(Press-News.org) Researchers believe they have closed the case of what killed the dinosaurs, definitively linking their extinction with an asteroid that slammed into Earth 66 million years ago by finding a key piece of evidence: asteroid dust inside the impact crater.
Death by asteroid rather than by a series of volcanic eruptions or some other global calamity has been the leading hypothesis since the 1980s, when scientists found asteroid dust in the geologic layer that marks the extinction of the dinosaurs. This discovery painted an apocalyptic picture of dust from the vaporized asteroid and rocks from impact circling the planet, blocking out the sun and bringing about mass death through a dark, sustained global winter - all before drifting back to Earth to form the layer enriched in asteroid material that's visible today.
In the 1990s, the connection was strengthened with the discovery of a 125-mile-wide Chicxulub impact crater beneath the Gulf of Mexico that is the same age as the rock layer. The new study seals the deal, researchers said, by finding asteroid dust with a matching chemical fingerprint within that crater at the precise geological location that marks the time of the extinction.
"The circle is now finally complete," said Steven Goderis, a geochemistry professor at the Vrije Universiteit Brussel, who led the study published in Science Advances on Feb. 24.
The study is the latest to come from a 2016 International Ocean Discovery Program mission co-led by The University of Texas at Austin that collected nearly 3,000 feet of rock core from the crater buried under the seafloor. Research from this mission has helped fill in gaps about the impact, the aftermath and the recovery of life.
The telltale sign of asteroid dust is the element iridium - which is rare in the Earth's crust, but present at elevated levels in certain types of asteroids. An iridium spike in the geologic layer found all over the world is how the asteroid hypothesis was born. In the new study, researchers found a similar spike in a section of rock pulled from the crater. In the crater, the sediment layer deposited in the days to years after the strike is so thick that scientists were able to precisely date the dust to a mere two decades after impact.
"We are now at the level of coincidence that geologically doesn't happen without causation," said co-author Sean Gulick, a research professor at the UT Jackson School of Geosciences who co-led the 2016 expedition with Joanna Morgan of Imperial College London. "It puts to bed any doubts that the iridium anomaly [in the geologic layer] is not related to the Chicxulub crater."
The dust is all that remains of the 7-mile-wide asteroid that slammed into the planet millions of years ago, triggering the extinction of 75% of life on Earth, including all nonavian dinosaurs.
Researchers estimate that the dust kicked up by the impact circulated in the atmosphere for no more than a couple of decades - which, Gulick points out, helps time how long extinction took.
"If you're actually going to put a clock on extinction 66 million years ago, you could easily make an argument that it all happened within a couple of decades, which is basically how long it takes for everything to starve to death," he said.
The highest concentrations of iridium were found within a 5-centimeter section of the rock core retrieved from the top of the crater's peak ring - a high-elevation point in the crater that formed when rocks rebounded then collapsed from the force of impact.
The iridium analysis was carried out by labs in Austria, Belgium, Japan and the United States.
"We combined the results from four independent laboratories around the world to make sure we got this right," said Goderis.
In addition to iridium, the crater section showed elevated levels of other elements associated with asteroid material. The concentration and composition of these "asteroid elements" resembled measurements taken from the geologic layer at 52 sites around the world.
The core section and geologic layer also have earthbound elements in common, including sulfurous compounds. A 2019 study found that sulfur-bearing rocks are missing from much of the rest of the core despite being present in large volumes in the surrounding limestone. This indicates that the impact blew the original sulfur into the atmosphere, where it may have made a bad situation worse by exacerbating global cooling and seeding acid rain.
Gulick and colleagues at the University of Texas Institute for Geophysics and Bureau of Economic Geology - both units of the UT Jackson School - plan to return to the crater this summer to begin surveying sites at its center, where they hope to plan a future drilling effort to recover more asteroid material.
COLUMBUS, Ohio - Politicization of the COVID-19 pandemic had a powerful influence over adherence to social distancing guidelines in the United States and why people did, or did not, comply during the lockdown days, a new study has found.
The analysis boiled down to whom study participants trusted most: scientists or President Donald Trump.
"People who expressed a great deal of faith in President Trump, who thought he was doing an effective job of guiding us through the pandemic, were less likely to socially distance," said Russell Fazio, senior author of the study and a professor ...
Ultra-fast, cheap LAMP-based COVID tests could be performed by non-experts at work and in public spaces, giving results in under an hour
Article Title: "Ultra-rapid detection of SARS-CoV-2 in public workspace environments"
Funding: This project was made possible through the support of a grant from Dynamic Combinatorial Chemistry, LLC, The funder provided support in the form of salaries and supplies for authors OY, ZY, JM, and BO, but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific ...
Improving road safety in cities could result in a lower rate of violent crime, according to research from UCL.
Experts analysing crime and car accident data in Mexico City found a surprisingly high level of synchronicity between the two on a weekly cycle, suggesting that applying more resources to prevent road accidents would improve crime rates by enabling more efficient policing.
For the paper, published today in Cities as Complex Systems special issue in PLOS ONE, experts plotted the time and locations of nearly one million car accidents and 200,000 ...
CLEVELAND, Ohio - Researchers at University Hospitals Rainbow Babies & Children's Hospital (UH Rainbow) published new findings today that wearing a face mask - either a cloth mask or a surgical mask - did not impair the ability of subjects to get air in and out of their bodies.
The study measured heart rate, transcutaneous carbon dioxide tension, and oxygen levels in 50 adult volunteers at the conclusion of six 10-minute phases: Sitting quietly and then walking briskly without a mask; sitting quietly and then walking briskly while wearing a cloth mask; and sitting quietly and then walking ...
WATERTOWN, Mass. - Gene therapy has traditionally been conceptualized as a one-time, curative treatment option; however, research shows that there may be a need for subsequent doses years after initial treatment. While adeno-associated viral (AAV) vectors are a core part of this powerful therapeutic approach, they present two key challenges in gene therapy.
The first challenge is their immunogenicity. In gene therapy, the formation of neutralizing antibodies (Nabs) in response to AAV vector administration precludes retreatment of a patient due to the potentially dangerous immune response that would occur after a second or third administration of the therapy.
The second obstacle relates to their durability. AAV vectors ...
A new study published Feb. 24 in the journal Royal Society Open Science documents the earliest-known fossil evidence of primates.
A team of 10 researchers from across the U.S. analyzed several fossils of Purgatorius, the oldest genus in a group of the earliest-known primates called plesiadapiforms. These ancient mammals were small-bodied and ate specialized diets of insects and fruits that varied by species. These newly described specimens are central to understanding primate ancestry and paint a picture of how life on land recovered after the Cretaceous-Paleogene extinction event 66 million years ago that wiped out all dinosaurs -- except for birds -- and led to the rise of mammals.
Gregory Wilson Mantilla, a University of Washington professor of biology and curator of vertebrate ...
A research team from Skoltech and FBK (Italy) presented a methodology to derive 4D building models using historical maps and machine learning. The implemented method relies on the geometric, neighbourhood, and categorical attributes to predict building heights. The method is useful for understanding urban phenomena and changes contributing to defining our cities' actual shapes. The results were published in the MDPI Applied Sciences journal.
Historical maps are the most powerful source used to analyze changes in urban development. Nevertheless, maps represent the 3D world ...
Freshwater is accumulating in the Arctic Ocean. The Beaufort Sea, which is the largest Arctic Ocean freshwater reservoir, has increased its freshwater content by 40% over the past two decades. How and where this water will flow into the Atlantic Ocean is important for local and global ocean conditions.
A study from the University of Washington, Los Alamos National Laboratory and the National Oceanic and Atmospheric Administration shows that this freshwater travels through the Canadian Archipelago to reach the Labrador Sea, rather than through the wider marine passageways that connect to seas in Northern Europe. The open-access study was published Feb. 23 ...
Emerging smart mobile health (or mHealth) technologies are changing the way patients track information related to diagnosed conditions. A new study examined the health and economic impacts of mHealth technologies on the outcomes of diabetes patients in Asia. The study concluded that compared to patients who did not use mHealth applications, patients who used the apps had better health outcomes and were able to regulate their health behavior more effectively. They also had fewer hospital visits and lower medical costs.
The study was conducted by researchers at Carnegie Mellon University (CMU) and New York University ...
New Orleans, LA -- A new study of how the 2020 major hurricanes and the COVID-19 pandemic affected each other as well as disaster response found that although prior experience enabled community-based organizations to respond to the pandemic, the pandemic is also creating new challenges to preparing for and responding to natural disasters. The research is published in the International Journal of Environmental Research and Public Health, available here.
"Two major crises hit Louisiana and coastal communities in the Southeastern United States in 2020 - a significant increase in the frequency and severity of hurricanes, and the COVID-19 pandemic," says Benjamin Springgate, MD, MPH, Chief of Community & Population Medicine at ...