit for their physiology.
“In the Triassic period, rauisuchians were widespread and their fossils are known from all continents except Antarctica,” adds Tolchard. “They went extinct about 200 million years ago, paving the way for dinosaurs to become the dominant large land animals.”
“Rick’s study demonstrates the value of re-examining old specimens, and now we finally know what was preying on all those herbivorous dinosaurs!” says Professor Jonah Choiniere, Rick’s advisor and Professor of Comparative Palaeobiology at the Wits Evolutionary Studies Institute.
Tolchard studied fossils from collections based at the the University of the Witwatersrand, the Iziko South African Museum and the National Museum in Bloemfontein. He was joined in the research by an international team, including researchers from the USA, Argentina and the UK.
Reference:
Frederick Tolchard, Sterling J. Nesbitt, Julia B. Desojo, Pia Viglietti, Richard J. Butler, Jonah N. Choiniere. ‘Rauisuchian’ material from the lower Elliot Formation of South Africa and Lesotho: Implications for Late Triassic biogeography and biostratigraphy. Journal of African Earth Sciences, 2019; 160: 103610 DOI: 10.1016/j.jafrearsci.2019.103610
An artist’s rendition of the Tyrannosaurus rex with the 3D imaging showing muscle activation in its head. Illustration courtesy of Brian Engh.
A Tyrannosaurus rex could bite hard enough to shatter the bones of its prey. But how it accomplished this feat without breaking its own skull bones has baffled paleontologists. That’s why scientists at the University of Missouri are arguing that the T. rex’s skull was stiff much like the skulls of hyenas and crocodiles, and not flexible like snakes and birds as paleontologists previously thought.
“The T. rex had a skull that’s 6 feet long, 5 feet wide and 4 feet high, and bites with the force of about 6 tons,” said Kaleb Sellers, a graduate student in the MU School of Medicine. “Previous researchers looked at this from a bone-only perspective without taking into account all of the connections — ligaments and cartilage — that really mediate the interactions between the bones.”
Using a combination of imaging, anatomy and engineering analysis, the team observed how the roof of the mouth of the T. rex reacted to the stresses and strains from chewing by applying models of how two present day relatives of T. rex — a gecko and a parrot — chew to how the T. rex skull worked.
“Dinosaurs are like modern-day birds, crocodiles and lizards in that they inherited particular joints in their skulls from fish — ball and socket joints, much like people’s hip joints — that seem to lend themselves, but not always, to movement like in snakes,” said Casey Holliday, an associate professor of anatomy in the MU School of Medicine. “When you put a lot of force on things, there’s a tradeoff between movement and stability. Birds and lizards have more movement but less stability. When we applied their individual movements to the T. rex skull, we saw it did not like being wiggled in ways that the lizard and bird skulls do, which suggests more stiffness.”
In addition to helping paleontologists with a detailed study of the anatomy of fossilized animals, researchers believe their findings can help advance human and animal medicine by providing better models of how joints and ligaments interact.
“In humans, this can also be applied to how people’s jaws work, such as studying how the jaw joint is loaded by stresses and strains during chewing,” said Ian Cost, the lead researcher on the study. Cost is an assistant professor at Albright College and a former doctoral student in the MU School of Medicine. “In animals, understanding how those movements occur and joints are loaded will, for instance, help veterinarians better understand how to treat exotic animals such as parrots, which suffer from arthritis in their faces.”
Reference:
Ian N. Cost, Kevin M. Middleton, Kaleb C. Sellers, Michael Scott Echols, Lawrence M. Witmer, Julian L. Davis, Casey M. Holliday. Palatal Biomechanics and Its Significance for Cranial Kinesis in Tyrannosaurus rex. The Anatomical Record, 2019; DOI: 10.1002/ar.24219
Yellowstone National Park is an American national park located in Wyoming, Montana, and Idaho.
Places To Visit in United States of America
In this Article you will find some of the best natural Places To Visit in United States of America
1. Devils Tower, Wyoming
Devils Tower. Photo Copyright: Wikipedia
Devils Tower (also recognized as Bear Lodge Butte) is a butt, potentially laccolithic, made up of igneous rock in the Black Hills Bear Lodge Ranger District, close Hulett and Sundance in Crook County, northeast of Wyoming, overlooking the Belle Fourche River. It rises above the Belle Fourche River at 1,267 feet (386 m), sitting at 867 feet (265 m) from top to bottom. The peak is 5,112 feet above sea level (1,559 m).
Devils Tower was the first National Monument to be founded by President Theodore Roosevelt on September 24, 1906. The border of the monument encompasses an area of 1,347 acres (545 ha).
Approximately 1% of the 400,000 annual tourists to the monument have visited the Devils Tower in latest years, mostly using traditional climbing methods and it is the best place to visit in united states of america.
The name Devil’s Tower arose during an expedition led by Colonel Richard Irving Dodge in 1875, when his translator allegedly misinterpreted a indigenous word meaning “Bad God’s Tower.” All data advertisements in that region use the word “Devils Tower,” following a norm of geographical naming that omits the apostrophe.
2. The Wave, Arizona
The Wave – Arizona
The Wave is a sandstone rock formation situated close its southern boundary with Utah in Arizona, United States. The structure is located on the Coyote Buttes hills in the Colorado Plateau’s Paria Canyon-Vermilion Cliffs Wilderness. The region is managed at the Grand Staircase-Escalante National Monument Visitor Center in Kanab, Utah by the Land Management Bureau (BLM).
Among hikers and photographers, the structure is well known for its colourful, ondulating shapes and the hard walk needed to achieve it and this is one of the best Places To Visit in United States of America. Because of the brittle nature of the training and the big amount of individuals wanting to attend it, the Kanab Visitor Center uses a regular lottery scheme to issue only ten licenses next day in individual. Furthermore, ten internet licenses are accessible four months prior to a scheduled journey for each date. Those who have acquired licenses will receive a map and data about the walk.
The Wave is made up of intersecting U-shaped troughs eroded into Jurassic age Navajo Sandstone. The two main stone forming troughs are 62 feet (19 m) wide by 118 feet (36 m) lengthy and 52 feet (16 m) broad by 7 feet (2 m). Initially, these troughs along joints within the Navajo Sandstone were eroded by rare runoff. The drainage basin, which supplied rainwater to these troughs, shrank after their creation to the stage that the runoff became inadequate to help cut these troughs.
3. Antelope Canyon, Arizona
Antelope Canyon
Antelope Canyon is an American Southwest slot canyon. It’s on the west of Page, Arizona, Navajo territory. Antelope Canyon involves two distinct, picturesque canyon slot segments, separately referred to as ‘ Upper Antelope Canyon ‘ or ‘ The Crack ; ‘ and ‘ Lower Antelope Canyon ‘ or ‘ The Corkscrew. ‘
Tsé bighánílíní is the name Navajo for the Upper Antelope Canyon, which implies’ the location where water passes through trees.’ The Lower Antelope Canyon is the Navajo Parks and Recreation Department’s Hazdistazí (called “Hasdestwazi”), or’ spiral stone arches.’ Both are in the Navajo Nation’s LeChee Chapter. The canyons can only be accessed through a guided trip, This is a best place to feel happy and joy so it is one of best of Places To Visit in United States of America.
Navajo Sandstone erosion created the Antelope Canyon, mainly owing to flash flooding and secondary owing to other sub-aerial procedures. Rainwater flows into the expansive basin above the slot canyon segments, particularly during the monsoon season, picking up velocity and sand as it flows through the tight passages. The passages deteriorated over moment, deepening the hallways and brushing difficult corners in such a manner that distinctive “flowing” forms in the rock were formed.
4. Dry Tortugas National Park, Florida
Dry Tortugas National Park
Dry Tortugas National Park is about 68 miles (109 km) south of Key West in the Gulf of Mexico, a national park in the United States. The park retains Fort Jefferson and the seven islands of Dry Tortugas, the Florida Keys ‘ most remote and westernmost. The coral reefs of the archipelago are the least damaged of the reefs of Florida Keys.
The park is known for its abundant marine life, tropical bird breeding grounds, colourful coral reefs, shipwreck myths and sunken treasures. Fort Jefferson, a huge but incomplete coastal fortification, is the centerpiece of the park. Fort Jefferson is the Western Hemisphere’s biggest brick masonry structure, consisting of over 16 million bricks. Only Fort Monroe, Virginia, and Fort Adams, Rhode Island, exceed it in size among U.S. bases. Dry Tortugas is distinctive in its mixture with important historical artifacts of a mainly undisturbed tropical ecosystem.
The park is only accessible by seaplane or boat and has an average of approximately 63,000 visitors per year between 2008 and 2017. Snorkeling, picnicking, bird watching, hiking, scuba diving, fishing for saltwater and kayaking are some of the activities.
Dry Tortugas National Park is part of the Biosphere Reserve of Everglades & Dry Tortugas, established by UNESCO under its Man and Biosphere Program in 1976.
5. Yellowstone National Park, Wyoming, Montana, and Idaho
Yellowstone National Park is an American national park located in Wyoming, Montana, and Idaho.
Yellowstone National Park is a Wyoming, Montana, and Idaho American domestic park. It was set up by the U.S. Congress and President Ulysses S. Grant entered it into law on March 1, 1872. Yellowstone was the first national park in the U.S. and the first national park in the globe is also commonly kept. The park is renowned for its wildlife and numerous geothermal features, including Old Faithful Geyser, one of its most famous characteristics. It has many kinds of ecosystems, but the most common is the subalpine forest. It is component of the ecoregion of the South Central Rockies forests “Amazing places to visit in united states of america”.
Native Americans have resided for at least 11,000 years in the Yellowstone region. During the early-to-mid-19th century, apart from trips by mountain men, structured exploring did not start until the early 1860s. Originally, park management and control falls within the jurisdiction of the Interior Secretary, the first being Columbus Delano. But the U.S. Subsequently, the Army was commissioned to oversee Yellowstone management for a period of 30 years from 1886 to 1916.
Yellowstone is on the southeastern edge of the Snake River Plain, a large U-shaped curve through the hills stretching from Boise, Idaho about 400 miles (640 km) south.
Yellowstone volcanism is thought to be related to the Snake River plain’s somewhat earlier volcanism. Thus, Yellowstone is the active component of a hotspot that over time has shifted south. The source of this volcanic hotspot is controversial. One hypothesis argues that a mantle plume led the Yellowstone hotspot to migrate south, while another hypothesis explains migrating hotspot volcanism as a consequence of the fragmentation and dynamics of the subdued Farallon Plate in the middle of Earth.
The Yellowstone Caldera is North America’s biggest volcanic scheme. It was called a “supervolcano” because extremely big explosive eruptions created the caldera. It is projected that the magma chamber below Yellowstone is a single linked tank, approximately 37 miles (60 km) long, 18 miles (29 km) broad and 3 to 7 miles (5 to 12 km) depth.
6. Haiku Stairs of Oahu, Hawaii
Haiku Stairs of Oahu, Hawaii
The Haalikū Stairs, also referred as the Heaven Stairway or Haalikū Ladder, is a challenging walking path on Hawaii’s island of Oalmahu. The total of 3,922 steps cover the mountain range of Oahu’s Ko’olau. “Haiku” refers not to the poetry genre of Japan. The region is named after the Kahili flower “Ha regikū.”
Contractors for the United States in 1942 Navy started the development of the Haferikū Radio Station, a top secret unit to be used to convey radio signals to Navy vessels then working across the Pacific. In order to obtain the necessary height for the antennae, they were stretched by the Navy across the natural amphitheater, Haifikū Valley. In addition to the metal steps, some remaining sections of the wooden ladder can still be seen.
7. Hamilton Pool, Texas
Hamilton Pool, Texas. Flickr: dawilson / Creative Commons
Hamilton Pool Preserve is a natural pool that was formed as a result of huge erosion thousands of years earlier when an underground river dome crashed. Around 23 miles (37 km) north of Austin, Texas off Highway 71, the pool is situated. Hamilton Pool has been a famous summer swimming place for tourists and inhabitants of Austin since the 1960s. Hamilton Pool Preserve is a preserved natural habitat of 232 acres (0.94 km2) with a jade green pool in which a 50-foot (15 m) waterfall flows with water temperatures exceeding 50 degrees Fahrenheit.
The pond is enclosed by big calcareous rocks that lie at the bottom of the water; big stalactites develop from the top of the roof. Moss, maidenhair fern and cliff swallows are close to the grotto’s roof and adjacent hills. The preserve’s Ashe juniper (cedar) uplands are home to the endangered warbler golden-cheeked.
There is no chemical treatment of the natural pool and creek, so water quality is constantly tracked and swimming is sometimes limited. Hamilton Pool is a protected area, part of the Balcones Canyonlands Preserve.
8. Horseshoe Bend, Arizona
Horseshoe Bend, Arizona
Horseshoe Bend is a Colorado River incised horseshoe meander close the city of Page, Arizona, USA, This is from the best places to visit in united states of america.
Horseshoe Bend is situated in the Glen Canyon National Recreation Area, about 4 miles (6.4 km) southeast of Page, 5 miles (8.0 km) upstream from the Glen Canyon Dam and Lake Powell.
It is available from a parking area near the U.S. by walking a 1.5-mile (2.4 km) round journey. Route 89 on the southwest side of Page.
From the steep cliff above, you can see Horseshoe Bend.
The view is 4,200 feet (1,300 m) above sea level, and the Colorado River is 3,200 feet (980 m) above sea level, resulting in a fall of 1,000 feet (300 m).
The lookout has recently become a significant place for tourists. By 2018, social media place mentions had prompted a significant rise in the amount of tourists.
9. Bryce Canyon, Utah
Bryce Canyon (Credit: Luca Galuzzi, CC by 2.5)
Bryce Canyon National Park is an American domestic park in southeastern Utah. The park’s main characteristic is Bryce Canyon, which is not a canyon despite its title, but a series of gigantic natural amphitheaters along the Paunsaugunt Plateau’s southern edge. Bryce is characteristic because of the geological structures called hoodoos, which are created by frost weathering and river and lake bed erosion of sedimentary rocks. The rocks ‘ red, orange, and white colours provide park tourists with amazing opinions. Bryce Canyon National Park is much lower than neighboring Zion National Park and lies at a much higher elevation. The rim at Bryce varies from 8,000 to 9,000 feet (2,400 to 2,700 m).
The area of Bryce Canyon was settled in the 1850s by Mormon pioneers and was named after Ebenezer Bryce, who in 1874 lived in the area. Originally appointed as a national monument by President Warren G. Harding in 1923, the region around Bryce Canyon was redesigned by Congress in 1928 as a national park.
The park includes 35,835 acres (55,992 sq mi; 14,502 ha; 145,02 km2) and gets significantly fewer tourists than Zion National Park (approximately 4.3 million in 2016) or Grand Canyon National Park (approximately 6 million in 2016), owing mainly to the more distant place of Bryce. Bryce Canyon got 2,365,110 recreational tourists in 2016, a 35 percent boost from the previous year.
10. Lake Tahoe, California/Nevada
Lake Tahoe, California/Nevada
Lake Tahoe in the U.S. Sierra Nevada is a big freshwater lake. Situated at 6,225 ft (1,897 m) south of Carson City, it straddles the state boundary between California and Nevada. Lake Tahoe is North America’s biggest alpine lake and passes only the five Great Lakes as the biggest by quantity in the United States at 122,160,280 acres (150.7 km3). Its elevation is 501 m (1,645 ft), making it the second longest in the United States after Oregon’s Crater Lake (1,949 ft or 594 m).
The lake was created as portion of the Lake Tahoe Basin about two million years ago, shaping the contemporary magnitude during the ice ages. It is renowned on all sides for the clearness of its water and the panorama of neighboring hills. Also known as Lake Tahoe, or merely Tahoe, is the region surrounding the lake. More than 75% of the lake’s catchment is domestic forest property, which includes the U.S. Forest Service’s Lake Tahoe Basin Management Unit so this is one of Places To Visit in United States of America.
Lake Tahoe is one of Nevada and California’s main tourist attractions. It is home to year-round winter sports, indoor summer recreation, and landscapes. Snow and ski resorts are a major component of the economy and reputation of the area. Several lakeside casino casinos are also available on the Nevada hand, with roads offering year-round access to the whole region.
11. Badlands National Park, South Dakota
Badlands National Park, South Dakota
Badlands National Park is a national park in the southwest of South Dakota. In addition to the biggest undisturbed mixed grass prairie in the United States, the park protects 242,756 acres (379.3 sq mi; 982.4 km2) of significantly eroded buttes and pinnacles. The park is managed by the National Park Service, with the South Unit co-managed by the tribe of Oglala Lakota, from the best places to visit in united states of america.
The Badlands Wilderness preserves the park’s 64,144 acres (100.2 sq mi; 259.6 km2) as a specified wildlife area, and is one location where the black-footed ferret, one of the world’s most endangered mammals, has been brought into the wild. The South Unit, or Stronghold District, includes sites of 1890s Ghost Dances, a former U.S. Air Force bomb and gunnery range, and Red Shirt Table, the highest point of the park at 1,020 m (3,340 feet).
It was not established until January 25, 1939, authorized as the Badlands National Monument on March 4, 1929. On November 10, 1978, Badlands was redesigned as a national park. The Ben Reifel Visitor Center was built for the memorial in 1957–58 under the Mission 66 scheme. The monument also administers the National Historic Site of the neighboring Minuteman Missile. Partially filmed in Badlands National Park were films such as Dances with Wolves (1990) and Thunderheart (1992).
12. Palouse Falls, Washington
Palouse Falls, Washington
The Palouse Falls are located on the Palouse River, approximately 4 miles (6 km) downstream of the Snake River confluence in southeast Washington, USA. The height of the drops is 198 ft (60 m). The hills comprise of an upper drop with a drop of about 20 ft (6.1 m), 1000 ft (305 m) north-northwest of the primary drop, and a smaller drop with a drop of 198 ft (60 m).
The canyon at the cliffs is 115 m (377 ft) profound, showing the Columbia River Basalt Group’s big cross-section. These hills and the upstream canyon are an significant characteristic of the channeled scablands formed during the Pleistocene era by the huge rains of Missoula that periodically spread across eastern Washington and across the plateau of the Columbia River is amazing Waterfall you must visit in Places To Visit in United States of America.
The ancient river Palouse flowed to the Columbia River through the presently dry Washtucna Coulee. The Palouse Falls and adjacent canyons were formed when the Missoula floods overturned the ancient Palouse River’s southern valley wall, diverting it by erosion of a fresh channel to the present route to the Snake River.
The region is distinguished by interconnected and suspended flood-created coulees, cataracts, diving basins, kolk-created potholes, rock benches, buttes, and typical scabulary pinnacles. Palouse Falls State Park is situated at the falls, preserving this unique portion of the picturesque region.
13. Nā Pali Coast State Park, Hawaii
Nā Pali Coast State Park, Hawaii
The Nā Pali Coast State Park is a Hawaiian national park of 6,175 acres (2,499 ha) situated in the middle of the hilly 16 miles (26 km) along Kauai’s southwest coast, the longest inhabited Hawaiian island. The coast of Nā Pali itself stretches southeast from Kee Beach to Polihale State Park. The na bari (elevated hills) rise above the Pacific Ocean as elevated as 4,000 feet (1,200 m) along the coast. To safeguard the Kalalau Valley, the State Park was created.
The Hono O Nā Pali State Natural Reserve is located to the south of the national park. It was set up in 1983 and expanded in 2009 to more than 3,578 acres (14.5 km2). Hiking paths and highways for visitors in Waimea Canyon have access to the steep slopes from Koke’e Road (route 550).
14. Glacier National Park, Montana
Glacier National Park
Glacier National Park is an American national park situated on the Canada-U.S. border in southeastern Montana, close to Alberta and British Columbia regions of Canada. The park covers more than 1 million acres (4,000 km2) and contains sections of two mountain ranges (the Rocky Mountains sub-ranges), more than 130 named lakes, more than 1,000 distinct plant species, and hundreds of animal species. This vast untouched ecosystem is at the center of what has been called the “Crown of the Continent Ecosystem,” an area of 16,000 square miles (41,000 km2) of protected territory.
Native Americans first populated the region that became the Glacier National Park. When European explorers arrived, it was dominated in the east by the Blackfeet and in the west by the Flathead. Under stress, the Blackfeet surrendered to the federal government in 1895 the hilly sections of their treaty lands; it subsequently became component of the park. Soon after the park was set up on May 11, 1910, the Great Northern Railway built a range of accommodations and chalets.
15. Thor’s Well, Oregon
Thor’s Well, Oregon
There is a natural cave on the shore of Oregon that seems to drain the ocean.
At high tide, or during floods, the place is most impressive when water washes violently over the rocks and funnels into the cave. Unattended tourists to the site run the danger of being thrown straight into the maelstrom during these sudden torrents. Photographers and nature enthusiasts proceed to flock to the magnificent fountain, regardless of the hazards, to see the hostile waters that live up to the stormy character of their godly namesake. The best time to check Thor’s Well is to watch it without water one hour before the high tide and then watch the structure fill up.
16. Sequoia National Park, California
Sequoia National Park
Sequoia National Park in the central Sierra Nevada south of Visalia, California, is an American national park. The reserve was created on September 25, 1890 to safeguard 404,064 acres of wooded hilly land (631 sq mi; 163,519 ha; 1,635 km2). The park includes the highest point in the contiguous United States, Mount Whitney, at 14,505 feet (4,421 m) above sea level, covering a vertical relief of nearly 13,000 feet (4,000 m).
The park is north of and adjacent to Kings Canyon National Park ; the two areas are administered as Sequoia and Kings Canyon National Parks by the National Park Service together. The Sequoia-Kings Canyon Biosphere Reserve was named by UNESCO in 1976.
The park is noteworthy for its giant sequoia forests, including the General Sherman tree, Earth’s biggest tree. In the Giant Forest, which includes five of the world’s ten largest trees, the General Sherman tree develops. The Giant Forest is linked to General Grant Grove, home of the General Grant tree among other giant sequoias, by the Generals Highway to Kings Canyon National Park.
17. Niagara Falls, New York
Niagara Falls, New York
Niagara Falls is a town in the county of Niagara, New York, USA. The town had a complete population of 50,193 as of the 2010 census, down from the 55,593 reported in the census of 2000. It is close to the Niagara River, across from Niagara Falls City, Ontario, and named after the well-known Niagara Falls they share. The town is located within the Metropolitan Statistical Area of Buffalo–Niagara Falls and the West New York area, This is from amazing places to visit in united states of america.
While the town was formerly occupied by Native Americans, Europeans who moved in the mid-17th century to the Niagara Falls started opening up companies and developing infrastructure. Scientists and entrepreneurs later started to harness the capacity of the Niagara River for electricity in the 18th and 19th decades, and the town started to attract producers and other companies attracted by the offer of cheap hydroelectric power. However, following an effort at urban renewal under then-Mayor Lackey, the town and region experienced an financial decrease after the 1960s.
18. Great Smoky Mountains, North Carolina/Tennessee
Great Smoky Mountains, North Carolina/Tennessee
The Great Smoky Mountains are a hill range that rises in the southern United States along the Tennessee–North Carolina boundary. They are an Appalachian Mountains sub-range and are component of the Physiographic Province of the Blue Ridge. Sometimes the range is called the Smoky Mountains and the name is usually abbreviated to the Smokies. The Great Smokies are best regarded as the headquarters of the National Park of the Great Smoky Mountains, protecting most of the area. Established in 1934, the park is the most visited national park in the United States with over 11 million visits per year.
The Great Smokies are component of a Biosphere Reserve International. The range is home to an approximately 76,000 ha (187,000 acres) of old growth forest, the biggest such cluster to be found west of the Mississippi River. One of the most varied ecosystems in North America is the cove hardwood forests in the reduced altitudes of the range, and the Southern Appalachian spruce-fir forest that covers the upper parts of the range is the biggest of its kind. The Great Smokies are also home to the Eastern United States ‘ densest black bear population and the most varied salamander community outside the tropics.
19. Northern Lights, Alaska
Northern Lights, Alaska
While many tourists believe they must go to Europe to see the Northern Lights, you can truly see this phenomenon without abandoning the United States. There are many Americans heading for the opportunity to see the aurora borealis in northern Alaska. It may be cold in winter (temperatures may drop to-30 ° F), but coastal Alaskan Arctic— where skies tend to be clearer— is one of the world’s greatest locations to see this renowned light display.
20. Carlsbad Caverns, New Mexico
Carlsbad Caverns, New Mexico
Carlsbad Caverns National Park is an American National Park in southern New Mexico’s Guadalupe Mountains. The park’s main attraction is the Carlsbad Cavern show cave. Visitors to the cave can walk or bring an elevator from the visitor center on their own through the natural door.
On US Highway 62/180, about 18 miles (29 km) southeast of Carlsbad, New Mexico, the park gate is situated. The National Park of Carlsbad Caverns is involved in the Junior Ranger Program. The reserve has two listings on the Historic Places National Register: the Historic District of Caverns and the Historic District of Rattlesnake Springs. Approximately two-thirds of the park has been laid aside as a wilderness area to help guarantee that future habitat modifications are not created.
Carlsbad Cavern contains a big room of calcareous, merely called the Big Room, which is nearly 4,000 feet (1,220 m) long, 625 feet (191 m) broad, and at its lowest level, 255 feet (78 m). The Big Room is North America’s third biggest chamber and the world’s twenty-eighth biggest.
This image shows the divisions between Earth’s layers. The ancient, continent-sized rock regions encircle the liquid outer core. Credit: Lawrence Livermore National Laboratory
Ancient, distinct, continent-sized regions of rocks, isolated since before the collision that created the Moon 4.5 billion years ago, exist hundreds of miles below the Earth’s crust, offering a window into the building blocks of our planet, according to new research.
The new study in the AGU Journal Geochemistry, Geophysics, Geosystems used models to trace the location and origin of volcanic rock samples found throughout the world back to two solid continents in the deep mantle. The new research suggests the specific giant rock regions have existed for 4.5 billion years, since Earth’s beginning.
Previously, scientists theorized that separated continents in the deep mantle came from subducted oceanic plates. But the new study indicates these distinct regions may have been formed from an ancient magma ocean that solidified during the beginning of Earth’s formation and may have survived the massive Moon-creating impact.
Determining the masses’ origin reveals more details about their evolution and composition, as well as clues about primordial Earth’s history in the early Solar System, according to the study’s authors.
It’s amazing that these regions have survived most of Earth’s volcanic history relatively untouched, said Curtis Williams, a geologist at the University of California, Davis, in Davis, California and lead author of the study.
Looking inward
The mantle is a layer of rock, stretching 2,900 kilometers (1,802 miles) down inside the Earth. Earth’s molten, liquid, metallic core lies beneath the mantle. The core-mantle boundary is where the solid mantle meets the metallic liquid core.
Scientists knew from past seismic imaging studies that two individual rock bodies existed near the core-mantle boundary. One solid rock body is under Africa and the other is under the Pacific Ocean.
Seismic waves, the vibrations produced by earthquakes, move differently through these masses than the rest of the mantle, suggesting they have distinct physical properties from the surrounding mantle. But geologists couldn’t determine whether seismic waves moved differently through the core-mantle continents because of differences in their temperature, mineral composition or density, or some combination of these properties. That meant they could only hypothesize about the separate rocky masses’ origin and history.
“We had all of these geochemical measurements from Earth’s surface, but we didn’t know how to relate these geochemical measurements to regions of Earth’s interior. We had all of these geophysical images of the Earth’s interior, but we didn’t know how to relate that to the geochemistry at Earth’s surface,” Williams said.
Primitive material and plumes
Williams and his colleagues wanted to determine the distinct masses’ origin and evolution to learn more about Earth’s composition and past. To do this, they needed to be able to identify samples at Earth’s surface with higher concentrations of primitive material and then trace those samples back to their origins.
Scientists often take rock samples from volcanic regions like Hawaii and Iceland, where deep mantle plumes, or columns of extremely hot rock, rise from the areas near the core, melt in the shallow mantle and emerge far from tectonic fault lines. These samples are made of igneous rock created from cooling lava. The study’s authors used an existing database of samples and also collected new samples from volcanically active areas like the Balleny Islands in Antarctica.
Geologists can measure specific isotopes in igneous rocks to learn more about the origin and evolution of the Earth. Some isotopes, like Helium-3, are primordial, meaning they were created during the Big Bang. Rocks closer to Earth’s crust have less of the isotope than rocks deeper underground that were never exposed to air. Samples with more Helium-3 are thought to come from more primitive rocks in the mantle.
The researchers found some of the samples they studied had more Helium-3, indicating they may have come from primitive rocks deep in the Earth’s mantle.
The researchers then used a new model to trace how these primitive samples could have gotten to the Earth’s surface from the mantle. Geological models assume plumes rise vertically from deep within the mantle to the Earth’s surface. But plumes can move off course, deflected, due to various reasons. The new model took into account this plume deflection, allowing the study’s authors to trace the samples back to the two giant masses near the core-mantle boundary.
The combination of the isotope information and the new model allowed the researchers to determine the composition of the two giant masses and theorize how they may have formed.
Understanding the composition of specific rock masses near the core-mantle boundary helps geologists conceptualize ancient Earth-shaping processes that led to the modern-day mantle, according to the study’s authors.
“It’s a more robust framework to try and answer these questions in terms of not making these assumptions of vertically rising material but rather to take into account how much deflection these plumes have seen,” Williams said.
Reference:
C. D. Williams et al. Primitive Helium Is Sourced From Seismically Slow Regions in the Lowermost Mantle, Geochemistry, Geophysics, Geosystems (2019). DOI: 10.1029/2019GC008437
Note: The above post is reprinted from materials provided by American Geophysical Union. The original article was written by Abigail Eisenstadt .
A tiny sample of goldschmidtite found inside a diamond by U of A PhD student Nicole Meyer. The newly discovered mineral has high concentrations of elements seldom found in Earth’s mantle, suggesting it formed under extreme conditions. Credit: Nicole Meyer
A Ph.D. student at the University of Alberta has discovered a new and curious mineral inside a diamond unearthed from a mine in South Africa.
The mineral—named goldschmidtite in honor of Victor Moritz Goldschmidt, the founder of modern geochemistry—has an unusual chemical signature for a mineral from Earth’s mantle, explained Nicole Meyer, a graduate student in the Diamond Exploration Research and Training School.
“Goldschmidtite has high concentrations of niobium, potassium and the rare earth elements lanthanum and cerium, whereas the rest of the mantle is dominated by other elements, such as magnesium and iron,” said Meyer.
“For potassium and niobium to constitute a major proportion of this mineral, it must have formed under exceptional processes that concentrated these unusual elements.”
The researchers estimate the diamond containing the goldschmidtite formed about 170 kilometers beneath Earth’s surface, at temperatures reaching nearly 1,200 C.
Because it is so difficult to drill down through Earth’s crust to reach the mantle, scientists rely on tiny mineral inclusions within diamonds to learn more about Earth’s chemistry deep beneath the surface.
“(The discovery) gives us a snapshot of fluid processes that affect the deep roots of continents during diamond formation,” said Meyer’s co-supervisor, Graham Pearson, who added there have been several attempts to name new minerals after Goldschmidt, but previous ones have been discredited. “This one is here to stay.”
“The work that goes into finding a new mineral is not done by one person,” said Meyer, who is also studying under the supervision of Thomas Stachel, professor and Canada Research Chair in Diamonds. “It has been an interdisciplinary collaboration with mineralogist Andrew Locock, crystallographers from Northwestern University, my advisers Thomas and Graham, and technicians.”
The study, “Goldschmidtite, (K,REE,Sr)(Nb,Cr)O3: a New Perovskite Supergroup Mineral Found in Diamond from Koffiefontein, South Africa,” was published in American Mineralogist.
Reference:
Nicole A. Meyer et al. Goldschmidtite, (K,REE,Sr)(Nb,Cr)O3: A new perovskite supergroup mineral found in diamond from Koffiefontein, South Africa, American Mineralogist (2019). DOI: 10.2138/am-2019-6937
Illustration of the giant asteroid collision in outer space that produced the dust that led to an ice age on Earth. Credit: (c) Don Davis, Southwest Research Institute
About 466 million years ago, long before the age of the dinosaurs, the Earth froze. The seas began to ice over at the Earth’s poles, and the new range of temperatures around the planet set the stage for a boom of new species evolving. The cause of this ice age was a mystery, until now: a new study in Science Advances argues that the ice age was caused by global cooling, triggered by extra dust in the atmosphere from a giant asteroid collision in outer space.
There’s always a lot of dust from outer space floating down to Earth, little bits of asteroids and comets, but this dust is normally only a tiny fraction of the other dust in our atmosphere such as volcanic ash, dust from deserts and sea salt. But when a 93-mile-wide asteroid between Mars and Jupiter broke apart 466 million years ago, it created way more dust than usual. “Normally, Earth gains about 40,000 tons of extraterrestrial material every year,” says Philipp Heck, a curator at the Field Museum, associate professor at the University of Chicago, and one of the paper’s authors. “Imagine multiplying that by a factor of a thousand or ten thousand.” To contextualize that, in a typical year, one thousand semi trucks’ worth of interplanetary dust fall to Earth. In the couple million years following the collision, it’d be more like ten million semis.
“Our hypothesis is that the large amounts of extraterrestrial dust over a timeframe of at least two million years played an important role in changing the climate on Earth, contributing to cooling,” says Heck.
“Our results show for the first time that such dust, at times, has cooled Earth dramatically,” says Birger Schmitz of Sweden’s Lund University, the study’s lead author and a research associate at the Field Museum. “Our studies can give a more detailed, empirical-based understanding of how this works, and this in turn can be used to evaluate if model simulations are realistic.”
To figure it out, researchers looked for traces of space dust in 466-million-year-old rocks, and compared it to tiny micrometeorites from Antarctica as a reference. “We studied extraterrestrial matter, meteorites and micrometeorites, in the sedimentary record of Earth, meaning rocks that were once sea floor,” says Heck. “And then we extracted the extraterrestrial matter to discover what it was and where it came from.”
Extracting the extraterrestrial matter — the tiny meteorites and bits of dust from outer space — involves taking the ancient rock and treating it with acid that eats away the stone and leaves the space stuff. The team then analyzed the chemical makeup of the remaining dust. The team also analyzed rocks from the ancient seafloor and looked for elements that rarely appear in Earth rocks and for isotopes — different forms of atoms — that show hallmarks of coming from outer space. For instance, helium atoms normally have two protons, two neutrons, and two electrons, but some that are shot out of the Sun and into space are missing a neutron. The presence of these special helium isotopes, along with rare metals often found in asteroids, proves that the dust originated from space.
Other scientists had already established that our planet was undergoing an ice age around this time. The amount of water in the Earth’s oceans influences the way that rocks on the seabed form, and the rocks from this time period show signs of shallower oceans — a hint that some of the Earth’s water was trapped in glaciers and sea ice. Schmitz and his colleagues are the first to show that this ice age syncs up with the extra dust in the atmosphere. “The timing appears to be perfect,” he says. The extra dust in the atmosphere helps explain the ice age — by filtering out sunlight, the dust would have caused global cooling.
Since the dust floated down to Earth over at least two million years, the cooling was gradual enough for life to adapt and even benefit from the changes. An explosion of new species evolved as creatures adapted for survival in regions with different temperatures.
Heck notes that while this period of global cooling proved beneficial to life on Earth, fast-paced climate change can be catastrophic. “In the global cooling we studied, we’re talking about timescales of millions of years. It’s very different from the climate change caused by the meteorite 65 million years ago that killed the dinosaurs, and it’s different from the global warming today — this global cooling was a gentle nudge. There was less stress.”
It’s tempting to think that today’s global warming could be solved by replicating the dust shower that triggered global cooling 466 million years ago. But Heck says he would be cautious: “Geoengineering proposals should be evaluated very critically and very carefully, because if something goes wrong, things could become worse than before.”
While Heck isn’t convinced that we’ve found the solution to climate change, he says it’s a good idea for us to be thinking along these lines.
“We’re experiencing global warming, it’s undeniable,” says Heck. “And we need to think about how we can prevent catastrophic consequences, or minimize them. Any idea that’s reasonable should be explored.”
Reference:
Birger Schmitz, Kenneth A. Farley, Steven Goderis, Philipp R. Heck, Stig M. Bergström, Samuele Boschi, Philippe Claeys, Vinciane Debaille, Andrei Dronov, Matthias Van Ginneken, David A.t. Harper, Faisal Iqbal, Johan Friberg, Shiyong Liao, Ellinor Martin, Matthias M. M. Meier, Bernhard Peucker-Ehrenbrink, Bastien Soens, Rainer Wieler and Fredrik Terfelt. An extraterrestrial trigger for the mid-Ordovician ice age: Dust from the breakup of the L-chondrite parent body. Science Advances, 2019 DOI: 10.1126/sciadv.aax4184
Photographs of alkaline magmatic intrusions in Greenland. The region was volcanically and tectonically active around 1.2 billion years ago. Although no longer active, it is of major interest to geologists because the subsequent uplift and glacial erosion have cut deep into the rift and exposed the magma chambers that once lay well below the surface. Greenland’s magmas were sourced from a mantle that was enriched and contaminated by ancient crustal materials. Credit: University of St Andrews
Ancient volcanoes dating back billions of years could provide new insights into how the Earth’s surface is recycled, according to scientists at the University of St Andrews.
A study, published today in Nature Communications, reveals the fate of the Earth’s ancient crust and could help solve the mystery of how the Earth’s surface and mantle are connected.
The Earth’s outermost layer is made up of rigid tectonic plates which move around and collide at regions called subduction zones.
In areas of collision, crustal materials get transported into the deep mantle, and one of the grand challenges in Earth Sciences is to understand what happens to this crust and how long it resides in the mantle.
At a few volcanoes on Earth geologists can find traces of these ancient crustal materials in the erupted lava. To date most of this work has focused on oceanic islands like Hawaii or the Canaries.
However, oceanic islands are only present at the surface of the Earth for a few million years before they themselves subside and are subducted back into the mantle, and so can only provide a tiny snapshot of crustal recycling over the four billion years of Earth history.
The St Andrews team investigated a suite of alkaline magmas erupted in continental rifts similar to the modern day East African rift.
Although these magmas have very unusual chemistries, they show many similarities with those oceanic lavas and, crucially, are found throughout Earth’s geological record.
The team focused on an alkaline province in south-west Greenland using cutting-edge isotope techniques to chemically fingerprint ancient crustal material in the source of these magmas.
Through a combination of remote field work (by boat and helicopter) and careful chemical analysis the team was able to show that these magmas were tapping into ancient crust subducted into the mantle 500 million years before the volcanoes started erupting.
Once the team understood these processes in Greenland they compiled a global data on alkaline magma chemistry and were surprised to find that the vast majority contained a recycled crustal component in their magma source.
Lead author Dr. Will Hutchison, from the School of Earth and Environmental Sciences at the University, said: “Our key result is that the isotopes of alkaline magmas are highly variable and this suggests that their recycled crustal sources have changed through geological time.
“The beauty of our global dataset is that it extends back over two billion years and so these unique alkaline rocks represent an extremely powerful record for understanding crustal recycling over Earth history.”
“By carefully bringing together the igneous and sedimentary isotope records, this might allow us to understand how changing crustal input is tied to volcanic output, and ultimately build a much better understanding of what happens to tectonic plates once they get transported into the deep Earth.”
Reference:
William Hutchison et al. Sulphur isotopes of alkaline magmas unlock long-term records of crustal recycling on Earth, Nature Communications (2019). DOI: 10.1038/s41467-019-12218-1
The mineral olivine contains melt inclusions (black dots), just a few micrometers in size. The geochemists isolated these inclusions and investigated the isotopic composition with mass spectrometers. Credit: Münster University – Felix Genske
What is the chemical composition of the Earth’s interior? Because it is impossible to drill more than about ten kilometres deep into the Earth, volcanic rocks formed by melting Earth’s deep interior often provide such information. Geochemists at the Universities of Münster (Germany) and Amsterdam (Netherlands) have investigated the volcanic rocks that build up the Portuguese island group of the Azores. Their goal: gather new information about the compositional evolution of the Earth’s mantle, which is the layer roughly between 30 and 2,900 kilometres deep inside the Earth. Using sophisticated analytical techniques, they discovered that the composition of the mantle below the Azores is different than previously thought—suggesting that large parts of it contain surprisingly few so-called incompatible elements. These are chemical elements which, as a result of the constant melting of the Earth’s mantle, accumulate in the Earth’s crust, which is Earth’s outermost solid layer.
The researchers conclude that, over Earth’s history, a larger amount of Earth’s mantle has melted—and ultimately formed the Earth’s crust—than previously thought. “To sustain the material budget between Earth’s mantle and crust, mass fluxes between the surface and Earth’s interior must have operated at a higher rate,” says Münster University’s Prof. Andreas Stracke, who is heading the study.
As the material below the Azores rises from very deep within Earth’s mantle—and is unexpectedly similar to most of its upper part—the composition of Earth’s entire mantle may differ from current thinking. “Our results have opened up a new perspective,” says Andreas Stracke, “because we will now have to reassess the composition of the largest part of the Earth—after all, Earth’s mantle accounts for over 80 percent of Earth’s volume.” The study has been published in the journal Nature Geoscience.
Background and method
In their study, the geochemists examined the mineral olivine and its melt inclusions, i.e. magma encapsulated during the crystallisation of olivine before the lavas erupted. The researchers isolated these melt inclusions, just a few micrometers in size, dissolved them chemically and separated certain chemical elements. These elements are altered by radioactive decay during their lifetime and ascent from Earth’s interior—travelling over thousands of kilometres for hundreds or even thousands of millions of years.
The researchers analysed the isotopic composition of the melts with highly sensitive mass spectrometers. Such methods allow measurement of the relative abundance of different atoms in an element—so-called isotopes. “Owing to the high efficiency of our measurements, we were able to analyse the isotopic composition of one billionth of a gram of the element,” says co-author Dr. Felix Genske from the University of Münster’s Institute of Mineralogy, who carried out most of the analytical work. In this way, the researchers indirectly obtained information on the composition of the material in the Earth’s mantle: the isotope analyses showed that it contains far fewer rare Earth elements such as samarium and neodymium, but also of chemically similar elements such as thorium and uranium.
“On the basis of similar geochemical data in volcanic rocks from different regions, e.g. Hawaii, other parts of the Earth’s mantle may also contain a higher proportion of material that is strongly depleted in incompatible elements,” says Andreas Stracke. The researchers presume that this global deficit may be compensated by a higher rate of recycling Earth’s incompatible element-rich crust back into Earth’s mantle. With their continuing studies the researchers want to confirm their working hypothesis by investigating samples from other volcanic islands across the globe.
Reference:
Andreas Stracke et al, Ubiquitous ultra-depleted domains in Earth’s mantle, Nature Geoscience (2019). DOI: 10.1038/s41561-019-0446-z
An artist’s interpretation of the asteroid impact that wiped out all non-avian dinosaurs. Credit: NASA/Don Davis.
When the asteroid that wiped out the dinosaurs slammed into the planet, the impact set wildfires, triggered tsunamis and blasted so much sulfur into the atmosphere that it blocked the sun, which caused the global cooling that ultimately doomed the dinos.
That’s the scenario scientists have hypothesized. Now, a new study led by The University of Texas at Austin has confirmed it by finding hard evidence in the hundreds of feet of rocks that filled the impact crater within the first 24 hours after impact.
The evidence includes bits of charcoal, jumbles of rock brought in by the tsunami’s backflow and conspicuously absent sulfur. They are all part of a rock record that offers the most detailed look yet into the aftermath of the catastrophe that ended the Age of Dinosaurs, said Sean Gulick, a research professor at the University of Texas Institute for Geophysics (UTIG) at the Jackson School of Geosciences.
“It’s an expanded record of events that we were able to recover from within ground zero,” said Gulick, who led the study and co-led the 2016 International Ocean Discovery Program scientific drilling mission that retrieved the rocks from the impact site offshore of the Yucatan Peninsula. “It tells us about impact processes from an eyewitness location.”
The research was published in the Proceedings of the National Academy of Sciences on Sept. 9 and builds on earlier work co-led and led by the Jackson School that described how the crater formed and how life quickly recovered at the impact site. An international team of more than two dozen scientists contributed to this study.
Most of the material that filled the crater within hours of impact was produced at the impact site or was swept in by seawater pouring back into the crater from the surrounding Gulf of Mexico. Just one day deposited about 425 feet of material — a rate that’s among the highest ever encountered in the geologic record. This breakneck rate of accumulation means that the rocks record what was happening in the environment within and around the crater in the minutes and hours after impact and give clues about the longer-lasting effects of the impact that wiped out 75% of life on the planet.
Gulick described it as a short-lived inferno at the regional level, followed by a long period of global cooling.
“We fried them and then we froze them,” Gulick said. “Not all the dinosaurs died that day, but many dinosaurs did.”
Researchers estimate the asteroid hit with the equivalent power of 10 billion atomic bombs of the size used in World War II. The blast ignited trees and plants that were thousands of miles away and triggered a massive tsunami that reached as far inland as Illinois. Inside the crater, researchers found charcoal and a chemical biomarker associated with soil fungi within or just above layers of sand that shows signs of being deposited by resurging waters. This suggests that the charred landscape was pulled into the crater with the receding waters of the tsunami.
Jay Melosh, a Purdue University professor and expert on impact cratering, said that finding evidence for wildfire helps scientists know that their understanding of the asteroid impact is on the right track.
“It was a momentous day in the history of life, and this is a very clear documentation of what happened at ground zero,” said Melosh, who was not involved with this study.
However, one of the most important takeaways from the research is what was missing from the core samples. The area surrounding the impact crater is full of sulfur-rich rocks. But there was no sulfur in the core.
That finding supports a theory that the asteroid impact vaporized the sulfur-bearing minerals present at the impact site and released it into the atmosphere, where it wreaked havoc on the Earth’s climate, reflecting sunlight away from the planet and causing global cooling. Researchers estimate that at least 325 billion metric tons would have been released by the impact. To put that in perspective, that’s about four orders of magnitude greater than the sulfur that was spewed during the 1883 eruption of Krakatoa — which cooled the Earth’s climate by an average of 2.2 degrees Fahrenheit for five years.
Although the asteroid impact created mass destruction at the regional level, it was this global climate change that caused a mass extinction, killing off the dinosaurs along with most other life on the planet at the time.
“The real killer has got to be atmospheric,” Gulick said. “The only way you get a global mass extinction like this is an atmospheric effect.”
The research was funded by a number of international and national support organizations, including the National Science Foundation.
Reference:
Sean P. S. Gulick, Timothy J. Bralower, Jens Ormö, Brendon Hall, Kliti Grice, Bettina Schaefer, Shelby Lyons, Katherine H. Freeman, Joanna V. Morgan, Natalia Artemieva, Pim Kaskes, Sietze J. de Graaff, Michael T. Whalen, Gareth S. Collins, Sonia M. Tikoo, Christina Verhagen, Gail L. Christeson, Philippe Claeys, Marco J. L. Coolen, Steven Goderis, Kazuhisa Goto, Richard A. F. Grieve, Naoma McCall, Gordon R. Osinski, Auriol S. P. Rae, Ulrich Riller, Jan Smit, Vivi Vajda, Axel Wittmann, and the Expedition 364 Scientists. The first day of the Cenozoic. PNAS, 2019 DOI: 10.1073/pnas.1909479116
A newly identified species of pterosaur is among the largest ever flying animals, according to a new study from Queen Mary University of London.
Cryodrakon boreas, from the Azhdarchid group of pterosaurs (often incorrectly called ‘pterodactyls’), was a flying reptile with a wingspan of up to 10 metres which lived during the Cretaceous period around 77 million years ago.
Its remains were discovered 30 years ago in Alberta, Canada, but palaeontologists had assumed they belonged to an already known species of pterosaur discovered in Texas, USA, named Quetzalcoatlus.
The study, published in the Journal of Vertebrate Paleontology, reveals it is actually a new species and the first pterosaur to be discovered in Canada.
Dr David Hone, lead author of the study from Queen Mary University of London, said: “This is a cool discovery, we knew this animal was here but now we can show it is different to other azhdarchids and so it gets a name.”
Although the remains — consisting of a skeleton that has part of the wings, legs, neck and a rib — were originally assigned to Quetzalcoatlus, study of this and additional material uncovered over the years shows it is a different species in light of the growing understanding of azhdarchid diversity.
The main skeleton is from a young animal with a wingspan of about 5 metres but one giant neck bone from another specimen suggests an adult animal would have a wingspan of around 10 metres.
This makes Cryodrakon boreas comparable in size to other giant azhdarchids including the Texan Quetzalcoatlus which could reach 10.5 m in wingspan and weighed around 250 kg.
Like other azhdarchids these animals were carnivorous and predominantly predated on small animals which would likely include lizards, mammals and even baby dinosaurs.
Dr Hone added: “It is great that we can identify Cryodrakon as being distinct to Quetzalcoatlus as it means we have a better picture of the diversity and evolution of predatory pterosaurs in North America.”
Unlike most pterosaur groups, azhdarchids are known primarily from terrestrial settings and, despite their likely capacity to cross oceanic distances in flight, they are broadly considered to be animals that were adapted for, and lived in, inland environments.
Despite their large size and a distribution across North and South America, Asia, Africa and Europe, few azhdarchids are known from more than fragmentary remains. This makes Cryodrakon an important animal since it has very well preserved bones and includes multiple individuals of different sizes.
Reference:
David W. E. Hone, Michael B. Habib, François Therrien. Cryodrakon boreas, gen. et sp. nov., a Late Cretaceous Canadian azhdarchid pterosaur. Journal of Vertebrate Paleontology, 2019; e1649681 DOI: 10.1080/02724634.2019.1649681
Jurassic crocodile. Artist’s impression (credit: Julia Beier)
A prehistoric crocodile that lived around 180 million years ago has been identified — almost 250 years after the discovery of it fossil remains.
A fossil skull found in a Bavarian town in the 1770s has been recognised as the now-extinct species Mystriosaurus laurillardi, which lived in tropical waters during the Jurassic Period.
For the past 60 years, it was thought the animal was part of a similar species, known as Steneosaurus bollensis, which existed around the same time, researchers say.
Palaeontologists identified the animal by analysing fossils unearthed in the UK and Germany.
The team, which included scientists from the University of Edinburgh, also revealed that another skull, discovered in Yorkshire in the 1800s, belongs to Mystriosaurus laurillardi.
The marine predator — which was more than four metres in length — had a long snout and pointed teeth, and preyed on fish, the team says. It lived in warm seas alongside other animals including ammonites and large marine reptiles, called ichthyosaurs.
The discovery of fossils in present-day Germany and the UK shows that the species could easily swim between islands, much like modern saltwater crocodiles, researchers say.
The study, led by Naturkunde-Museum Bielefeld in Germany, is published in the journal Acta Palaeontologica Polonica, It was supported by the Palaeontographical Society, Leverhulme Trust and the Natural Sciences and Engineering Research Council of Canada.
Sven Sachs, of the Naturkunde-Museum Bielefeld, who led the study, said: “Mystriosaurus looked like a gharial but it had a shorter snout with its nasal opening facing forwards, whereas in nearly all other fossil and living crocodiles the nasal opening is placed on top of the snout.”
Dr Mark Young, of the University of Edinburgh’s School of GeoSciences, who was involved in the study, said: “Unravelling the complex history and anatomy of fossils like Mystriosaurus is necessary if we are to understand the diversification of crocodiles during the Jurassic. Their rapid increase in biodiversity between 200 and 180 million years ago is still poorly understood.”
Reference:
Sven Sachs, Michela M. Johnson, Mark T. Young, and Pascal Abel. The mystery of Mystriosaurus: Redescribing the poorly known Early Jurassic teleosauroid thalattosuchians Mystriosauruslaurillardi and Steneosaurus brevior. Acta Palaeontol., Pol. 64 (3): 565%u2013579, 2019 DOI: 10.4202/app.00557.2018
A new study by Yale scientists provides a key insight into a milestone event in the early evolution of life on Earth — the origin of the cell nucleus and complex cells called eukaryotes.
While simple prokaryotic bacteria formed within the first billion years of the Earth, the origin of eurkaryotes, the first cells with nuclei, took much longer. Dating back to between 1.7 and 2.7 billion years ago, an ancient prokaryote was first transformed with a compartment, the nucleus, designed to keep their DNA material more protected from the environment (such as harmful UV damage). From this ancient event, relatively simple organisms, such as bacteria were transformed into more sophisticated ones that ultimately gave rise to all modern animals, plants and fungi.
The details of this key event have remained elusive for many years because not a single transitional fossil has been found to date.
Now, in a study led by Dr. Sergey Melnikov, from the Dieter Söll Laboratory in the Department of Molecular Biophysics and Biochemistry at Yale University, has finally found these missing fossils. To do so, they relied not on unearthing clay or rocks but peering deep inside current living cells, known as Archaea — the organisms that are believed to most closely resemble the ancient intermediates between bacteria and the more complex cells that we now know as eukaryotic cells.
These transitional forms are nothing like the traditional fossils we think of, such as dinosaur bones deposited in the ground or insects trapped in amber. Known as ribosomal proteins, these particular transitional forms are about 100-million times smaller than our bodies. Melnikov and his colleagues discovered that ribosomal proteins can be used as living “molecular fossils,” whose ancient origin and structure may hold the key to understanding the origin of the cell nucleus.
“Simple lifeforms, such as bacteria, are analogous to a studio apartment: they have a single interior space which is not subdivided into separate rooms or compartments. By contrast, more complex organisms, such as fungi, animals, and plants, are made up of cells that are separated into multiple compartments,” explained Melnikov. “These microscopic compartments are connected to one another via ‘doors’ and ‘gates.’ To pass through these doors and gates, the molecules that inhabit living cells must carry special ID badges, some of which are called nuclear localization signals, or NLSs.”
Seeking to better understand when NLS-motifs might have emerged in ribosomal proteins, the Yale team assessed their conservation among ribosomal proteins from the three domains of life.
To date, NLS-motifs have been characterized in ten ribosomal proteins from several eukaryotic species. They compared all of the NLS-motifs found in eukaryotic ribosomal proteins (from 482 species) and tried to find a match in bacteria (2,951 species) and Archaea (402 species).
Suprisingly, they found four proteins — uL3, uL15, uL18, and uS12 — to have NLS-type motifs not only in the Eukarya but also in the Archaea. “Contrary to our expectations, we found that NLS-type motifs are conserved across all the archaeal branches, including the most ancient superphylum, called DPANN,” said Melnikov.
But since Archaea don’t have nuclei, the logical question which then arose was, why do they have these IDs? And what was the original biological function of these IDs in non-compartmentalized cells?”
“If you think about an equivalent to our discovery in the macroscopic world, it is similar to discoveries made during the last century of bird-like dinosaurs such as Caudipteryx zoui,” said Melnikov. “These ancient flightless birds have illustrated that it took multiple millions of years for dinosaurs to develop wings. Yet, strikingly, for the first few million years their wings were not good enough to support flight.”
Similarly, the study by Melnikov and colleagues suggests that, even though NLSs may not initially have emerged to allow cellular molecules to pass through microscopic doors and gates between cellular compartments, they could have emerged to fulfill a similar biological function — to help molecules get to their proper biological partners.
As Melnikov explains: “Our analysis shows that in complex cells the very same IDs that allow proteins to pass through the microscopic gates are also used to recognize biological partners of these proteins. In other words, in complex cells, the IDs fulfill two conceptually similar biological functions. In the Archaea, however, these IDs play just one of these functions — these IDs, or NLSs, help proteins to recognize their biological partners and distinguish them from the thousands of other molecules that float in a cell.”
But what led to the evolution of these IDs among cellular proteins in the first place?
As Melnikov explains, “When life first emerged on the face of our planet, the earliest life forms were likely made of a very limited number of molecules. Therefore, it was relatively easy for these molecules to find one specific partner among all the other molecules in a living cell. However, as cells grew in size and complexity, it is possible, even probable, that the old rules of specific interactions between cellular molecules had to be redefined, and this is how the IDs were introduced into the structure of cellular proteins — to help these proteins identify their molecular partners more easily in the complex environment of a complex cell. Coming back to the analogy with bird-like dinosaurs, our study illustrates the remarkable similarity between how evolution happens in the macroscopic world and how evolution happens in the world that Darwin never saw — the microscopic world of invisible molecules that inhabit living cells.”
Reference:
Sergey Melnikov, Hui-Si Kwok, Kasidet Manakongtreecheep, Antonia van den Elzen, Carson C Thoreen, Dieter Söll. Archaeal ribosomal proteins possess nuclear localization signal-type motifs: implications for the origin of the cell nucleus. Molecular Biology and Evolution, 2019; DOI: 10.1093/molbev/msz207
An in-depth analysis of the skull biomechanics of a giant extinct kangaroo indicates that the animal had a capacity for high-performance crushing of foods, suggesting feeding behaviors more similar to a giant panda than modern-day kangaroo.
The new findings, published in PLOS ONE, support the hypothesis that some short-faced kangaroos were capable of persisting on tough, poor-quality vegetation, when more desirable foods were scarce because of droughts or glacial periods.
“The skull of the extinct kangaroo studied here differs from those of today’s kangaroos in many of the ways a giant panda’s skull differs from other bears,” said Rex Mitchell, post-doctoral fellow in the Department of Anthropology at the University of Arkansas. “So, it seems that the strange skull of this kangaroo was, in a functional sense, less like a modern-day kangaroo’s and more like a giant panda’s.”
Mitchell used computed tomography scans to create three-dimensional models of the skull of Simosthenurus occidentalis, a well-represented species of short-faced kangaroo that persisted until about 42,000 years ago. Working with the models, Mitchell performed bite simulations to examine biomechanical performance. The resulting forces at the jaw joints and biting teeth were measured, as well as stress experienced across the skull during biting.
Mitchell compared the findings from the short-faced kangaroo to those obtained from models of the koala, a species alive today with the most similar skull shape. These comparisons demonstrated the importance of the extinct kangaroo’s bony, heavily reinforced skull features in producing and withstanding strong forces during biting, which likely helped the animal crush thick, resistant vegetation such as the older leaves, woody twigs and branches of trees and shrubs. This would be quite different than the feeding habits of modern Australian kangaroos, which tend to feed mostly on grasses, and would instead be more similar to how giant pandas crush bamboo.
“Compared to the kangaroos of today, the extinct, short-faced kangaroos of ice age Australia would be a strange sight to behold,” Mitchell said.
They included the largest kangaroo species ever discovered, with some species estimated to weigh more than 400 pounds. The bodies of these kangaroos were much more robust than those of today — which top out at about 150 pounds — with long muscular arms and large heads shaped like a koala’s. Their short face offered increased mechanical efficiency during biting, a feature usually found in species that can bite harder into more resistant foods. Some species of these extinct kangaroos had massive skulls, with enormous cheek bones and wide foreheads.
“All this bone would have taken a lot of energy to produce and maintain, so it makes sense that such robust skulls wouldn’t have evolved unless they really needed to bite hard into at least some more resistant foods that were important in their diets,” Mitchell said.
The short face, large teeth, and broad attachment sites for biting muscles found in the skulls of the short-faced kangaroo and the giant panda are an example of convergent evolution, Mitchell said, meaning these features probably evolved in both animals for the purpose of performing similar feeding tasks.
Mitchell is also affiliated with the University of New England in Armidale, Australia, where he performed the analyses during his doctoral studies.
Reference:
D. Rex Mitchell. The anatomy of a crushing bite: The specialised cranial mechanics of a giant extinct kangaroo. PLOS ONE, 2019; 14 (9): e0221287 DOI: 10.1371/journal.pone.0221287
Prof. Michael Coates holds a 3-D printed model of the Tristychius skull and jaws. Photo courtesy of Matt Wood
Researchers from the University of Chicago have used tools developed to explore 3D movements and mechanics of modern-day fish jaws to analyze a fossil fish for the first time. Combined with CT imaging technology able to capture images of the fossil while it is still encased in rock, the results reveal that the 335-million-year-old shark had sophisticated jaws capable of the kind of suction feeding common to bony fishes like bass, perch, carp and also modern-day nurse sharks.
Remarkably, these ancient shark jaws are some 50 million years older than the earliest evidence of similar jaws adapted for suction feeding in bony fishes. This shows both the evolutionary versatility of sharks, and how sharks responded quickly to new ecological opportunities in the aftermath of one of the five big extinctions in Earth’s history.
“Among today’s aquatic vertebrates, suction feeding is widespread, and is often cited as a key factor contributing to the spectacular evolutionary success of ray-finned fishes,” said Michael Coates, PhD, professor of organismal biology and anatomy at the University of Chicago and senior author of the new study. “But here we show that high-performance aquatic suction feeding first appeared in one of the earliest known sharks.”
A complete construction kit to rebuild a shark
The study, published this week in Science Advances, describes the fossil of Tristychius arcuatus, a 2-foot long shark similar to a dogfish. It was first discovered by Swiss biologist Louis Agassiz in 1837, and later described in detail by John Dick, a former classmate of Coates’, in 1978. Tristychius, and other Devonian period sharks like it, are found in ironstone rock nodules along the shores of the Firth of Forth near Edinburgh, Scotland.
Shark fossils are rare because their cartilage skeleton usually rots away before there’s any chance of fossilization. For decades, researchers studying ancient sharks have been limited to isolated teeth and fin spines. Even if they do find a more complete skeleton, it’s usually flattened, or, if it’s encased in one of these stones, it crumbles when they try to remove it.
Coates and his lab have been leading the field in applying modern imaging technology and software to study these challenging fossils. CT scanning allows them to create 3D images of any fossilized cartilage and the impressions it left while still encased in the stone. Then, using sophisticated modeling software originally developed to study structure and function in modern-day fish, they can recreate what the complete skeleton looked like, how the pieces fit together and moved, and what that meant for how these sharks lived.
“These new CT methods are releasing a motherlode of previously inaccessible data,” Coates said.
His team started reexamining some of the same fossils Dick studied, as well as specimens left untouched in earlier research. “Some of this is superbly preserved,” Coates said. “We realized that when we got all the parts out [virtually], we had the complete construction kit to rebuild our shark in 3D.”
Beating underwater physics
That virtual construction kit also allowed them to create 3D plastic printouts of the cartilages that build a shark’s skull. These, in turn, allowed Coates and his team to model movements and connections, both physically and virtually, to see how the skull worked.
Fish that use suction feeding essentially suck water in through their mouths to catch elusive prey, such as worms, crustaceans and other invertebrates from the ocean floor. To do so, they have to draw water in when they open their mouth, but not force it back out when they close it.
Suction feeders overcome these challenging physics by funneling the water back out through their gills. The amount of suction they create can be enhanced by flexible arches and joints that expand the cheeks and the volume inside the mouth to draw the water through (imagine the feeling when you hold your hands together underwater and slowly pull your palms apart).
Today’s fish have perfected this process, but Tristychius had a similar feeding apparatus that could expand as it opened and closed its mouth to control the flow of water (and food). Crucially, this included a set of cartilages around the mouth that limited the size of the opening to control the amount of suction. The circular mouth was pushed forward at the end of its muzzle like a modern-day carpet shark or nurse shark, not a gaping, toothy maw like a great white.
While other sharks at the time did have the more typical snapping jaws, the combination of expanding cheeks and a carefully controlled mouth aperture provided Tristychiuswith access to previously untapped food resources, such as prey taking refuge in shallow burrows or otherwise difficult-to-capture schools of shrimp or juvenile fish, around 50 million years before bony fish caught on to the same technique.
“The combination of both physical and computational models has allowed us to explore the biomechanics in a Paleozoic shark in a way that’s never been done before,” Coates said. “These particular sharks were doing something sophisticated and new. Here we have the earliest evidence of this key innovation that’s been so important for multiple groups of fishes and has evolved repeatedly.”
Additional authors for the study include Kristen Tietjenfrom the University of Chicago, Aaron M. Olsenfrom Brown University, and John A. Finarelli from University College Dublin, Ireland.
Reference:
Michael I. Coates, Kristen Tietjen, Aaron M. Olsen and John A. Finarelli. High-performance suction feeding in an early elasmobranch. Science Advances, 2019 DOI: 10.1126/sciadv.aax2742
Two palaeontologists working on the world-renowned Burgess Shale have revealed a new species, called Mollisonia plenovenatrix, which is presented as the oldest chelicerate. This discovery places the origin of this vast group of animals — of over 115,000 species, including horseshoe crabs, scorpions and spiders — to a time more than 500 million years ago. The findings are published in the journal Nature on September 11, 2019.
Mollisonia plenovenatrix would have been a fierce predator — for its size. As big as a thumb, the creature boasted a pair of large egg-shaped eyes and a “multi-tool head” with long walking legs, as well as numerous pairs of limbs that could all-together sense, grasp, crush and chew. But, most importantly, the new species also had a pair of tiny “pincers” in front of its mouth, called chelicerae. These typical appendages give the name to the group of scorpions and spiders, the chelicerates, which use them to kill, hold, and sometimes cut, their prey.
“Before this discovery, we couldn’t pinpoint the chelicerae in other Cambrian fossils, although some of them clearly have chelicerate-like characteristics,” says lead author Cédric Aria, a member of the Royal Ontario Museum’s Burgess Shale expeditions since 2012, and is presently a post-doctoral fellow at the Nanjing Institute of Geology and Palaeontology (China). “This key feature, this coat of arms of the chelicerates, was still missing.”
Other features of this fossil, including back limbs likened to gills, further suggest that Mollisonia was not some “primitive” version of a chelicerate, but that it was in fact already close morphologically to modern species.
“Chelicerates have what we call either book gills or book lungs,” explains Aria. “They are respiratory organs are made of many collated thin sheets, like a book. This greatly increases surface area and therefore gas exchange efficiency. Mollisonia had appendages made up with the equivalent of only three of these sheets, which probably evolved from simpler limbs.”
The authors believe that Mollisonia preferentially hunted close to the sea floor, thanks to its well-developed walking legs, a type of ecology called benthic predation. Because Mollisonia is so modern-looking, chelicerates seem therefore to have prospered quickly, filling in an ecological niche that was otherwise left poorly attended to by other arthropods at that time. The authors conclude that the origin of the chelicerates must lie even deeper within the Cambrian, when the heart of the “explosion” really took place.
“Evidence is converging towards picturing the Cambrian explosion as even swifter than what we thought,” says Aria. “Finding a fossil site like the Burgess Shale at the very beginning of the Cambrian would be like looking into the eye of the cyclone.”
The importance of the Burgess Shale and similar deposits, such as the Chengjiang biota in China, lies in their exceptional preservation of the earliest marine animal communities at a time of uniquely rapid diversification of body forms called the “Cambrian explosion.” Fossil animals from these sites are notable for preserving an extensive array of morphological features, such as limbs and eyes, but also guts and, much more rarely, nervous system tissues.
Mollisonia was first described more than a century ago by the discoverer of the Burgess Shale, Charles Doolittle Walcott. However, so far, only rare exoskeletons of this animal were known. “It is the first time that evidence of the limbs and other soft-tissues of this type of animal are described, which were key to revealing its affinity,” says co-author Jean-Bernard Caron, Richard M. Ivey Curator of Invertebrate Palaeontology at the Royal Ontario Museum (Canada). The exceptionally well-preserved fossils come from a new Burgess Shale sites near Marble Canyon, in Kootenay National Park, British Columbia.
“Marble Canyon is the biggest spotlight of my career so far. This area keeps giving us wonderful treasures year after year,” says Caron, who has been leading the Royal Ontario Museum’s Burgess Shale expeditions for the past 10 years. “I would not have imagined that we could, in a way, rediscover the Burgess Shale like this, a hundred years later, with all the new species we are finding.”
The specimens of Mollisonia plenovenatrix described in this new research are better preserved than the ones found at the original Walcott quarry that is located about 40 kilometers northwest of the Marble Canyon quarry. Many other fossils found at Marble Canyon and surrounding areas have already played a critical role in our understanding of the early evolution of many animal groups. These notably include the vertebrates, our own lineage, thanks to numerous and exceptionally well-preserved specimens of the primitive fish Metaspriggina walcotti. Many new species await to be described; the latest one, a “flying saucer-like” new predatory arthropod with huge rake-like claws called Cambroraster falcatus, was just recently published on July 31, 2019.
The Burgess Shale fossil sites are located within Yoho and Kootenay national parks and are managed by Parks Canada. Parks Canada is proud to work with leading scientific researchers to expand knowledge and understanding of this key period of earth history and to share these sites with the world through award-winning guided hikes. The Burgess Shale was designated a UNESCO World Heritage Site in 1980 due to its outstanding universal value and is now part of the larger Canadian Rocky Mountain Parks World Heritage Site.
Mollisonia will be among the many exceptional fossils from the Burgess Shale planned to be on display in the ROM’s future new gallery, The Willner Madge Gallery, Dawn of Life, scheduled to open in 2021.
Reference:
Cédric Aria, Jean-Bernard Caron. A middle Cambrian arthropod with chelicerae and proto-book gills. Nature, 2019; DOI: 10.1038/s41586-019-1525-4
